title: Cytotoxic versus immunoblocking effects of specific alloantibodies: effects of IgM, IgG, and IgG2 on rat kidney allograft survival.
abstract: Passively introduced IgM alloantibodies of antidonor specificity regularly led to decreased kidney allograft survival times, whereas IgG alloantibodies from the same hyperimmune sera had a specific immunoblocking effect that promoted prolonged allograft survival. These strikingly opposite effects as a function of antibody isotype occurred across both strong H-1 (Ag-B) and moderate non-H-1 histocompatibility barriers. However, IgM and IgG directed against non-H-1 specificities were far more effective, respectively, in either curtailing or prolonging renal allograft survival. In the Fischer to Lewis strain combination, this was reflected in a 4-fold diminution in median survival time of IgM-treated recipients from 115 to 31 days, in contrast to indefinitely prolonged survival of IgG-treated recipients (greater than 350 days). Purified IgG2 alloantibodies proved as effective as the whole IgG fraction in passively promoting long-term renal allograft survival across a strong H-1 barrier. Conflicting data from other sources is evaluated. Possible mechanisms of specific immunoregulation are briefly discussed in relation to antibody properties of specificity, idiotype, class-subclass, and avidity-affinity.
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D003601:Cytotoxicity Tests, Immunologic; D006085:Graft Survival; D007112:Immunity, Maternally-Acquired; D007126:Immunoglobulin Allotypes; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007518:Isoantibodies; D016030:Kidney Transplantation; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew
chemical_list: D007126:Immunoglobulin Allotypes; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007518:Isoantibodies