BB unit 2 quizzes and ICAs

Autoimmune hemolytic anemia (AIHA) is classified into which of the following categories based on antibody type?

-Type 1, Type 2, and Type 3 AIHA, based on antibody titer alone

- AIHA is classified exclusively by the patient's ABO group

- Only warm AIHA and cold AIHA, with no other subtypes

- Cold AIHA (IgM), warm AIHA (IgG), mixed-type (IgM + IgG), and PCH (IgG biphasic hemolysin)

Cold AIHA (IgM), warm AIHA (IgG), mixed-type (IgM + IgG), and PCH (IgG biphasic hemolysin)

A neutralization study for suspected anti-Leb is performed. The control (plasma + saline) shows 0 reactivity, and the neutralized tube (plasma + Lewis substance) also shows 0 reactivity. What is the correct interpretation?

 

-The antibody must be a warm autoantibody, since neutralization failed

-The antibody has been definitively neutralized and confirmed as anti-Leb

-The test is invalid and no interpretation is possible under any circumstances

-The antibody was likely already weak/diluted; true neutralization cannot be confirmed, and antibody specificity remains undetermined

The antibody was likely already weak/diluted; true neutralization cannot be confirmed, and antibody specificity remains undetermined

Secondary, acute Cold Agglutinin Syndrome (CAS) is most classically associated with which of the following?

- Mycoplasma pneumoniae infection or infectious mononucleosis

- Waldenstrom macroglobulinemia

-A hereditary condition present since birth

-Chronic lymphocytic leukemia (CLL) in an elderly patient

Mycoplasma pneumoniae infection or infectious mononucleosis

Paroxysmal Cold Hemoglobinuria (PCH) is caused by which type of antibody?

-A complement-independent IgG antibody with anti-Rh specificity

-A biphasic hemolysin (the Donath-Landsteiner antibody), an IgG with anti-P specificity

-A monoclonal IgM antibody with anti-I specificity

-A polyclonal IgA antibody with anti-Lewis specificity

A biphasic hemolysin (the Donath-Landsteiner antibody), an IgG with anti-P specificity

Anti-i is a relatively uncommon autoantibody in adults primarily because:

- Anti-i is destroyed immediately by complement upon formation

-The i antigen is only found in blood group AB individuals

-The i antigen does not exist in humans

-Adult red cells are typically i-negative (predominantly I-antigen), making anti-i reactivity less likely to be clinically encountered

Adult red cells are typically i-negative (predominantly I-antigen), making anti-i reactivity less likely to be clinically encountered

Secondary, chronic Cold Agglutinin Syndrome (CAS) is most classically associated with which patient population?

-Young adults with infectious mononucleosis only

- Healthy adults with no underlying disease

- Elderly patients with lymphoma, chronic lymphocytic leukemia (CLL), or Waldenstrom macroglobulinemia

-Children following a recent viral illness

Elderly patients with lymphoma, chronic lymphocytic leukemia (CLL), or Waldenstrom macroglobulinemia

A cold panel performed on a group A patient's plasma shows 1+ reactivity with both cord cells, 1+ reactivity with A1 cells, and 2+ reactivity with A2 cells, all at 4 C. What antibody specificity is most consistent with this pattern, and why does A2 react more strongly than A1?

-Anti-I; A2 cells always react more strongly than A1 cells with any cold antibody

- Anti-HI; A2 cells express more H antigen than A1 cells, so a cold antibody reacting with both the H and I antigens shows stronger reactivity with A2

-Anti-Pr; Pr antigen is destroyed on A1 cells but preserved on A2 cells

-Anti-P1; P1 antigen is expressed more strongly on A2 cells than A1 cells

Anti-HI; A2 cells express more H antigen than A1 cells, so a cold antibody reacting with both the H and I antigens shows stronger reactivity with A2

. In PCH, full complement activation and hemolysis occur under which condition?

-Only in the presence of a concurrent bacterial infection

-Immediately upon antibody binding in the cold extremities

-Only after the antibody-coated red cells are warmed back to 37 C

-PCH never involves complement activation

Only after the antibody-coated red cells are warmed back to 37 C

In Cold Agglutinin Syndrome (CAS), why does the DAT typically show a positive reaction for complement (C3) rather than for IgM directly?

-IgM antibodies can never be detected by a DAT under any circumstances

-The IgM autoantibody dissociates from the red cell as it warms back to core body temperature, leaving behind complement (C3b, cleaved to C3d) that remains attached

-Complement is the only immunoglobulin class capable of binding red cells

-The IgM antibody is destroyed by the complement cascade before it can bind

The IgM autoantibody dissociates from the red cell as it warms back to core body temperature, leaving behind complement (C3b, cleaved to C3d) that remains attached

A cold autoantibody screen/panel is most useful for which of the following purposes?

-Directly measuring the patient's hemoglobin concentration

-Confirming the presence of a cold autoantibody and helping identify its specificity (if applicable) before pursuing further identification or avoidance techniques

-Replacing the need for an antibody screen entirely

-Determining the patient's Rh type exclusively

Confirming the presence of a cold autoantibody and helping identify its specificity (if applicable) before pursuing further identification or avoidance techniques

A patient's laboratory results show a positive DAT for complement (C3) only, hemoglobinuria, and a history of a recent viral illness in a pediatric patient. The Donath-Landsteiner test is positive. Which condition is most consistent with these findings, and how would this differ from Cold Agglutinin Syndrome (CAS) in terms of antibody class?

-Paroxysmal Nocturnal Hemoglobinuria (PNH); no antibody is involved in this condition

-Paroxysmal Cold Hemoglobinuria (PCH); the causative antibody is IgG (a biphasic hemolysin), whereas CAS is caused by an IgM autoantibody

-Cold Agglutinin Syndrome (CAS); the causative antibody is IgG in both PCH and CAS

-Warm autoimmune hemolytic anemia; the causative antibody is IgM

Paroxysmal Cold Hemoglobinuria (PCH); the causative antibody is IgG (a biphasic hemolysin), whereas CAS is caused by an IgM autoantibody

Anti-Pr, though rare, is notable for which of the following characteristics?

-It equally reactive with all cells, non-reactive with when cells are treated with enzymes, and is associated with rubella infection

-It reacts only with cord blood cells and never with adult red cells

-It is the most commonly encountered cold autoantibody in the general population

-It is exclusively found in individuals with the Bombay phenotype

It equally reactive with all cells, non-reactive with when cells are treated with enzymes, and is associated with rubella infection

A reaction persists through the AHG phase, and the MLS wants to determine whether this is due to a clinically insignificant cold antibody with an unusually wide thermal range, or a true, clinically significant IgG antibody. Which technique would best resolve this?

-Adding more reagent red cells to the same tube

-Increasing the incubation temperature to 45 C

-Performing a saline replacement technique

-Treating the plasma with 0.01M DTT and comparing the treated result to a saline dilution control

Treating the plasma with 0.01M DTT and comparing the treated result to a saline dilution control

Which of the following cold alloantibody specificities is known to demonstrate dosage, showing variable reaction strength depending on antigen zygosity?

-Anti-Lea

-Anti-M and anti-N

-Anti-Leb

-Anti-P1 exclusively, with no variability from M or N

Anti-M and anti-N

Rabbit erythrocyte stroma (RESt) is useful for adsorbing cold autoantibodies, but has which important limitation?

-It permanently alters the patient's Rh type

-It is only effective against IgG antibodies, not IgM

-It cannot be used for reverse grouping or crossmatch, since RESt carries B-like antigens and may also adsorb anti-Vel and other clinically significant IgM antibodies

-It can only be used on patients who have never been transfused

It cannot be used for reverse grouping or crossmatch, since RESt carries B-like antigens and may also adsorb anti-Vel and other clinically significant IgM antibodies

What is the primary purpose of a dilution control (plasma plus saline) when performing a neutralization study?

-To directly measure the exact concentration of the antibody present

-To serve as the positive control for the entire test system

-To convert the antibody from IgM to IgG for further testing

-To prove that a negative neutralization result is due to true antibody neutralization and not simply dilution of a weak antibody

To prove that a negative neutralization result is due to true antibody neutralization and not simply dilution of a weak antibody

Which laboratory finding would be most consistent with a diagnosis of Cold Agglutinin Syndrome (CAS)?

-A DAT positive for complement (C3), along with an IgM autoantibody titer that may exceed 1000 when tested at 4 C

-A markedly decreased reticulocyte count

-A DAT positive for IgG only, with a normal haptoglobin level

-A completely negative DAT with a normal LDH

A DAT positive for complement (C3), along with an IgM autoantibody titer that may exceed 1000 when tested at 4 C

Cold alloantibodies are most typically characterized by which immunoglobulin class and reactivity pattern?

-IgM, reactive at immediate spin and sometimes at 37 C

-IgA, reactive exclusively at 4 C

-IgG, reactive only at the AHG phase

-IgM, reactive only at the AHG phase

IgM, reactive at immediate spin and sometimes at 37 C

In a Lewis neutralization study, the control (plasma + saline) shows 1+ reactivity, and the neutralized tube (plasma + Lewis substance) also shows 1+ reactivity with no reduction. What is the correct interpretation?

-The Lewis antibody was not neutralized, and dilution alone does not explain the persistent reactivity

-The patient has a warm autoantibody instead of a Lewis antibody

-The Lewis antibody has been successfully neutralized

-The specimen must be recollected due to a technical error

The Lewis antibody was not neutralized, and dilution alone does not explain the persistent reactivity

Which substance is classically used to inhibit/neutralize anti-I reactivity in a neutralization study?

-Guinea-pig urine

-Human milk

-Hydatid cyst fluid

-Pooled human urine

Human milk

Cold autoantibodies typically produce a positive DAT due to which mechanism?

-Cold autoantibodies never produce a positive DAT

-Direct IgM coating that persists on the red cell at 37 C

-IgG coating of the red cell membrane

-Complement (C3) deposition on the red cell surface after the IgM autoantibody has dissociated

Complement (C3) deposition on the red cell surface after the IgM autoantibody has dissociated

Which of the following corrective actions can help avoid detecting a clinically insignificant cold alloantibody during routine antibody screening?

-Extending the incubation time at 4 C

-Omitting the immediate-spin and 37 C phase readings, reading only the AHG phase

-Adding additional enhancement media such as PEG

Testing exclusively with enzyme-treated cells

Omitting the immediate-spin and 37 C phase readings, reading only the AHG phase

Autoantibodies are generally distinguished from alloantibodies by which serologic characteristic?

-Autoantibodies are always IgG, while alloantibodies are always IgM

-Autoantibodies can only be detected using enzyme-treated cells

-Autoantibodies never cause a positive DAT

-Autoantibodies react with the patient's own (autologous) red cells in addition to donor and reagent cells

Autoantibodies react with the patient's own (autologous) red cells in addition to donor and reagent cells

Anti-P1 reactivity can be neutralized using which of the following substances?

-Saliva from any secretor

-Human milk

-Pooled human plasma

-Hydatid cyst fluid or pigeon egg white

Hydatid cyst fluid or pigeon egg white

Autoadsorption is an appropriate technique for removing a cold autoantibody under which condition?

-The patient has been transfused within the past week

-The patient is a universal donor with group O blood

-The patient's antibody screen is negative

-The patient has not been transfused within the past 3 months

The patient has not been transfused within the past 3 months

A cold panel is performed on a group O patient's plasma at 4 C, showing 3+ reactivity with both screening cells and the autocontrol, and 0 reactivity with both cord cells. Why is it unnecessary to also test this patient's plasma against A1, A2, and B reagent cells?

-A1, A2, and B cells cannot be tested at 4 C under any circumstances

-As a group O individual, the patient's plasma should already contain naturally occurring anti-A and anti-B, so testing these cells would not add useful information for confirming the cold autoantibody

-Group O patients never demonstrate reactivity with cord blood cells

-Group O patients are physiologically incapable of producing any cold autoantibody

As a group O individual, the patient's plasma should already contain naturally occurring anti-A and anti-B, so testing these cells would not add useful information for confirming the cold autoantibody

Secondary, chronic Cold Agglutinin Syndrome (CAS) is most classically associated with which patient population?

-Elderly patients with lymphoma, chronic lymphocytic leukemia (CLL), or Waldenstrom macroglobulinemia

-Young adults with infectious mononucleosis only

-Children following a recent viral illness

-Healthy adults with no underlying disease

Elderly patients with lymphoma, chronic lymphocytic leukemia (CLL), or Waldenstrom macroglobulinemia

The Donath-Landsteiner test is performed by which procedure?

-Performing a standard antibody screen at room temperature only-

-Incubating patient serum with red blood cells at 37 C only, with no cold phase

-Incubating patient serum with red blood cells at 4 C, then warming to 37 C, and observing for hemolysis after warming

-Testing the patient's saliva for the presence of H substance

Incubating patient serum with red blood cells at 4 C, then warming to 37 C, and observing for hemolysis after warming

In a Lewis neutralization study, the control (plasma + saline) shows 1+ reactivity, and the neutralized tube (plasma + Lewis substance) also shows 1+ reactivity with no reduction. What is the correct interpretation?

-The Lewis antibody has been successfully neutralized

-The patient has a warm autoantibody instead of a Lewis antibody

-The Lewis antibody was not neutralized, and dilution alone does not explain the persistent reactivity

-The specimen must be recollected due to a technical error

The Lewis antibody was not neutralized, and dilution alone does not explain the persistent reactivity

A neutralization study for suspected anti-Leb is performed. The control (plasma + saline) shows 0 reactivity, and the neutralized tube (plasma + Lewis substance) also shows 0 reactivity. What is the correct interpretation?

-The antibody has been definitively neutralized and confirmed as anti-Leb

-The test is invalid and no interpretation is possible under any circumstances

-The antibody must be a warm autoantibody, since neutralization failed

-The antibody was likely already weak/diluted; true neutralization cannot be confirmed, and antibody specificity remains undetermined

The antibody was likely already weak/diluted; true neutralization cannot be confirmed, and antibody specificity remains undetermined

Anti-H (IgM) reactivity can be neutralized/inhibited using saliva from which type of individual?

-A secretor whose saliva contains H substance

- Only individuals with the Bombay phenotype

-Any individual regardless of secretor status

-A non-secretor of any blood group

A secretor whose saliva contains H substance

A patient with a panreactive eluate types as e-antigen positive on their own red cells. Why does this finding argue against a true alloantibody specificity of anti-e?

- Because anti-e can only be made by an e-negative individual reacting to foreign e-positive cells; a patient who is e-positive would not form a true allo-anti-e against their own antigen

-Because e-antigen typing is never reliable on autoantibody-coated cells

-Because anti-e antibodies are always IgM and would not be detected by an eluate

-Because e-positive patients cannot develop warm autoimmune hemolytic anemia

Because anti-e can only be made by an e-negative individual reacting to foreign e-positive cells; a patient who is e-positive would not form a true allo-anti-e against their own antigen

What is the purpose of testing the last wash supernatant before performing an elution?

-To confirm the patient's ABO type

-To serve as a quality control step, confirming that residual free antibody has been adequately removed before the eluate is prepared

-To determine which elution technique should be used

-To measure the patient's hemoglobin level

To serve as a quality control step, confirming that residual free antibody has been adequately removed before the eluate is prepared

A patient's DAT shows anti-C3d reactivity only, with a negative anti-IgG. Why is performing an elution NOT indicated in this case?

-Elution techniques cannot recover complement-bound antibody

-There is no IgG bound to the red cell membrane to elute, since only complement is present

-Elutions are only valid when the DAT is negative

-Elution is contraindicated whenever hemolysis is suspected

There is no IgG bound to the red cell membrane to elute, since only complement is present

A patient recently received IVIG (intravenous immunoglobulin) therapy. How can this affect DAT and eluate testing, potentially mimicking warm autoimmune hemolytic anemia?

-IVIG has no effect on DAT or eluate results

-IVIG can cause a false-positive DAT and a panreactive eluate due to passively transferred antibody coating the red cells

-IVIG always causes a negative DAT regardless of the patient's underlying condition

-IVIG destroys red cell antigens, preventing any antibody detection

IVIG can cause a false-positive DAT and a panreactive eluate due to passively transferred antibody coating the red cells

What is the key difference between an autocontrol and a DAT?

-They are the same test performed on different equipment

-The autocontrol only detects complement, while the DAT only detects IgG

-The autocontrol tests patient cells against patient serum/plasma, while the DAT tests patient cells directly against AHG reagent to detect in vivo sensitization

-The autocontrol is performed only on donor units, while the DAT is performed only on patient samples

The autocontrol tests patient cells against patient serum/plasma, while the DAT tests patient cells directly against AHG reagent to detect in vivo sensitization

Which drug-induced mechanism results in a positive DAT without a true antibody-antigen immune reaction, and instead involves the drug nonspecifically altering the red cell membrane so that plasma proteins adsorb onto it?

-Drug adsorption (hapten) mechanism

-Immune complex mechanism

-Autoantibody induction mechanism

-Membrane modification (nonimmunologic protein adsorption, NIPA)

Membrane modification (nonimmunologic protein adsorption, NIPA)

Which drug-induced mechanism is characterized by antibody-drug immune complexes attaching loosely to the red cell membrane and often fixing complement, typically detected by a positive anti-C3d DAT?

-Drug adsorption (hapten) mechanism

-Immune complex mechanism

-Autoantibody induction mechanism

-Membrane modification (nonimmunologic protein adsorption) mechanism

Immune complex mechanism

An eluate reacts with only some of the panel cells tested (a partial reactivity pattern) rather than all cells. What does this most likely indicate?

-An autoantibody with panspecificity for an antigen that the patient lacks

-An alloantibody with a specific antigen target

-A technical error in the elution procedure

-Passive anti-A and anti-B from IVIG

An alloantibody with a specific antigen target

A patient's DAT is positive with anti-IgG only (anti-C3d negative). Which of the following is the most likely cause?

-Cold autoantibody or complement-mediated drug reaction

-Warm autoantibody or drug-induced antibody (immune mechanism)

-A delayed hemolytic transfusion reaction from ABO incompatibility

-Normal, expected finding requiring no further workup

Warm autoantibody or drug-induced antibody (immune mechanism)

A patient's plasma is positive by IAT and the DAT is positive, but the eluate is nonreactive against all cells tested. Which of the following best explains this pattern?

-True warm autoantibody with panreactivity

-Nonimmunologic protein adsorption (NIPA) or a drug-related mechanism

-A delayed hemolytic transfusion reaction from an alloantibody

-Warm autoantibody showing a specificity of anti-e

Nonimmunologic protein adsorption (NIPA) or a drug-related mechanism

A DAT performed with polyspecific AHG is positive. Both anti-IgG and anti-C3d monospecific reagents are also positive. Which of the following is most consistent with this pattern?

-Warm autoantibody with complement activation, mixed-type AIHA, or a delayed hemolytic transfusion reaction

-A cold agglutinin with no clinical significance

-A technical error requiring the test to be discarded

-Drug-induced hemolysis via the membrane modification (nonimmunologic protein adsorption) mechanism only

Warm autoantibody with complement activation, mixed-type AIHA, or a delayed hemolytic transfusion reaction

Which elution method uses freeze-thaw cycling to disrupt the red cell membrane and release antibody, and is best suited for cold-reactive antibody investigations?

-Acid elution

-Heat elution

-Lui freeze-thaw elution

-Chloroform elution

Lui freeze-thaw elution

A patient presents with panagglutination on the antibody screen, a positive DAT, and a panreactive eluate. What is the primary goal of further pretransfusion workup in this scenario?

- Confirm the diagnosis of WAIHA and stop all further testing

-Rule out an underlying alloantibody that may be masked by the autoantibody

-Determine the patient's exact Rh genotype

-Perform an acid elution only, since that is the only valid technique for panagglutination

Rule out an underlying alloantibody that may be masked by the autoantibody

In the drug adsorption mechanism of drug-induced immune hemolysis, what is the underlying process?

-The drug binds covalently to the RBC membrane; anti-IgG antibody forms and binds to drug-coated cell, RBCs cleared my macrophages

- Antibody and drug form immune complexes in the plasma that passively attach to red cells and activate complement

- The drug induces production of a true autoantibody indistinguishable from warm autoimmune hemolytic anemia

-The drug nonspecifically alters plasma proteins, causing them to coat the red cell membrane

The drug binds covalently to the RBC membrane; anti-IgG antibody forms and binds to drug-coated cell, RBCs cleared my macrophages

A patient's plasma is positive by IAT, the DAT is positive, and the eluate is panreactive against all screening/panel cells. What is the most likely interpretation?

-True warm autoimmune hemolytic anemia (WAIHA)

-Nonimmunologic protein adsorption (NIPA) from a drug

- A drug-dependent antibody mechanism only

-A technical error in the DAT

True warm autoimmune hemolytic anemia (WAIHA)

DTT treatment of reagent red cells is used to resolve anti-CD38 (daratumumab) interference. What important limitation must be considered when selecting donor units for a patient on anti-CD38 therapy?

-DTT treatment has no limitations and can be used for all antigen typing purposes

-DTT also destroys Kell system antigens, so K-negative units are typically selected instead of relying on DTT-treated donor cells for Kell typing

-DTT treatment permanently changes the patient's own ABO type

-DTT treatment only works on group O donor units

DTT also destroys Kell system antigens, so K-negative units are typically selected instead of relying on DTT-treated donor cells for Kell typing

Anti-CD38 therapy (e.g., daratumumab) is known to interfere with pretransfusion testing. What is the nature of this interference, and how is it typically resolved?

-It causes a false-negative antibody screen, resolved by testing with enzyme-treated cells only

-It causes panagglutination on antibody screens and panels because CD38 is expressed on reagent red cells; this can be resolved by treating reagent cells with DTT to destroy CD38

-It causes a false-positive ABO forward type, resolved by repeating with a different ABO reagent lot

-It has no effect on serologic testing and requires no special workup

It causes panagglutination on antibody screens and panels because CD38 is expressed on reagent red cells; this can be resolved by treating reagent cells with DTT to destroy CD38

What is the fundamental difference between testing a patient's plasma and testing a patient's eluate?

-Plasma and eluate always give identical results, so testing both is redundant

-Plasma detects free antibody circulating in the patient's serum, while eluate detects antibody that was actually bound to the red cell membrane

-Eluate can only be tested against the patient's own red cells

-Plasma is only useful for ABO typing, while eluate is only useful for Rh typing

Plasma detects free antibody circulating in the patient's serum, while eluate detects antibody that was actually bound to the red cell membrane

When passive ABO antibody from IVIG or platelet transfusion is suspected as the cause of a positive eluate, why should the eluate also be tested against A1 and B reverse-grouping cells rather than only standard antibody panel cells?

-Standard panel cells are all group O and would not reveal an ABO antibody, so A1 and B cells are needed to detect passively acquired anti-A or anti-B

-A1 and B cells are more sensitive to warm autoantibodies than standard panel cells

-Standard panel cells cannot be used with eluates under any circumstance

-A1 and B cells are required for all elution procedures regardless of suspected cause

Standard panel cells are all group O and would not reveal an ABO antibody, so A1 and B cells are needed to detect passively acquired anti-A or anti-B

A differential DAT is positive for both monospecific anti-IgG and monospecific anti-C3d. Which of the following is LEAST likely to explain this combined pattern?

- Nonimmunologic protein adsorption from a drug

-Mixed-type autoimmune hemolytic anemia

-A warm autoantibody with secondary complement activation

- A delayed hemolytic transfusion reaction

Nonimmunologic protein adsorption from a drug

A patient's autocontrol is positive, but the DAT is negative. What does this combination most likely indicate?

-The patient has been recently transfused with an incompatible unit

- A drug-induced immune mechanism affecting only the autocontrol

-The patient has a true autoantibody that only appears in an autocontrol format

-A technical or false-positive result in the autocontrol, rather than true antibody coating of the red cells, since the DAT directly tests washed cells

A technical or false-positive result in the autocontrol, rather than true antibody coating of the red cells, since the DAT directly tests washed cells

A warm autoantibody shows apparent specificity resembling anti-e. How can a technologist determine whether this represents a true allo-anti-e or an autoantibody with anti-e-like specificity?

-There is no reliable way to distinguish the two; both must be treated as true alloantibodies

-Perform an elution and observe whether the eluate is IgM or IgG

-Test the patient's plasma against only e-negative reagent cells

-Antigen type the patient's own red cells for the e antigen; if the patient is e-positive, the antibody cannot be a true allo-anti-e

Antigen type the patient's own red cells for the e antigen; if the patient is e-positive, the antibody cannot be a true allo-anti-e

In the drug adsorption (hapten) mechanism, the drug binds tightly to the RBC membrane and the patient produces an anti-drug IgG antibody. What is the resulting testing pattern?

-DAT positive only for complement, never for IgG

-DAT negative; plasma and panel pan-reactive regardless of drug presence

-DAT positive; plasma and panel nonreactive unless the drug is added directly to the test system (drug-dependent)

-DAT positive; plasma and eluate pan-reactive without any drug needed in testing

DAT positive; plasma and panel nonreactive unless the drug is added directly to the test system (drug-dependent)

Why might the false-positive DAT and panagglutination caused by IVIG be mistaken for a true warm autoantibody?

-The serologic pattern looks identical to true WAIHA, so the patient's medication history (recent IVIG) is the key clue distinguishing the two

-IVIG causes a distinct, easily recognizable mixed-field reaction pattern unlike WAIHA

-IVIG-induced reactivity is always weaker in strength than a true warm autoantibody, making it easy to distinguish

-IVIG only affects the DAT and never affects plasma or eluate reactivity

The serologic pattern looks identical to true WAIHA, so the patient's medication history (recent IVIG) is the key clue distinguishing the two

A patient's plasma (IAT) is negative, but the DAT is positive and the eluate is also negative. Which mechanism is most consistent with this pattern?

-A drug-dependent mechanism, where reactivity requires the drug to be present in the test system

-Passive transfer of antibody from IVIG

-True warm autoimmune hemolytic anemia

-A pre-existing alloantibody from a prior transfusion

A drug-dependent mechanism, where reactivity requires the drug to be present in the test system

A differential DAT is positive with monospecific anti-C3d only, and negative with monospecific anti-IgG. What is the best explanation for this pattern?

-A warm autoantibody that has not yet fixed complement

-An error in reagent storage temperature

-Hemolytic disease of the fetus and newborn

-A cold autoantibody (IgM) that has already dissociated at 37 C, leaving complement behind, or a drug-induced mechanism involving complement activation

A cold autoantibody (IgM) that has already dissociated at 37 C, leaving complement behind, or a drug-induced mechanism involving complement activation

If passively acquired ABO antibody (from IVIG or a non-ABO-identical platelet transfusion) is suspected as the cause of a positive DAT/eluate, why might the eluate appear nonreactive against a standard antibody identification panel, and how should it instead be tested?

-Standard panel cells are group O and lack A/B antigens, so the eluate should instead be tested against A1 and B reverse-typing reagent cells

-The eluate should be diluted 1:10 before retesting against the same panel cells

-Standard panel cells are too old to react reliably, so fresh screening cells should be substituted

-Standard panel cells cannot ever be used with any eluate, regardless of suspected cause

Standard panel cells are group O and lack A/B antigens, so the eluate should instead be tested against A1 and B reverse-typing reagent cells

A warm autoantibody shows anti-e-like specificity in a patient who types as e-positive. Is e-negative blood required for transfusion, and why or why not?

-Yes, it is always required, because e-positive patients cannot receive any e-positive blood

-No, because autoantibodies never have clinical significance for transfusion

-Yes, because e-negative blood is the only blood compatible with a positive DAT

-No, it is not strictly required since the patient is not truly alloimmunized to an antigen they possess, though site policy may vary

No, it is not strictly required since the patient is not truly alloimmunized to an antigen they possess, though site policy may vary

A patient's DAT is positive, and both the plasma and eluate are pan-reactive with all panel cells, with no drug needed in the test system to produce this reactivity. Which drug-induced mechanism does this describe, and how does it differ serologically from idiopathic WAIHA?

-Membrane modification (NIPA); this pattern always resolves within 24 hours of stopping the drug

-Autoantibody induction (drug-independent); this pattern is serologically indistinguishable from idiopathic WAIHA, so drug history and temporal relationship to the medication are the distinguishing clues

-Drug adsorption (hapten) mechanism; this pattern is easily distinguished from WAIHA by a negative DAT

-Immune complex mechanism; this pattern only occurs with IgM antibodies

Autoantibody induction (drug-independent); this pattern is serologically indistinguishable from idiopathic WAIHA, so drug history and temporal relationship to the medication are the distinguishing clues

A patient has a positive DAT, but the prepared eluate is nonreactive against a standard antibody identification panel composed of group O reagent cells. Which of the following is the most likely explanation, keeping in mind that standard panel cells lack A and B antigens?

-The patient must have a true warm autoantibody that failed to elute properly

-The elution technique used was necessarily the wrong one for this patient

-The antibody present is an ABO antibody (e.g., anti-A or anti-B), which would not react against group O panel cells

-The DAT result is a certain technical error and should be disregarded

The antibody present is an ABO antibody (e.g., anti-A or anti-B), which would not react against group O panel cells

A DAT is positive for complement (C3d) only, with a negative anti-IgG result. Should an elution be performed? Explain.

- No, because elutions can only be performed on IgG-negative, C3d-negative cells

-Yes, because C3d-coated cells always carry co-bound IgG that must be recovered

-Yes, but only using the heat elution method

-No, because a C3d-only positive DAT implies an IgM antibody was bound in vivo and has already dissociated, leaving no IgG remaining to elute

No, because a C3d-only positive DAT implies an IgM antibody was bound in vivo and has already dissociated, leaving no IgG remaining to elute

What is the purpose of performing an elution?

-To dissociate antibody from a patient's sensitized red cells so it can be tested in a panel to determine specificity

-To convert an IgM antibody into an IgG antibody for easier detection

-To permanently destroy any antibody bound to the red cell membrane

-To wash red cells prior to ABO typing only

To dissociate antibody from a patient's sensitized red cells so it can be tested in a panel to determine specificity

Which of the following statements correctly distinguishes a drug-dependent from a drug-independent antibody mechanism?

-There is no meaningful distinction; both terms describe the same serologic pattern

-A drug-independent antibody can only be detected using heat elution

-A drug-dependent antibody is always more clinically severe than a drug-independent antibody

-A drug-dependent antibody requires the drug to be present in the test system to produce a reaction in vitro, while a drug-independent antibody reacts like a true autoantibody with no drug needed in testing

A drug-dependent antibody requires the drug to be present in the test system to produce a reaction in vitro, while a drug-independent antibody reacts like a true autoantibody with no drug needed in testing

A patient's plasma (IAT), DAT, and eluate are all positive, with the eluate reacting against all panel cells tested (pan-reactive). What is the most likely cause?

-A drug-dependent mechanism only

-Nonimmunologic protein adsorption (NIPA)

-True warm autoantibody (WAIHA)

-Passively acquired anti-A or anti-B

True warm autoantibody (WAIHA)

Why does a high-titer warm autoantibody frequently cause panagglutination on the antibody screen, panel, and crossmatched units?

-The autoantibody activates complement so strongly that it lyses all reagent red cells during testing

-Panagglutination only occurs when a true alloantibody to a high-frequency antigen is present

-The patient's red cells become saturated with autoantibody, and excess autoantibody circulates freely in the plasma, reacting with essentially all reagent and donor cells

-Panagglutination indicates the patient's plasma contains no antibody at all

The patient's red cells become saturated with autoantibody, and excess autoantibody circulates freely in the plasma, reacting with essentially all reagent and donor cells

Which of the following is NOT a recognized cause of a positive DAT?

-Nonspecific passive adsorption of IgG in a patient with hypergammaglobulinemia

-A first-time blood donation from a healthy, non-medicated volunteer donor

-Hemolytic disease of the fetus and newborn

-Passively acquired antibody from IVIG or a recent platelet transfusion

A first-time blood donation from a healthy, non-medicated volunteer donor

What is the fundamental difference in what the DAT and the IAT each detect?

-The DAT detects free antibody in plasma, while the IAT detects antibody already bound to red cells

-The DAT is only used for donor units, while the IAT is only used for patient samples

-The DAT detects antibody/complement already bound to red cells in vivo, while the IAT detects free antibody in plasma reacting with reagent cells in vitro

-The DAT and IAT both detect the same thing but use different incubation temperatures

The DAT detects antibody/complement already bound to red cells in vivo, while the IAT detects free antibody in plasma reacting with reagent cells in vitro

A patient's antibody screen, panel cells, and crossmatched donor units are all reactive at the AHG phase, the DAT is positive for IgG, and the eluate is also reactive with all panel cells tested. What is the most likely explanation, and what is the primary goal of further workup?

-This is a delayed hemolytic transfusion reaction; the goal is to notify the blood supplier immediately

-This is a true warm autoantibody (WAIHA); the goal is to determine whether a clinically significant alloantibody is masked underneath the autoantibody

-This is a technical error; the goal is to repeat testing with fresh reagents

-This is a cold autoantibody; the goal is to perform prewarmed testing only

This is a true warm autoantibody (WAIHA); the goal is to determine whether a clinically significant alloantibody is masked underneath the autoantibody

A patient's plasma and eluate are both nonreactive at all phases, but the patient is on high-dose penicillin therapy and has a positive DAT. What should be considered instead of a true warm autoantibody?

-The DAT result should be dismissed as a laboratory error with no further action

-A cold autoantibody should automatically be assumed

-A drug-related mechanism should be considered given the negative plasma/eluate reactivity and the implicated medication

-The patient must have an undetected alloantibody to a low-frequency antigen

A drug-related mechanism should be considered given the negative plasma/eluate reactivity and the implicated medication

A patient recently received IVIG therapy. Her DAT is now positive, and her plasma and acid eluate both show panagglutination resembling a warm autoantibody. What is the most likely explanation?

-The panagglutination proves the patient has true, idiopathic WAIHA unrelated to the IVIG

-IVIG destroys the patient's own red cell antigens, causing panagglutination through antigen loss

-IVIG is a purified IgG product that can cause a false-positive DAT and mimic a warm autoantibody in vitro, producing panagglutination in both plasma and eluate

-IVIG can only cause a positive DAT if administered intravascularly at a rapid rate

IVIG is a purified IgG product that can cause a false-positive DAT and mimic a warm autoantibody in vitro, producing panagglutination in both plasma and eluate

A patient's DAT is positive, and the plasma and panel cells are nonreactive UNLESS the suspected drug is added directly to the test system, at which point strong reactivity is seen. Which drug-induced mechanism does this describe?

-Mixed-type autoimmune hemolytic anemia

-Drug adsorption (hapten) mechanism, which is drug-dependent

-Membrane modification (NIPA)

-Autoantibody induction, which is drug-independent

Drug adsorption (hapten) mechanism, which is drug-dependent

An eluate reacts with all panel cells tested, showing pan-reactivity. What is the most likely interpretation?

-Evidence of a drug-independent mechanism that requires no further workup

-Consistent with a warm autoantibody

-Consistent with a single, specific alloantibody

-Evidence the DAT result was a false positive

Consistent with a warm autoantibody

Some manufactured IVIG lots have been reported to contain unexpected antibodies. Which of the following is specifically named as a concern?

-Anti-K, which requires K-negative units for all IVIG recipients

-Anti-Jka, which requires Kidd phenotyping before every IVIG infusion

-Anti-A and anti-B, which can produce a positive DAT in the recipient

-Anti-D, which mandates Rh-immune globulin administration

Anti-A and anti-B, which can produce a positive DAT in the recipient

A patient's autocontrol and DAT are both positive. The patient was transfused two units of red blood cells four days ago. What important alternative explanation should be considered before concluding the patient has a true autoantibody?

-The patient must have received an ABO-incompatible unit

-The autocontrol is not a valid test to perform on a recently transfused patient

-The DAT is always falsely positive within one week of transfusion and should be disregarded entirely

-The result may simply reflect transfused donor cells coated with an alloantibody the patient is actively producing, rather than a true autoantibody

The result may simply reflect transfused donor cells coated with an alloantibody the patient is actively producing, rather than a true autoantibody

For a patient on daratumumab (anti-CD38) therapy, DTT-treated reagent red cells can eliminate the panagglutination interference. Why can DTT-treated cells NOT be used to rule out anti-K, and what is typically done instead?

- DTT treatment also destroys Kell system antigens, so K-negative units are typically provided instead (unless the patient is known to be K-positive)

-DTT treatment has no effect on Kell antigens, so this concern does not actually apply

-DTT treatment converts Kell-positive cells to Kell-negative cells permanently in the donor pool

-DTT-treated cells can be used for Kell typing without any limitation

DTT treatment also destroys Kell system antigens, so K-negative units are typically provided instead (unless the patient is known to be K-positive)

A patient with an anti-e-like warm autoantibody (and who is e-positive) is transfused with e-negative units anyway. What is a potential disadvantage of this approach?

-E-negative units carry a significantly higher risk of transfusion-transmitted infection

-E-negative units cannot be crossmatched using the antiglobulin technique

-Since e-negative units are also E-positive, repeated transfusion of E-positive blood could induce a true allo-anti-E

-E-negative units are never available from the blood supplier

Since e-negative units are also E-positive, repeated transfusion of E-positive blood could induce a true allo-anti-E

What is the purpose of testing the supernatant from the last (final) wash step before performing an elution, and what result should it show?

-It confirms the patient's ABO type before elution proceeds

-It is used to select which elution technique will be used

-It is tested as a negative control; it must test negative to prove that eluate reactivity reflects antibody truly bound to the red cells rather than residual, incompletely washed plasma antibody

-It is tested as a positive control; it must test positive to confirm the wash steps did not remove too much antibody

It is tested as a negative control; it must test negative to prove that eluate reactivity reflects antibody truly bound to the red cells rather than residual, incompletely washed plasma antibody

Explain the fundamental difference between testing a patient's plasma and testing a patient's eluate.

-Plasma detects free-floating antibody not attached to red cells (via IAT), while an eluate is prepared to recover antibody that was actually bound to (coating) the patient's red cells

-Plasma and eluate are functionally identical and should always show the same reactivity pattern

-Plasma can only be used to type for ABO antigens, while eluate can only be used for Rh antigens

-Eluate testing replaces the need for an antibody screen entirely

Plasma detects free-floating antibody not attached to red cells (via IAT), while an eluate is prepared to recover antibody that was actually bound to (coating) the patient's red cells

A patient's antibody screen, panel cells, and crossmatched donor units are all reactive at the AHG phase, the DAT is positive for IgG, and the eluate is also reactive with all panel cells tested. What is the most likely explanation, and what is the primary goal of further workup?

-This is a delayed hemolytic transfusion reaction; the goal is to notify the blood supplier immediately

-This is a true warm autoantibody (WAIHA); the goal is to determine whether a clinically significant alloantibody is masked underneath the autoantibody

-This is a cold autoantibody; the goal is to perform prewarmed testing only

-This is a technical error; the goal is to repeat testing with fresh reagents

This is a true warm autoantibody (WAIHA); the goal is to determine whether a clinically significant alloantibody is masked underneath the autoantibody

A differential DAT is positive with monospecific anti-C3d only, and negative with monospecific anti-IgG. What is the best explanation for this pattern?

-Hemolytic disease of the fetus and newborn

-A warm autoantibody that has not yet fixed complement

-A cold autoantibody (IgM) that has already dissociated at 37 C, leaving complement behind, or a drug-induced mechanism involving complement activation

-An error in reagent storage temperature

A cold autoantibody (IgM) that has already dissociated at 37 C, leaving complement behind, or a drug-induced mechanism involving complement activation

In the membrane modification (nonimmunologic protein adsorption, NIPA) mechanism, the drug alters the RBC membrane so that plasma proteins adsorb nonspecifically. What testing pattern results?

-DAT positive; plasma and eluate both react only when the drug is added to the test system

-DAT negative; eluate strongly pan-reactive

-DAT positive only with monospecific anti-IgG, never with anti-C3d

-DAT positive; eluate typically nonreactive since no true antibody to the drug or red cell is produced

DAT positive; eluate typically nonreactive since no true antibody to the drug or red cell is produced

In the immune complex mechanism, the drug loosely binds an RBC membrane protein, forming a drug-protein complex against which the patient produces IgG and/or IgM. What is a hallmark clinical feature of this mechanism?

-It rarely activates complement and causes only mild, chronic extravascular hemolysis

-The DAT is often positive for complement, and it can cause acute intravascular hemolysis; this mechanism is also drug-dependent

-It always produces a pan-reactive eluate identical to idiopathic WAIHA

-It exclusively affects platelets rather than red cells

The DAT is often positive for complement, and it can cause acute intravascular hemolysis; this mechanism is also drug-dependent

How does anti-CD47 (magrolimab) interference differ from anti-CD38 (daratumumab) interference in pretransfusion testing?

-Anti-CD47 and anti-CD38 produce identical interference patterns and require identical resolution strategies

-Anti-CD47 only affects platelet crossmatching and has no effect on red cell serology

-Anti-CD47 DOES interfere with ABO typing, and CD47 is not destroyed by DTT treatment, requiring allogeneic adsorption or specialized reagents for mitigation

-Anti-CD47 does NOT interfere with ABO typing, unlike anti-CD38

Anti-CD47 DOES interfere with ABO typing, and CD47 is not destroyed by DTT treatment, requiring allogeneic adsorption or specialized reagents for mitigation

A patient receiving daratumumab (anti-CD38) for multiple myeloma shows panagglutination on the antibody screen and panel. What causes this interference, and what does it NOT affect?

-Weak CD38 expression on reagent/donor red cells causes the panagglutination, but it does not interfere with ABO/D typing or an immediate-spin crossmatch

-The drug causes complement-mediated lysis of all reagent red cells tested

-The interference only occurs with monospecific anti-C3d reagents and never with anti-IgG

-The drug directly binds reagent red cell antigens, and it also interferes with ABO forward typing

Weak CD38 expression on reagent/donor red cells causes the panagglutination, but it does not interfere with ABO/D typing or an immediate-spin crossmatch

A patient with a warm autoantibody was transfused 2 units of red blood cells 10 days ago. Why is autologous adsorption NOT appropriate in this case?

-Autologous adsorption cannot remove IgG-class autoantibody

-Circulating donor cells could adsorb out a true alloantibody, causing it to be missed

-The patient's hematocrit is always too low shortly after transfusion

-Autologous adsorption only works on IgM antibodies

Circulating donor cells could adsorb out a true alloantibody, causing it to be missed

Mixed-type autoimmune hemolytic anemia is defined by:

-A DAT that is positive for complement (C3d) only

-The simultaneous presence of both a warm (IgG) autoantibody and a pathologic cold (IgM) autoantibody in the same patient

-An autoantibody that reacts exclusively at temperatures below 4 C

-A negative DAT together with a positive antibody screen

The simultaneous presence of both a warm (IgG) autoantibody and a pathologic cold (IgM) autoantibody in the same patient

Which testing method is unaffected by circulating IgG or transfused donor cells and can be used when serologic phenotyping is unreliable in a WAIHA patient?

-Enzyme panel testing

-Molecular (genotype) testing

-Saline replacement technique

-Prewarmed antibody screening

Molecular (genotype) testing

Which laboratory finding, beyond the DAT itself, correlates with the severity of hemolysis in a patient with WAIHA?

-Elevated haptoglobin

-Decreased LDH

-Elevated indirect bilirubin

-Decreased reticulocyte count

Elevated indirect bilirubin

A patient's plasma is pan-reactive due to a warm autoantibody. After appropriate allogeneic adsorption, the adsorbed plasma reacts with 7 of 11 panel cells, all of which are Jk(a+), while the remaining antibodies have adequate rule-outs. What does this result suggest?

-The adsorption procedure failed completely and must be repeated from the start

-An underlying alloantibody, likely anti-Jka, that had been masked by the autoantibody before adsorption

-A cold-reacting autoantibody is also present in the plasma

-The patient's own red cells must be Jk(a+)

An underlying alloantibody, likely anti-Jka, that had been masked by the autoantibody before adsorption

Why are R1R1, R2R2, and rr (R0R0) cells specifically chosen as the standard set of allogeneic adsorbing cells?

-They are the only red cell phenotypes commercially available for adsorption

-Together, with attention to other non-Rh antigen systems, they provide broad coverage so a true alloantibody is not inadvertently adsorbed out along with the autoantibody

-They completely lack Kell system antigens, preventing false-positive Kell reactions

-AABB standards require this exact phenotype combination for all adsorption procedures

Together, with attention to other non-Rh antigen systems, they provide broad coverage so a true alloantibody is not inadvertently adsorbed out along with the autoantibody

A single round of adsorption does not fully remove reactivity from a patient's plasma containing a strong warm autoantibody. What is the appropriate next step?

-Report the antibody screen as unresolved and proceed directly to crossmatch

-Switch immediately to cold autoadsorption instead

-Perform additional rounds of adsorption using fresh adsorbing red cells

-Increase the incubation temperature to 45 C to strengthen adsorption

Perform additional rounds of adsorption using fresh adsorbing red cells

Which of the following conditions classically presents with a NEGATIVE DAT, distinguishing it from WAIHA, CAIHA, and PCH?

-Cold agglutinin disease (CAD)

-Paroxysmal cold hemoglobinuria (PCH)

-Paroxysmal nocturnal hemoglobinuria (PNH)

-Warm autoimmune hemolytic anemia (WAIHA)

Paroxysmal nocturnal hemoglobinuria (PNH)

Complement-mediated hemolysis can result in either extravascular or intravascular red cell destruction, depending on:

-The patient's ABO blood type

-How far the complement cascade progresses before activation stops

-Whether the causative antibody is IgG or IgM

-The temperature at which the antibody reacts optimally

How far the complement cascade progresses before activation stops

A 62-year-old woman with a history of CLL presents with a hemoglobin of 7.2 g/dL, elevated LDH and indirect bilirubin, low haptoglobin, and a DAT positive for IgG only; her antibody screen, panel cells, and autocontrol are all reactive at the AHG phase. What is the most likely diagnosis?

-Cold agglutinin disease

-Warm autoimmune hemolytic anemia, likely secondary to her CLL

-Paroxysmal cold hemoglobinuria

-Paroxysmal nocturnal hemoglobinuria

Warm autoimmune hemolytic anemia, likely secondary to her CLL

After incubating a patient's plasma with adsorbing red cells and separating the supernatant, what should the adsorbed plasma ideally contain?

-The autoantibody, but no alloantibody

-Any underlying alloantibody (if present), but the autoantibody should no longer be present

-Neither antibody, regardless of what was originally present

-Both antibodies, but at a reduced titer

Any underlying alloantibody (if present), but the autoantibody should no longer be present

Before treating a recently transfused WAIHA patient's red cells with CDP or EGA for phenotyping, what should be performed first, and why?

-A prewarmed panel, to rule out a cold-reacting antibody

-An elution, to identify the antibody coating the cells

-A cell separation procedure, to recover the patient's own autologous reticulocytes rather than typing circulating donor cells

-An antibody titration, to determine the strength of the autoantibody

A cell separation procedure, to recover the patient's own autologous reticulocytes rather than typing circulating donor cells

A MLS needs to antigen type a WAIHA patient's red cells for the K antigen, but only EGA-treated cells are available. What should the MLS do?

-Proceed with EGA-treated cells, since EGA does not affect Kell system antigens

-Avoid using EGA for Kell typing, since it denatures Kell antigens, and use an alternative method such as CDP treatment or molecular testing

-Use the EGA-treated cells but repeat the test three times to confirm the result

-Treat the cells with ZZAP first, since ZZAP and EGA have identical effects on Kell antigens

Avoid using EGA for Kell typing, since it denatures Kell antigens, and use an alternative method such as CDP treatment or molecular testing

What is ZZAP, and what is its purpose in the autoadsorption procedure?

-A monoclonal antibody that inhibits complement activation on red cells

-A combination of DTT and papain that strips in vivo-bound autoantibody and increases the cells' adsorptive capacity

-A lectin reagent used to differentiate A1 from A2 red cells

-A wash solution used only to check the last wash before elution

A combination of DTT and papain that strips in vivo-bound autoantibody and increases the cells' adsorptive capacity