Antireceptor antiserum causes specific inhibition of reactivity to rat histocompatibility antigens.

The antigen receptor of lymphocytes destined to form antibody appears to have the characteristics of the immunoglobulin produced. Antibody directed against the combining region of this immunoglobulin should interact with the combining region of the cell receptor for the antigen. Purified Lewis rat alloantibody prepared against Brown Norway (BN) rat histocompatibility antigens was used to immunize L x BN F(1) hybrids. The resultant antiserum has anti-receptor activity because (i) it yields precipitin lines in gel diffusion when reacted against the immunizing alloantibody; (ii) it inhibits the hemagglutinin antibody response of Lewis rats to BN histocompatibility antigens; and (iii) it inhibits the local graft-versus-host response of Lewis lymphoid cells against BN antigens. This suggests that antireceptor antibody may inhibit cell-mediated responses as well as antibody responses to histocompatibility antigens and may play a role in the regulation of immune responses to such antigens.