title: Limiting dilution analysis of IL-2 production: studies of age, genotype, and regulatory interactions.
abstract: We have previously described a limiting dilution method for estimating both the frequency of mouse T helper cells that can respond to alloantigens by producing Interleukin-2 (IL-2) and the amount of IL-2 produced by each responding cell (together with its progeny). At these very low cell concentrations, the amount of IL-2 produced per cell is remarkably higher (30-300 X) than the amounts generated under conventional, high density, culture conditions. We show here that cells cultured at intermediate densities "regulate" the amounts of IL-2 produced, so that the IL-2 concentration becomes independent of helper cell dose. The much higher level of IL-2 produced at very low concentrations therefore probably represents the loss, by dilution, of a regulatory cell that is less frequent than the IL-2 producing cells themselves. We show also how limiting dilution methods can be applied to KLH-responsive IL-2 secreting cells, and to questions about the effects of genotype and age on IL-2 production (Key words: Interleukin-2, helper T cells, aging, suppressor cells).
mesh_terms: D000367:Age Factors; D000818:Animals; D002452:Cell Count; D002478:Cells, Cultured; D005838:Genotype; D006433:Hemocyanins / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis*; D007519:Isoantigens / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D007376:Interleukin-2; D007519:Isoantigens; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin