1. Part III.
Essentials of Pretransfusion Testing

2. Chapter 07.
Antibody detection and identification

3. Antibody detection and identification
O atypical or unexpected antibody:
- antibodies other than ABO antibodies (transfusion, pregnancy, delivery)
- alloantibodies (directed to a nonself-antigen)
* autoantibody
(1) Antibody Detection (Antibody Screening Test)
O determine whether an antibody to a red cell antigen has been made
- patients requiring transfusion
- women who are pregnant
- patients with suspected transfusion reactions
- blood and plasma donors
O incubating the patient's serum or plasma with screening cells
performing IAT for the detection of IgG antibodies
- screening cell: group O reagent red blood cells that provide a combination
of antigens other than A and B antigens
- antigram: lists antigens present in the reagent red blood cell suspension
Fig. 7-1

4. Antibody detection and identification

5. Antibody detection and identification
O two- or three-cell screen
O result interpretation: Fig. 7-2
O screening: positive
-> autocontrol
DAT with patient's red cells for autoantibody screening
O potentiator: Table 7-1
O transfusion and pregnancy history, diagnosis, race, and age
(2) Antibody Identification
1. Initial Panel
O follows the detection of the antibody in the screen
O panel cell: group O reagent red cells that have been typed for most
common antigen specificities
O autocontrol: recommended
O Box 7-1

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10. Antibody detection and identification
2. Panel Interpretation: Single Antibody Specificity
O Table 7-2, Panel 7-1, 7-2
(1) autocontrol
O IAT with patient's red cells and serum and AHG
O positive result -> autoantibody, Ab against recently transfused red cells
(2) phases (reaction temperature)
O indication that the antibody is IgG or IgM
- IgM: anti-Lea, -Leb, -M, -N, -I, -P1
O reaction at different phase: more than one antibody
(3) reaction strength
- varying strength: more than one antibody, antigen dosage
(4) ruling out
(5) matching the pattern
(6) rule of three
(7) phenotyping the patient
- test the patient's red cells to ensure they are negative for the antigen
corresponding to the identified antibody

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15. Antibody detection and identification
3. Multiple Antibodies
O Panel 7-3, 4, 5
O selected cell: used for complete the requirements for the rule of three
- donor number or code
O proteolytic enzyme:
- Fya, Fyb, S, M, N: antigenic activity -> eliminated
- Rh, Kidd, Lewis: antigenic activity -> enhanced
O one-stage enzyme technique
two-stage enzyme technique
4. Antibodies to High-Frequency (incidence) Antigens
O Panel 7-6
O Table 7-3
O High-titer, low-avidity antibodies (HTLA)
- Box 7-2
5. Antibodies to Low-Frequency Antigens
O suspected: screen: negative, crossmatch: positive
O Box 7-3: Low-incidence antigens: Lua, Kpa

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21. Antibody detection and identification
6. Enhancing Weak IgG Antibodies
O potentiator, increasing the serum to cell ratio,
increasing incubation time
O Panel 7-7
O washing the panel cells: pH, preservatives
using panels before expiration date: Ag deteriorate with storage
suspected transfusion reaction has occurred and an Ab is beginning to
develop
7. Cold Alloantibodies
O clinically insignificant, crossmatch: need caution
O IgM: anti-Lea, -Leb, -M, -N, -I, -P1
- Le: IS, RT, AHG, M,N: dosage effect, P1: vary with the age of the cells
O Panel 7-8
O Techniques to avoid the reactivity: to perform a crossmatch
O neutralization Table7-5
O prewarm technique Box 7-4

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25. Antibody detection and identification
(3) Autoantibodies
O DAT, autocontrol -> positive
-> autoantibody, delayed transfusion reaction
O reactive with most or all cells tested
O Table 7-6
1. Cold Autoantibodies
O Panel 7-9
O related diseases: Mycoplasma pneumoniae infection
infectious mononucleosis
O determine specificity: cold panel (Fig. 7-3)
O anti-I, -H, IH
- cord blood red cell: I-negative
O avoiding cold autoantibody reactivity (Table 7-7)
O adsorption techniques
- autoadsorption
- Table 7-8

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3. Warm Autoantibodies
O Panel 7-10
O Table 7-9
O use 22% albumin as a potentiator
O anti-e antibodies -> testing e-negative panel cells
O elution
- process in which IgG antibody complexes on red cells can be
dissociated and placed into a solution to test specificity
- eluate: recovered antibody
- Table 7-10
- identification using eluate
- positive DAT, negative eluate -> antibodies to medication
O adsorption: to remove the warm autoantibody specificity from the
serum to determine whether an underlying alloantibody exists
- autologous adsorption vs differential or allogeneic adsorption

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