High Yield Study guide for antibody screening docx

ANTIBODY SCREENING
Antibody Screening- focused in detecting
irregular or unexpected antibodies
Immune alloantiboides- unexpected antibodies
of primary importance made in response to
stimulation from RBCs
Naturally occurring antibodies- results from
exposure to environmental sources, such as
pollen, fungus, and bacteria that have similar
structures with RBCs
Passively acquired antibodies- produced in one
individual and then transmitted to another via
plasma-containing blood components
Clinically significant antibodies- cause
decreased survival of RBCs with the target
antigen. Usually are IgG that react at 37oC or in
the AHG phase
Autoantibodies may interfere the detection of
clinically significant antibodies
Autoantibodies may mask the presence of
clinically significant antibodies because it reacts
with all RBCs tested
After antibody screening, antibody detection
must be done
Antibody Screening
1. Tube method- traditional method
2. Gel method
3. Solid Phase Adherence Method
Tube method
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Uses IAT as it method of testing
RBC Reagents
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All RBC reagents used in the antibody
screen come from group O individuals
typed for the most common and
significant RBC antigens. Group O cells
are so Anti-A and Anti-B will not
interfere
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Screen cells are packaged in 2 or 3 cell
suspensions
Ideally there should be homozygous
expression of many of the antigens to
show dosage
Enhancement Reagents
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22% albumin- reduce zeta potential
LISS- reduces zeta potential and
increases the uptake of antibody onto
the RBC during sensitization
PEG- centrifugation not performed to
prevent nonspecific aggregation
AHG Reagents
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Polyspecific AHG reagent is used.
Contains IgG and complement
components, preferably anti-C3d
Coomb’s control cells are Rh-positive
RBCs that have been coated with anti-D
Gel Method
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Microtuble filled with dextran
acrylamide gel
Card is incubated at 37oC for 15 minutes
to 1 hour
Centrifuged for 10 minutes
Agglutinated cells are trapped in the gel
Negative reaction is when RBCs are at
the bottom of the microtubule
Solid Phase Adherence Method
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Serum is added to the well with screen
cells with LISS
Incubated at 37oC
Wells are washed to remove unbound
antibodies
No AHG reagent, instead indicator red
cells coated with anti-IgG are added
Centrifuge
If sensitization occur, indicator cells
react with the antibodies bound to the
ANTIBODY SCREENING
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RBCs coating the microtiter well,
forming a diffuse pattern
Negative if indicator cells form a pellet
at the bottom of the well
Smaller sample size is required, making
it ideal for pediatric settings
Notes to remember
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Different reaction phases may mean
different classes of antibodies
If the autocontrol is positive,
autoantibody should be suspected
A single antibody should be suspected
when all screen cells yield a positive
reaction in the same phase with the
same strength
Multiple antibodies when it reacts with
different strengths and phases
Mf reactions are associated with antiSda, and Lutheran antibodies
Limitations
Factors that may affect the limitations are cellto-serum ratio, temperature and phase of
reactivity, length of incubation and pH
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