title: IL 2 production by mitogen-stimulated T cell subsets: helper-precursors are predominantly Lyt-2-.
abstract: Although there is strong evidence that IL 2 can be secreted by at least some cells in both the Lyt-2- and Lyt-2+ T cell subsets, it is unclear whether lymphokine-secreting cells are present in equal frequencies in each population. We addressed this question by using a T cell mitogen, concanavalin A (Con A), that activates a large proportion of the cells of both subsets, as tested by their ability to grow in the presence of added conditioned medium. We found that, although Con A-responsive precursors of proliferating cells are at least as frequent in the Lyt-2+ set as in the Lyt-2- set, the frequency of Con A-responsive precursors of IL 2-secreting cells is much higher in the Lyt-2- population. Expressed as precursors per cell, lymphokine-secreting helpers are 17-fold more frequent in the Lyt-2- population. After adjusting for relative cell recoveries and for contamination, the data suggest that at least 97% (and more likely 99%) of the precursors for Con A-responsive IL 2-producing cells are in the Lyt-2- set. Thus, although the correlation between Lyt-2 surface antigen and helper function may not be absolute, our data support the idea that Lyt-2 does mark a functional distinction among T cells independent of antigen specificity.
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000145:classification / Q000276:immunology; D002469:Cell Separation; D003208:Concanavalin A / Q000494:pharmacology*; D000939:Epitopes / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D013234:Stem Cells / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D000950:Antigens, Ly; D000939:Epitopes; D007376:Interleukin-2; D003208:Concanavalin A