Hemolysis due to human antibody-dependent cell-mediated cytotoxicity. Lysis of erythrocytes treated with anti-D serum

Antibody-dependent cell-mediated cytotoxicity against Rh+ red blood cells was detected in human anti-D sera. We used a rapid 4-h ⁵¹Cr-release assay to show that cytotixic activity was proportional to serum concentration, incubation time and the attacking cell concentration. Attacking cells were obtained from normal human peripheral blood by Ficoll-Hypaque separation. Incubation of these lymphoid cells on a nylon column prior to the test depleted the number of phagocytic (latex-positive) cells in the effluent concomitantly with a drop in cytotoxic activity. Enrichment of the attacking cell population in mononuclear phagocytes by albumin gradient separation led to an increase in cytotoxicity. Granulocytes separated by Ficoll-Hypaque were not active in this system. Antibody activity was found in the 7S region following Sephadex G-200 fractionation of anti-D serum. Antibody activity was also studied after its elution from antiserum-coated red blood cells by diethyl ether. The eluate contained IgG and mediated cell-dependent lysis. Cell-free antiserum did not mediate lysis of coated red blood cells in the presence of complement.