Activated B cells express receptors for, and proliferate in response to, pure interleukin 2.
In this study we investigated whether interleukin 2 (IL-2) acts on B cell proliferation and whether activated B cells express IL-2 receptors. First, the functional activity of immunoaffinity-purified or recombinant human IL-2 was studied in a B blast assay using positively selected murine surface Ig-positive cells that had been activated by lipopolysaccharide (LPS) plus anti-Ig antibodies (anti-Ig). In this assay, T cells were not detected by fluorescence-activated cell sorter analysis. It was found that both IL-2 preparations led to optimal B cell proliferation compared with supernatants obtained from murine or human spleen cells or murine cloned T helper cells. Second, we observed that the IL-2 requirement in this assay was about the same as in a proliferation assay using lectin-activated polyclonal murine Lyt-2-positive T cells. Third, analysis of the binding of radiolabeled immunoaffinity-purified IL-2 to B cells indicated that LPS plus anti-Ig-activated B cells expressed a mean of 3,500 IL-2 receptors per cell with an apparent dissociation constant of 150 pM. However, neither nonactivated B cells nor B cells activated by LPS alone exhibited significant specific IL-2 binding. The functional and the receptor data are consistent with the conclusion that IL-2 is a growth factor not only for T cells but also for B cells.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D006133:Growth Substances / Q000096:biosynthesis; D007376:Interleukin-2 / Q000378:metabolism* / Q000502:physiology; D015847:Interleukin-4; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D011971:Receptors, Immunologic / Q000032:analysis*; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D006133:Growth Substances; D007376:Interleukin-2; D008070:Lipopolysaccharides; D008222:Lymphokines; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D015847:Interleukin-4