title: Interleukin 2 induces both, growth and maturation of lectin reactive Lyt-2+ but not Lyt-2-precursor cells and regulates the cytolytic potential of effector cells.
abstract: This study investigated the requirements for lymphokines derived by recombinant (rec.) DNA technology for the induction of growth and maturation in highly purified lectin reactive T cell subsets. Nylon purified C57BL/6 lymph node T cells were treated with monoclonal anti-Lyt-2.2 or anti-L3T4 antibodies and fluorescence labeled (FITC) anti-immunoglobulin antibodies and were positively selected into Lyt-2+ (L3T4-) and Lyt-2- (L3T4+) lymphocyte subsets using a fluorescence-activated cell sorter. Sorted T lymphocytes, which were devoid of accessory cells were incubated either in bulk culture (2 X 10(2) - 3 X 10(4) cells/microculture) or under limiting dilution conditions (2.5-1,000 cells/well) with lectin (Concanavalin A, Leukoagglutinin) and rec. human Interleukin 2 (rec. hIL-2) and/or rec. mouse Interferon gamma (rec. mIFN-gamma). The data show that Lyt-2+ lymphocytes respond to lectin and rec. hIL-2 with growth and development of cytolytic activity in the absence of other exogenous factor(s) or accessory cells. The presence of monoclonal antibodies to the Interleukin 2 receptor during the sensitization phase ablated the induction of Con A reactive precursor cells of cytolytic lymphocytes (CTL-P) by either rec. hIL-2 or conventional IL-2 containing lymphokine sources, indicating the essential role of IL-2 during activation of Lyt-2+ T lymphocytes. In contrast, Lyt-2- lymphocytes could not be induced by lectin and rec. hIL-2 alone for proliferation and always required the presence of accessory cells for significant growth. Exogenous rec. m IFN gamma was unable to induce growth and cytolytic activity in Con A reactive Lyt-2+ cells and did not significantly effect their response to rec. hIL-2. Limiting dilution experiments revealed that 10-16% of the Lyt-2+ lymphocytes responded to Con A and rec. hIL-2 with growth (GTL-P). The frequencies of CTL-P, determined under similar conditions, were always lower compared to GTL-P. However the results suggest that the differences observed between both precursor populations is due to differential sensitivity of the detection system rather than to the recruitment of distinct T cell subsets. Furthermore, it was shown that at least 50% of lectin reactive CTL-P were induced by rec. hIL-2 to secrete IFN-gamma under optimal conditions. The finding that some of the conventional lymphokine sources were superior to rec. hIL-2 in the induction of growth and cytolytic activity suggests the existence of mediators distinct from IL-2 that regulate the expansion of CTL-P.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000373:Agglutinins / Q000494:pharmacology; D000818:Animals; D000950:Antigens, Ly / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects; D002469:Cell Separation; D003208:Concanavalin A / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D005434:Flow Cytometry; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis / Q000494:pharmacology*; D007518:Isoantibodies / Q000276:immunology; D007962:Leukocytes; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011506:Proteins; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism
chemical_list: D000373:Agglutinins; D000950:Antigens, Ly; D007376:Interleukin-2; D007518:Isoantibodies; C029805:Lyt antibodies; D011506:Proteins; D011994:Recombinant Proteins; C100155:leukoagglutinins, leukocytes; D003208:Concanavalin A; D007371:Interferon-gamma