Restriction mechanisms of B cell regulation by a physiological IgG-anti-immunoglobulin autoantibody.
Immunization of LEW rats with strongly histoincompatible BN blood cells induces, in addition to anti-donor antibody, a broadly reactive IgG autoantibody which binds to IgG and IgM molecules (IgG anti-Ig). Minute amounts of affinity purified IgG anti-Ig (0.2 pg/10(6) cells) suppress the antibody production in vitro of antigen receptor (AgR)-stimulated B cells derived from rats of the same strain. The suppressive antibody is also active in the whole serum IgG fraction. Importantly, anti-Ig-induced suppression is governed by restriction mechanisms: only AgR-occupied B cells are affected, the suppression is cell cycle dependent, and maximum suppression is obtained at an optimum IgG concentration. Treatment of rats in vivo with 0.8 mg Ig-anti-Ig (whole IgG fraction) along with allogeneic cells resulted in nearly complete suppression of the anti-donor antibody response. Possible mechanisms of B cell suppression by IgG anti-Ig are crosslinking of AgR with FcR, or cocapping of the two receptors with sterical interaction as a consequence of their separate occupation. Both alternatives lead to the release of an inactivating signal.
Terness
P
P
Department of Transplantation Immunology, University of Heidelberg, Germany.
Süsal
C
C
Opelz
G
G
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology*; D001323:Autoantibodies / Q000502:physiology*; D001402:B-Lymphocytes / Q000276:immunology*; D007108:Immune Tolerance; D007074:Immunoglobulin G / Q000276:immunology*
D000888:Antibodies, Anti-Idiotypic; D001323:Autoantibodies; D007074:Immunoglobulin G