BB 6: AGT/AHG Test

the ____ test provides a bridging molecule that bridges RBCs together to help make hemagglutination visible for IgG.

AHG

the ____ reagent is an Ab solution made from immunized animals (e.g., rabbit) that makes human IgG or C’ Abs that bind to human immunoglobulins found attached to human RBCs.

AHG

which type of AHG test refers to the following:

• measures in vivo sensitization of the RBCs

• sensitization occurs inside the body

DAT

which type of AHG test refers to the following:

• measures in vitro sensitization of the RBCs

• sensitization occurs outside the body

• e.g., antibody screen test (ABS) or Ab ID panel (antibody identification)

IAT

the following are ____ clinical conditions.

• HDFN

• HTR

• AIHA

DAT

which DAT clinical condition refers to maternal IgG crosses placenta barrier and binds to infant RBCs (up to 4+ reaction)?

HDFN

which DAT clinical condition refers to transfused recipient Ab binds to donor RBCs?

HTR

which DAT clinical condition refers to a medical condition or drug induced phenomenon that creates Abs towards RBCs (e.g., IgM = cold and IgG = warm)?

AIHA

the following procedure describes the ____ test:

• wash unknown RBCs at least 3x with saline (remove unbound globulins)

• add polyspecific AHG reagent (binds to IgG and/or C3d bound to patient RBCs

• centrifuge (accelerates agglutination) and read

• grade (0-4+) and record agglutination

DAT

to all ____ DAT test results, add reagent Coombs’ Check Cells (CCCs)/Check Cells (CCs) (antibody coated RBCs).

negative

____ are used to verify:

• washing was adequately performed

• that AHG was added

• that the AHG reagent is working properly

check cells

for DAT, if a CC reaction is ____, the test is valid.

positive

for DAT, if a CC reaction is ____, the test is invalid and must be repeated.

negative

when the ____ AHG test result is a positive reaction, the result only tells you that either IgG or C’ is present on the patient’s RBCs or BOTH elements are present.

polyspecific

to see whether IgG or C’ is present on the patient’s RBCs after a positive polyspecific DAT, the DAT must be repeated using ____ AHG reagents.

monospecific

a positive ____ reaction, consider:

• evidence of in vivo Abs attached to RBCs

• recently transfused

• medical condition

• medication

DAT

saline washing of RBCs (critical) to completely remove any residual serum proteins that could neutralize the sensitized ____ reagent.

AHG

addition of ____ reagent (proper amount or inadvertent omission) affect the the DAT test.

AHG

____ reagent integrity is maintained/is working properly is a common factor that affects the DAT.

AHG

____ is present due to:

• IgM Ab present

• CHD (Cold Hemagglutinin Disease)

• PCH (Paroxysmal Cold Hemoglobinuria)

• C’ binding IgG present

C3d

which AHG test promotes the following:

• safe and effective RBC transfusion

• RBC longevity to maintain oxygen-carrying capacity to vital organs

• normal body functions without compensations

  • e.g., tachycardia, hyperventilation, etc.

IAT

which AHG test avoids the following:

• transfusion of incompatible RBCs

• decreased survival of the donor RBCs

• clinical effects of a HTR (causing morbidity/mortality)

IAT

during an IAT, RBCs are incubated with patient ____ to allow time for the antibody to attach to the RBC antigen.

sera

during an IAT, at least 3 saline washes are performed to remove free ____ molecules.

globulin

during an IAT, ____ reagent is added to form RBC agglutinates (RBC antigen + antibody + anti-IgG antibody + RBC antigen).

AHG

during an IAT, centrifugation is necessary to accelerate ____ to bring cells together.

agglutination

during an IAT, check cells are added to all ____reactions to check for neutralization (by free globulin molecules) or inadvertent omission of Coombs’ reagent or integrity of Coombs’ reagent.

negative

the following are factors that could affect ____

• Serum:Cell Ratio (SC ratio)

• reaction media

• temperature

• incubation time

• washing of RBCs

• addition of AHG

• centrifugation

IAT

the commonly used ____ is 2 drops of patient serum + 1 drop of enhancement media reagent.

SC ratio

increased ____ uses 4-6 drops (no enhancement media used) + 1 drop of reagent).

SC ratio

DAT or IAT: detects in vivo IgG and/or complement to patient RBCs?

DAT

DAT or IAT: one stage procedure?

DAT

DAT or IAT: patient’s RBCs tested with AHG without incubation?

DAT

DAT or IAT: tests for certain clinical conditions (e.g., HDFN, HTR)?

DAT

DAT or IAT: detects in vitro via test of Abs in patient sera, allowing IgG and/or C’ to bind to reagent RBCs?

IAT

DAT or IAT: two stage procedure?

IAT

DAT or IAT: requires incubation before addition of AHG?

IAT

DAT or IAT: tests for presence or absence of clinically significant Abs in patient sera that affects compatibility to transfusing RBCs?

IAT

when scoring values, a 4+ would equate a score of ____.

12

when scoring values, a 3+ would equate a score of ____.

10

when scoring values, a 2+ would equate a score of ____.

8

when scoring values, a 1+ would equate a score of ____.

5

when scoring values, a W+ would equate a score of ____.

2

which type of AHG reagent is clear?

polyspecific

which type of AHG reagent contains Abs to human IgG and human C’ (C3d)?

polyspecific

which type of AHG reagent has the advantage of detecting C’-binding Abs on RBCs (e.g., Jka)?

polyspecific

which type of AHG reagent has the disadvantage of detecting C’ on cells that may not be clinically significant (nuisance reactions)?

polyspecific

for monospecific AHG reagent, what is green?

IgG

for monospecific AHG reagent, what is clear?

C3d

which type of AHG reagent has fewer nuisance positives and very specific in target either IgG or C3d?

monospecific

for AHG reagent preparation, what refers to animal hyper-immunized with human globulins, bled for antisera to obtain high titer, high avidity specificity to human globulin?

polyclonal

for AHG reagent preparation, what refers to the use hybridoma cells from mice; collection of cultures or ascites fluid yields antisera?

monoclonal

check cells are reagent RBCs coated with IgG that are added to all ____ AHG test results.

negative

____ are used to check for:

• adequate washing of RBCs used to detect Ab or C’

• ensures Coombs’ reagent was addded

• ensures Coombs’ reagent is working properly

check cells

the following may cause a false ____ result for AHG tests:

• dirty glassware

  • glass bits inside tube

  • broken tubes in box

• bacterial contamination of cells or saline

• over-centrifugation and over-reading

• polyagglutinable cells

• reagent contamination

• saline contaminated by heavy metals or colloidal silica

positive

false ____ results may occur due to a refrigerated specimen or a clotted sample (due to C’ attachment).

positive

cells with positive DAT used for IAT (e.g., autocontrol) may cause false ____ results for AHG tests.

positive

the following may cause a false ____ result for AHG tests:

• inadequate or improper washing of cells

• AHG reagent not added

• neutralization of AHG reagent due to inadequate washing

• deterioration of AHG reagent

negative

the following may cause a false ____ result for AHG tests:

• under-centrifugation or over-centrifugation

• in test tube: testing error, CLS may shake tube too hard

• patient serum not added in IAT

negative