title: Human T cell clones can induce in vitro IgE synthesis in normal B cells regardless of alloantigen recognition or specificity for peculiar antigens.
abstract: A total number of 119 (98 CD 4+ and 21 CD 8+) T cell clones were established from tonsil and peripheral blood of three nonallergic individuals and examined for their ability to induce in vitro IgE synthesis in normal B cells. Following preactivation for 24 h with phytohemagglutinin, 34 clones (33 CD 4+ and 1 CD 8+) induced normal B cells to synthesize remarkable amounts of IgE in vitro. In contrast, equal numbers of T blasts of phytohemagglutinin-induced T cell lines obtained from unfractionated T lymphocyte suspensions of the same donors did not show such an effect. The in vitro IgE synthesis evoked by T cell clones was detectable between day 6 and 9 and peaked on day 12. Most clones maintained their ability to stimulate in vitro IgE synthesis in repeated assays over a 3-month period. The induction of IgE synthesis by cloned T cells did not reflect alloantigen recognition on target B cells, since T cell clones induced IgE synthesis in B cells from all randomly selected donors tested, including autologous B cells. Preincubation for 24 h with optimal stimulatory concentrations of anti-CD 3 (OKT 3) monoclonal antibody or its addition through the entire culture period also enabled T cell clones to stimulate de novo IgE synthesis in vitro in normal B cells. Virtually all the T cell clones active on IgE synthesis induced the in vitro production of remarkable amounts of IgM and IgG as well. These data indicate that several human T cell clones can induce normal B cells to synthesize immunoglobulin of different classes, including IgE, regardless of alloantigen recognition on target B cells or specificity for peculiar antigens. The activity of these clones was apparently mediated by triggering of the monomorphic molecular complex CD 3, immediately before or during the incubation of T cell clones with the target B cells.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D002999:Clone Cells; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis*; D007132:Immunoglobulin Isotypes / Q000096:biosynthesis; D007519:Isoantigens / Q000276:immunology*; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D007132:Immunoglobulin Isotypes; D007519:Isoantigens; D007073:Immunoglobulin E