Part III. Essentials of Pretransfusion Testing
Chapter 07. Antibody detection and identification
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
Antibody detection and identification
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
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
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
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
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
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
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
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
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
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification 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
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification
Antibody detection and identification