An IgM antibody is a potent immunosuppressive agent that inhibits B cell proliferation.
The results of this study demonstrate that the culture supernatant of lipopolysaccharide (LPS)-stimulated murine spleen cells is able to inhibit the growth of freshly isolated B lymphocytes. The inhibition is specific for B cells because the suppression of the LPS, Fc-fragment of human IgG, dextran sulfate, and anti-mu induced proliferation of B, but not the Concanavalin A response of T lymphocytes could be shown. The cells producing the inhibitor do not adhere to plastic, and are Thy-1 negative but surface Ig positive, i.e. they are B lymphocytes. The regulatory substance is heat resistant, sensitive to trypsin treatment, and has a high molecular weight of approximately 1000 kDa. Moreover, it is specifically adsorbed on, and can be eluted from, anti-mu and anti-Ig immunoaffinity columns. Thus, it seems to be an IgM antibody. Non-specific effects were excluded by the ineffectiveness of poly- and monoclonal IgM proteins. IgM-IgG complexes were also excluded. Thus, these results suggest the existence of a novel IgM antibody mediated control mechanism regulating B cell growth during polyclonal activation.
Alonso
M E
ME
Department of Immunology, Lóránd Eötvös University, Göd, Hungary.
Uher
F
F
Gergely
J
J
D000818:Animals; D000943:Antigens, Differentiation / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D007108:Immune Tolerance; D007075:Immunoglobulin M / Q000276:immunology*; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008811:Mice, Inbred DBA; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D011961:Receptors, Fc / Q000032:analysis; D017452:Receptors, IgG
D000943:Antigens, Differentiation; D007075:Immunoglobulin M; D008070:Lipopolysaccharides; D011947:Receptors, Antigen, B-Cell; D011961:Receptors, Fc; D017452:Receptors, IgG