title: T-T cell interactions during in vitro cytotoxic T cell responses. VI. The role of T cell-derived colony-stimulating factor in helper T cell activation.
abstract: A limiting dilution culture system has been used to analyze the role of T cell-derived colony stimulating factor (CSF) during the activation of IL 2-producing helper T lymphocytes (HTL). EL4 thymoma-derived supernatant (EL4-SN) increased about 4-fold the frequency of HTL precursors responding to metabolically active allogeneic stimulator cells. Upon biochemical separation this biological activity within the EL4-SN segregated from interleukin 2 (IL 2) and gamma interferon but was associated with or identical to CSF. Further, a comparable rise in HTL precursor frequencies was observed when semipurified interleukin 1 (IL 1) derived from the P388 D1 cell line was added to limiting dilution cultures. In contrast to IL 1, semipurified CSF failed to facilitate the activation of HTL precursors when heat-treated allogeneic spleen cells were used as stimulator cells. Because EL4-derived CSF was found to induce IL 1 production by macrophages we conclude that T cell-derived CSF amplifies, via stimulation of antigen-presenting cells the number of inducible HTL precursors. Therefore, the CSF/IL 1-dependent increase in HTL precursor frequencies reported here may reflect the differential activation threshold of HTL-precursors, most of which will not be activated by antigen per se but only in presence of additional cytokines.
mesh_terms: D000818:Animals; D003115:Colony-Stimulating Factors / Q000096:biosynthesis / Q000502:physiology*; D007375:Interleukin-1 / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D007959:Lymphocyte Culture Test, Mixed; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D013234:Stem Cells / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology / Q000276:immunology*
chemical_list: D003115:Colony-Stimulating Factors; D007375:Interleukin-1; D007376:Interleukin-2