title: Augmentation of in vitro humoral immune responses in the mouse by an antibody to IgD.
abstract: Heterologous anti-delta-chain antibodies have an adjuvant effect on specific in vivo humoral immune responses to simultaneously, or subsequently, injected antigens in the rat and rhesus monkey. We have used a hybridoma-secreted antibody that binds murine delta-chain of the allotype (4.22aM delta a) to study this phenomenon in the mouse and to investigate the mechanism of this effect. Injection of 4.22aM delta a into BALB/c mice removes almost all surface IgD (sIgD) from splenic B lymphocites. sIgD does not reappear until the serum level of 4.22aM delta a decreased 5-7 d after injection. 4.22aM delta a fails to induce detectable proliferation or to raise total serum Ig levels substantially above control values. However, 4.22aM dalta a injected 24 h before antigen elicits an approximately twofold enhancement of serum IgM and a 3- to 10-fold enhancement of serum IgG anti-trintriphenyl (TNP) antibodies in response to immunization with optimal doses of TNP-Ficoll or TNP-sheep red blood cells (TNP-SRBC). 4.22aM delta a injected 1 wk before or 3 d after TNP-SRBC, however, has no effect on IgG anti-TNP levels. The adjuvant effect of anti-delta-chain antibody was markedly decreased when suboptimal antigen doses were used. Furthermore, even in the case of TNP-Ficoll, a relatively T-independent antigen, the ability of 4.22aM dalta a to enhance the anti-TNP antibody response was T cell dependent. Our data suggest that the binding of anti-delta-chain antibody to cell sIgD may partially activate B lymphocytes and make them more capable of differentiating into antibody-secreting cells when stimulated by antigen-specific T cell help.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D007072:Immunoglobulin D; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D007156:Immunologic Memory; D008211:Lymphocyte Cooperation; D051379:Mice; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007072:Immunoglobulin D; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell