title: Neoantigen of the complement membrane attack complex of cytotoxic human peripheral blood lymphocytes.
abstract: Neoantigenic determinants (neoAg) specific for the assembling membrane attack complex (MAC) of complement were detected by immunofluorescence microscopy on the surface of cytotoxic lymphocytes during the antibody-dependent cellular cytotoxicity (ADCC) reaction. This study employed antibody-sensitized chicken erythrocytes as target cells, human peripheral blood lymphocytes as effector cells, and RITC-conjugated rabbit F(ab')2-anti-neoAg. NeoAg was present on 60% of ADCC plaque-forming lymphocytes (PFL). Eight out of 182 neoAg-positive PFL were observed in direct contact with their target cells. In these cases MAC-specific neoAg was visualized at the zone of contact between the cells. Anti-neoAg Ig was found to inhibit ADCC plaque assays up to 62%; and 51Cr-release assays up to 79%. Stimulation of lymphocytes by PHA or mixed lymphocyte culture increased the expression of neoAg. In the case of PHA, increased neoAg expression was correlated with an increased incorporation of 14C-leucine into C5, C6, C7, and C8 antigens, which was detected by immunodiffusion and autoradiography.
mesh_terms: D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D001402:B-Lymphocytes / Q000276:immunology; D001666:Binding Sites, Antibody; D002462:Cell Membrane / Q000276:immunology; D002645:Chickens; D003182:Complement C5 / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology*; D000939:Epitopes; D006462:Hemolytic Plaque Technique; D006801:Humans; D007141:Immunoglobulin Fc Fragments; D007930:Leucine / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology*; D008565:Membrane Proteins / Q000378:metabolism; D011817:Rabbits
chemical_list: D003182:Complement C5; D000939:Epitopes; D007141:Immunoglobulin Fc Fragments; D008565:Membrane Proteins; D003165:Complement System Proteins; D007930:Leucine