T-cell regulation of IgG subclass expression by mitogen-induced plasma cells: soluble factors versus the T cells.
The human IgG subclasses expressed by plasma cells generated from circulating B cells in response to soluble T-cell factors were examined by immunofluorescence using subclass-specific monoclonal antibodies. Soluble T-cell factors were induced by a mixed lymphocyte reaction, pokeweed mitogen (PWM), or phytohemagglutinin. The distribution of IgG subclasses expressed by plasma cells induced by these factors was IgG2 greater than 75%, IgG1 less than 25%, IgG3 less than 1%, and IgG4 less than 1%. On the other hand, IgG1 was dominant when B cells were cultured with T cells and PWM: IgG1 approximately 70%, IgG2 approximately 20%, IgG3 approximately 8%, and IgG4 approximately 1%. The addition of different amounts of the T-cell factors to B cells in culture did not alter the predominance of IgG2 plasma-cell differentiation. These results suggest that T cells and their soluble factors may preferentially enhance terminal differentiation of different IgG B-cell subpopulations. In contrast, the ratio of IgA1 to IgA2 plasma-cell responses was approximately 1.5 to 1 regardless of whether the B-cell precursors were induced by T-cell factors or by the T cells plus PWM.
D000328:Adult; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007074:Immunoglobulin G / Q000145:classification*; D007376:Interleukin-2 / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D010950:Plasma Cells / Q000166:cytology / Q000276:immunology*; D011043:Pokeweed Mitogens / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007376:Interleukin-2; D008070:Lipopolysaccharides; D011043:Pokeweed Mitogens