Synergy between interleukin-2 and a second factor in the long-term growth of human T cells.
It has recently been shown that factors in addition to interleukin-2 (IL-2) are required for the proliferation or differentiation of at least some murine T-cell lines. We have previously shown that conditioned medium from human mononuclear cells stimulated with phorbol ester and staphylococcal enterotoxin A is superior to commercial sources of IL-2 for the long-term growth of human T cells. We have identified in these supernatants a non-IL-2 factor (synergistic factor, SF) which synergizes with JURKAT IL-2 in the long-term growth of human T cells. [3H]TdR incorporation by IL-2-dependent human T cells after growth in IL-2 or SF alone for 14 days was slight, but significant. By contrast, growth in a combination of SF and IL-2 for 14 days stimulated [3H]TdR incorporation 10-20-fold higher, generally equal to the high incorporation measured when cells were grown in the presence of the conditioned medium from which SF was obtained. In a standard 2-day IL-2 assay, there was no correlation between activity and long-term growth-promoting ability. These results suggest that the 14-day assay better discerns the growth-promoting activity of various factors or combinations of factors. The mechanism of this interaction between SF and IL-2 remains to be elucidated. It is clear, however, that T-cell growth factor activity, when assessed by the long-term growth of human T cells, is not due to interleukin-2 alone.
D000954:Antigens, Surface / Q000276:immunology; D002478:Cells, Cultured; D004357:Drug Synergism; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology*; D008938:Mitosis / Q000187:drug effects; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors
D000954:Antigens, Surface; D006133:Growth Substances; D007376:Interleukin-2; D013936:Thymidine