BISC445 Immunohematology Exam 1: Johnson

Which phenotype(s) will give rise to the Bombay phenotype?

hh only

An antigen-antibody reaction alone does not cause hemolysis. What is required for red blood cell lysis?

Complement

In transfusion medicine, most clinically significant antibodies that react at body temperature and are capable of causing transfusion reaction are of which class?

IgG

Most blood group antibodies are of what immunoglobulin class?

IgM and IgG

Bombay (Oh) individuals can be differentiated from a normal group O person because Bombay (Oh) individuals have what?

The hh genotype

What are the possible ABO phenotypes of the offspring from the mating of a group A to a group O individual?

Phenotypes: A or O

Genotypes: AO or OO

What ABH substance(s) would be found in the secretions of a group B secretor?

B and H

You are working on a specimen in the laboratory that you believe to be a Bombay phenotype. Which reactions would you expect to see in a Bombay phenotype?

No agglutination with anti-A, anti-B, anti- A,B, and anti-H

Naturally occurring antibodies that react at room temperature, activate complement and can be hemolytic are of which class?

IgM

What is the only test performed on newborns to determine ABO type?

Forward Grouping

Which ABO group contains the least amount of H substance?

Bombay (Oh) has the least, followed by type A

What is the worst complication of transfusing someone with the wrong ABO group?

Intravascular hemolysis which can result in death

What class of immunoglobulin is capable of crossing the placenta?

IgG

A woman with blood group A marries a man with blood group O. Their firstborn has blood group O. The mother's most probable genotype is:

AO

The B gene will elicit the production of an enzyme which transfers which sugar to the terminal end of the H substance?

D-galactose

In a person who demonstrates A, B, and H substances in their saliva, which genes must he/she possess?

AB

What is the difference between alloantibodies and autoantibodies?

Autoantibodies: directed against self antigens

Alloantibodies: directed vs. non-self antigens

What are the terminal sugars for H, A, and B groups?

H: L-fucose

A: N-acetyl-D-galactosamine

B: D-galactose

If a person with the Bombay phenotype needs a blood transfusion, what blood type would be most compatible?

Another Bombay (Oh) person's blood

What is the only possible phenotype of an offspring produced from two group O parents?

OO

How do you resolve rouleaux in the laboratory?

Wash patient's cells several times with saline; cord cells must be washed six to eight times to remove Wharton's jelly

An elderly patient is documented as being type O. The forward grouping is negative with anti-A and anti-B. The reverse grouping shows no reactivity with A1 cells and B cells. What can be done to correct the discrepancy?

It is possible that their antibodies may be undetectable during reverse grouping due to lower levels of anti-A and anti-B antibodies in their blood

At what age do infants begin to produce their own ABO antibodies?

After 6 months of age

The ABO group antibodies are primarily what type of antibodies?

IgM

What is the source of anti-B lectin?

Bandeiraea simplicifolia

What type of cancer is most often associated with acquired B phenomenon?

Colon cancer

An example of a technical error that can occur during ABO typing is?

Cells suspension too heavy or light, failure to add reagent, failure to follow instructions, uncalibrated centrifuge, contaminated reagents, warming during centrifugation

What are some examples of group I, II, and III discreptancies?

Group I: Newborns, elderly, leukemia patients, patients on immunosuppressive drugs, congenital agammaglobulinemia, bone marrow transplant patients, and patients whose existing ABO antibodies are diluted by plasma transfusion or exchange

Group 2: Subgroups of A, leukemias may yield weak A or B antigens, Hodgkin's diseases, Acquired B phenomenon

Group III: Elevated globulin levels (multiple myeloma, Waldenstrom's macroglobulinemia, some cases of Hodgkin's), elevated levels of fibrinogen, plasma expanders, Wharton's jelly in cord blood samples

What are ABH substances detected in secretors?

The antigens present in a person blood that is secreted

What percentage of individuals inherit the secretor gene?

80%

What is an example of a technical error that can result in an ABO discrepancy?

Failure to add reagents

What percentage of the white population has type O blood?

45%

The use of known commercial antisera (anti-A & anti-B) to detect antigens on individual red blood cells is called:

Forward Grouping

The use of known reagent on red blood cells (A1 & B cells) to detect ABO antibodies in the patient's serum is called:

Reverse Grouping

What percentage of the type A population is A2?

20%

Why is reverse grouping not performed on cord blood specimens?

Most antibodies present will be from the mother and will not be an accurate reflection of the baby's ABO group

What blood type is not possible for an offspring of AO and BO mating?

AA and BB

What is the source of anti-A1 lectin?

Dolichos biflorus; sometimes Ulex europaeus depending on the amount of H antigen available

What antibodies are formed by a Bombay individual?

Anti-A, anti-B, and H

Which blood group has the greatest amount of H antigen?

Type O