MICROWAVE DISSOCIATION OF ANTIGEN-ANTIBODY COMPLEXES - A NEW ELUTION TECHNIQUE TO PERMIT PHENOTYPING OF ANTIBODY-COATED RED-CELLS

To evaluate the effectiveness of microwave irradiation in dissociating IgG from red cells (RBCs), the use of chloroquine diphosphate (CDP) w as compared to that of microwaves. Fifteen paired samples of RBCs from 15 patients with positive direct antiglobulin tests (DATs) were treat ed with both CDP and microwave radiation. Total microwave exposure tim es ranged f rom 20 to 100 seconds. Posttreatment DATs were performed, and the reaction grades of the posttreatment DATs were compared. RBC p henotyping was also performed on repeatedly microwaved RBCs to demonst rate possible effects on RBC antigen expression. Microwaves successful ly reduced the reaction grade of the DAT in 14 of 15 samples; CDP redu ced the reaction grade in 12 of 15 samples. In samples with a DAT of 2 + or greater (n = 13), the microwave method yielded a greater reductio n in DAT strength in six cases (results in the other 7 cases were iden tical with both methods) (p = 0.01). Five of eight cases with a DAT of 3+ showed a greater reduction in the DAT with microwave treatment tha n with CDP treatment; results in the remaining three cases were identi cal (p = 0.03). RBC antigenicity remained unchanged after exposure to microwave radiation (A, B, C, c, D, E, e, Fy(a), Fy(b), Jk(a), Jk(b), K, k, S, and s). Microwave treatment required less than 1 0 minutes pe r sample, while CDP treatment required 30 to 120 minutes per sample (m ean, 88 min). The microwave technique of antigen-antibody dissociation from RBCs provides a rapid and accurate method of facilitating the ph enotyping of RBCs coated with warm autoantibodies and is superior to o ther methods, which destroy RBC antigens. The microwave procedure is p referable to CDP treatment in patients with a DAT of 2+ or greater or when rapid results are desired.