title: Mechanisms of the CYNAP phenomenon: evidence in the Bw49/Bw50 model for epitopes with different spatial orientation of antibody.
abstract: The mechanism of the cytotoxic-negative, absorption-positive (CYNAP) phenomenon was studied using the model of the Bw49/Bw50 split of the BW21 antigen. Anti-Bw49 antibody bound 60% as well to Bw 50 as to Bw49 cells; however, even at a cytotoxic titer of 64 against Bw49 cells, the antibody was not cytotoxic to Bw50 Cells. At equal numbers of antibody molecules bound, the anti-Bw49 antibody activated C4 and C3, and induced lysis for Bw49 but not for the Bw50 cells. These data are consistent with a model in which different spatial orientations for shared epitopes can account for CYNAP reactivity for at least some selected Bw4/Bw6-associated splits of B locus antigens.
mesh_terms: D003176:Complement C3; D003181:Complement C4; D003602:Cytotoxicity, Immunologic; D000939:Epitopes / Q000235:genetics; D006680:HLA Antigens / Q000235:genetics; D015235:HLA-B Antigens; D006241:Haptens / Q000235:genetics; D006801:Humans; D007163:Immunosorbent Techniques; D066298:In Vitro Techniques; D007518:Isoantibodies; D008214:Lymphocytes / Q000276:immunology; D008954:Models, Biological; D008968:Molecular Conformation; D011110:Polymorphism, Genetic
chemical_list: D003176:Complement C3; D003181:Complement C4; D000939:Epitopes; D006680:HLA Antigens; D015235:HLA-B Antigens; D006241:Haptens; D007518:Isoantibodies