title: Downregulation of L3T4+ cytotoxic T lymphocytes by interleukin-2.
abstract: Proliferation of activated cytotoxic T lymphocytes (CTLs) that recognize foreign histocompatibility antigens is induced by interleukin-2, a potent immunoregulatory molecule originally described as T cell growth factor. Interleukin-2 (IL-2) is widely used to isolate and induce clonal expansion of CTLs for functional studies in vitro and in vivo. However, in studies with CTLs specific for class I and class II histocompatibility antigens, IL-2 rapidly downregulated the lytic activity of some class II-specific CTLs in a time- and dose-dependent manner. Lytic activity of L3T4+ CTLs specific for the murine class II antigen I-Ek was repeatedly up- and downregulated in vitro by alternate exposure to specific (alloantigen) and nonspecific (recombinant IL-2) signals, respectively. These results demonstrate that some CTLs modulate their functional property (cytolysis) while undergoing IL-2-driven cell proliferation without loss of antigen specificity or ability to revert to a lytic phenotype.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics; D002460:Cell Line; D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D006183:H-2 Antigens / Q000276:immunology; D007376:Interleukin-2 / Q000502:physiology*; D007519:Isoantigens / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D010641:Phenotype; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000939:Epitopes; D006183:H-2 Antigens; D007376:Interleukin-2; D007519:Isoantigens