title: Carrier-specific T cells sufficient for the expression of multiple isotypes in B cell cultures.
abstract: A modified splenic fragment assay was used to assess the role of antigen-specific helper T cells in B cell isotype expression. Limiting numbers of carrier-specific helper T cells from lines or clones were injected along with a source of B cells into lethally irradiated unprimed recipients. The incidence of lodging of the T cell lines in recipient spleens at 18 h was determined by autoradiography to be 1.5 to 4.3% of the injected cells. These T cells were necessary and sufficient for the generation of T-dependent B cell responses within splenic fragments cultured in vitro with specific antigen. A comparison of isotypic responses from splenic and Peyer's patch B cells generated with the same T cell population revealed that a high proportion of the response from Peyer's patch B cells consisted of IgA antibody exclusively (46-57%) while the percentage of such responses from splenic B cells was much lower (7-10%). Thus, the isotype pattern of the response reflected the B cell source. Experiments in which cloned hemocyanin-specific T cells provided help to T-depleted spleen cells within splenic fragments from athymic recipients indicated that a single specificity of helper T cell is both necessary and sufficient to support the generation of antibody responses consisting of multiple isotypes. Isotype-specific T cells do not appear to be required in this system.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte; D000939:Epitopes / Q000276:immunology; D006433:Hemocyanins / Q000276:immunology; D007116:Immunization, Passive; D007132:Immunoglobulin Isotypes / Q000096:biosynthesis*; D008211:Lymphocyte Cooperation; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D008819:Mice, Nude / Q000276:immunology; D010581:Peyer's Patches / Q000166:cytology / Q000276:immunology; D011828:Radiation Chimera; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000637:transplantation; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000637:transplantation
chemical_list: D000939:Epitopes; D007132:Immunoglobulin Isotypes; D006433:Hemocyanins