Monocyte-mediated haemolysis: influence of antibody concentration on the inhibition of antibody-dependent lysis of human A1B erythrocytes by large numbers of unsensitized erythrocytes.
Antibody-dependent monocyte-mediated haemolysis of human group A1B erythrocytes was inhibited by O, Rh/D/-ve unsensitized erythrocytes. Effector cells were sterically isolated to prevent binding, recognition, and subsequent lysis of target cells. Reduction of cytotoxicity was strongest when only B, intermediate when only A1 antigens were saturated, whereas haemolysis could not be significantly inhibited by 200-fold excess of inhibitor cells if both A1 and B antigens were simultaneously saturated. Dilution of anti-A,B serum of between 1:32-1:512 did not reduce cytotoxicity in the absence of inhibitor cells, while inhibition of cytotoxicity grew proportionally stronger by every dilution step in the presence of inhibitor cells. If effector cells were immobilized by adherence, inhibition was strong and could not be influenced by the sensitizing antibody concentration. It was concluded that motility of monocytes was influenced by the number of sensitized antibody binding sites.
D000017:ABO Blood-Group System; D000906:Antibodies / Q000276:immunology*; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects*; D001666:Binding Sites, Antibody; D004306:Dose-Response Relationship, Immunologic; D004912:Erythrocytes / Q000276:immunology*; D006461:Hemolysis; D006801:Humans; D009000:Monocytes / Q000276:immunology*
D000017:ABO Blood-Group System; D000906:Antibodies