Evaluation of rapid antibody dissociation techniques

Two new antibody dissociation techniques, citric acid treatment and chloroquine diphosphate (CDP) treatment at 37 C, were evaluated for their usefulness in investigating the red cells of patients with a positive direct antiglobulin test (DAT). The techniques were compared to the ZZAP and CDP-22 C procedures for (a) removal of coating antibody prior to performing warm autoadsorptions, and (b) removal of antibody so antigen typings can be performed. Twenty patient or donor antibodies were used to sensitize red cells in vitro. Complete removal of antibody was obtained by the CDP-37 C treatment in 19 cases (95%), by ZZAP treatment in 17 cases (8 5%), by the citric acid method in 10 cases (50%), and by the CDP-22 C method in three cases (15%). The CDP-37 C treatment left all red cell antigens investigated intact, and the citric acid technique left all but Kell system antigens intact. In addition, patient red cells treated by the citric acid technique could be used to adsorb warm-reacting autoantibodies from autologous serum in 15 to 30 minutes at room temperature. Investigation of a positive DAT may be facilitated by using the citric acid and CDP-37 C treatments.