title: Activation through CD3 molecule leads a number of human T cell clones to induce IgE synthesis in vitro by B cells from allergic and nonallergic individuals.
abstract: Seventy-eight clones established from tonsillar T lymphocytes of two nonallergic children were tested under different experimental conditions for their ability to induce in vitro IgE synthesis by B cells from allergic or nonallergic donors. After 24 hr preactivation with phytohemagglutinin (PHA), 11 out of 32 CD4+ clones from the first and 17 out of 36 CD4+ clones from the second tonsil donor showed the ability to induce IgE synthesis in vitro by B cells from both allergic and nonallergic individuals, whereas none of 10 CD8+ clones nor T blasts of PHA-induced cell lines obtained from unfractionated T cell suspensions of the same tonsils had such an effect. Seven of the 11 T cell clones from the first tonsil donor active on IgE production after pre-activation with PHA also induced IgE synthesis in vitro by nonallergic and allergic B cells upon stimulation with anti-CD3 monoclonal antibody. Under the same experimental conditions, virtually all of the T cell clones able to induce IgE synthesis in vitro by target B cells showed the ability to stimulate IgG and IgM production as well. T cell clones were also established from the peripheral blood of a nonallergic donor and were tested for their ability to induce IgE synthesis in autologous B cells. After preactivation with PHA, seven out of 35 CD4+ clones induced the production of detectable amounts of both IgE and IgG in autologous B cells. The addition to the cultures of PHA-stimulated unfractionated T cells inhibited in a dose-dependent manner the IgE but not the IgG synthesis induced by an autologous helper T cell clone in autologous B cells. Taken together, these data indicate that a remarkable proportion of human T cell clones upon triggering of the CD3 molecular complex were able to provide help for the synthesis of IgE in B cells from both allergic and nonallergic individuals. The successful induction of IgE synthesis by single T cell clones was apparently related to the lack of concomitant suppressor activity to which IgE-producing cells appeared to be exquisitely sensitive.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D002999:Clone Cells; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000096:biosynthesis*; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D008213:Lymphocyte Activation; D010835:Phytohemagglutinins / Q000276:immunology*; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D010835:Phytohemagglutinins; D007073:Immunoglobulin E