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) was compared to that of microwaves. Fifteen paired samples of RBCs from 15 patients with positive direct antiglobulin tests (DATs) were treated with both CDP and microwave radiation. Total microwave exposure times ranged from 20 to 100 seconds. Posttreatment DATs were performed, and the reaction grades of the posttreatment DATs were compared. RBC phenotyping was also performed on repeatedly microwaved RBCs to demonstrate possible effects on RBC antigen expression. Microwaves successfully reduced the reaction grade of the DAT in 14 of 15 samples; CDP reduced 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 reduction in DAT strength in six cases (results in the other 7 cases were identical 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 than with CDP treatment; results in the remaining three cases were identical (p = 0.03). RBC antigenicity remained unchanged after exposure to microwave radiation (A, B, C, c, D, E, e, Fya, Fyb, Jka, Jkb, K, k, S, and s). Microwave treatment required less than 10 minutes per sample, while CDP treatment required 30 to 120 minutes per sample (mean, 88 min). The microwave technique of antigen-antibody dissociation from RBCs provides a rapid and accurate method of facilitating the phenotyping of RBCs coated with warm autoantibodies and is superior to other methods, which destroy RBC antigens.(ABSTRACT TRUNCATED AT 250 WORDS)