title: T cell-dependent hapten-specific and polyclonal B cell responses require release of interleukin 5.
abstract: CD4+ T cells in the mouse have recently been subdivided into two major subpopulations which differ in their functional activities and in the lymphokines they produce. Although cloned T cells lines representative of both sets will activate B cells in polyclonal responses, only the subset producing interleukin 4 (IL-4) will activate antigen-specific B cells in linked recognition assays. This suggested that IL-4 was essential for such responses. In the present experiments, the requirements were compared for B cell activation in specific as opposed to polyclonal antibody responses by T cell clones of the helper (IL-4 producing) subset. It was found that specific responses involve primarily small B cells, whereas polyclonal responses activate exclusively the large B cells. Second, polyclonal B cell responses can proceed in the absence of T:B contact, whereas specific responses require physical interaction of the two cells. Third, it was found that interleukin 5 (IL-5, formerly known as T cell replacing factor/B cell growth factor II) is essential for these polyclonal responses by inhibition of such responses with monoclonal anti-IL-5 antibody. Anti-IL-5 also inhibits specific antibody responses involving direct T:B interaction. Thus, IL-5 is clearly a critical mediator of differentiation to immunoglobulin secretion of activated B cells, whether such B cells are obtained as large B cells from freshly isolated spleen cells or are initially activated in an IL-4-dependent fashion by cognate interaction by a helper T cell clone.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002474:Cell-Free System; D002999:Clone Cells / Q000276:immunology; D000939:Epitopes / Q000276:immunology; D006241:Haptens / Q000276:immunology*; D006462:Hemolytic Plaque Technique; D007136:Immunoglobulins / Q000096:biosynthesis; D015848:Interleukin-5; D007378:Interleukins / Q000378:metabolism* / Q000502:physiology; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D051379:Mice; D008810:Mice, Inbred C57BL; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism
chemical_list: D000939:Epitopes; D006241:Haptens; D007136:Immunoglobulins; D015848:Interleukin-5; D007378:Interleukins