title: Lymphocyte-mediated cytotoxicity in vitro. Effect of enhancing antisera.
abstract: The ability of antisera to suppress immune responses either in vivo or in vitro is well known. A variety of lymphocyte-target cell systems have been employed to demonstrate inhibition of cell-mediated immunity by antisera in vitro, and skin, tumor, and kidney graft survival have been prolonged by passively administered antiserum in vivo. An in vitro lymphocyte-tumor cell assay system was developed for the purpose of studying the effects of enhancing antisera (in vivo) on lymphocyte-mediated cytotoxicity in vitro. The characteristics of this system with respect to route of immunization, time of harvest of immune cells, lymphocyte:tumor cell ratio, and effect of nonimmune or nonspecifically immune lymphoid cells are presented. Sera capable of enhancement in vivo were tested in this system and shown to inhibit cell-mediated immunity in vitro. Further, in both instances the immunosuppressive effect is mediated by antigen-antibody complexes and not by free antibody alone. Experiments were also carried out to determine the site of action of these suppressive antigen-antibody complexes. Presensitized lymphocytes were exposed to antigen-antibody complexes, washed, and then allowed to interact with fresh tumor cells (not antibody treated). Lymphocytes treated in this manner are incapable of exhibiting cell-mediated immunity in vitro. This evidence supports the concept that the antigen-antibody complexes have a direct immunosuppressive effect on the lymphocyte.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D002452:Cell Count; D046508:Culture Techniques; D003601:Cytotoxicity Tests, Immunologic; D004195:Disease Models, Animal; D007106:Immune Sera / Q000494:pharmacology*; D007111:Immunity, Cellular; D007114:Immunization; D007165:Immunosuppression Therapy; D007700:Kinetics; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000276:immunology*
chemical_list: D000936:Antigen-Antibody Complex; D007106:Immune Sera