title: Mode of action of antigen-specific T-cell helper factors secreted by a T-cell line and clones.
abstract: Antigen-specific T-cell helper factors were secreted from a (T,G)-A--L specific T-cell line and clones. The factors were released upon antigenic stimulation and could be induced by a low or a high dose of antigen. The factors secreted upon low-dose stimulation possessed the antigenic specificity of the secreting cells, while the high dose-induced factors had a broader antigenic specificity and could react with the closely related polypeptide (Phe,G)-A--L, even when the cells were restricted to (T,G)-A--L. Both the low dose- as well as the high dose-induced factors could not trigger antibody production in the presence of a non-relevant antigen, and did not collaborate with B cells immunized with a non-related antigen for the production of antibodies. The helper factors, like their secreting cells, were H-2-restricted in the collaboration with B cells. In contrast to the helper cells, however, they did not require accessory cells for triggering the B cells in the process of antibody production. Some preparations of helper factors were found to be inactive. The helper activity could be restored by IL-2. Thus, IL-2 is an additional essential factor required for the antigen-specific collaboration of B cells and T-cell helper factors.
mesh_terms: D000818:Animals; D002460:Cell Line; D002999:Clone Cells / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000276:immunology*; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D010455:Peptides / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism
chemical_list: D000939:Epitopes; D008222:Lymphokines; D010455:Peptides; C021759:(T,G)-A-L