title: Signal requirement for interleukin-1-dependent interleukin 2 production by a human leukemia-derived HSB.2 subclone.
abstract: We have previously established subclones from human leukemia-derived HSB.2 cell line that produced high levels of interleukin (IL) 2 when stimulated with phytohemagglutinin (PHA) and IL-1. Herein, we investigated the signal requirement for IL-2 production, particularly concerning the role of IL-1 in this system. PHA but not IL-1 rendered marked protein kinase C (PKC) activation and IL-2 production induced by PHA plus IL-1 was totally abrogated by a potent PKC inhibitor, H-7. Concomitantly, PHA alone caused marked Ca2+ influx, whereas IL-1 neither induced Ca2+ influx nor augmented PHA-induced Ca2+ influx. As expected, a signal delivered by PHA could be substituted by phorbol 12-myristate 13-acetate (PMA) and ionomycin while IL-1 was still indispensable, indicating that at least three signals, i.e., those delivered by IL-1 as well as PKC activation and Ca2+ influx were required for optimal IL-2 production. Kinetic study indicated that while PMA and ionomycin should be added at the initiation of culture, delayed addition of IL-1 up to 4 hr later induced even higher levels of IL-2 production, demonstrating the requirement for IL-1 after PKC activation and Ca2+ influx. In this system, it was revealed that IL-1 was not involved in PKC activation, Ca2+ influx, and breakdown of phosphatidylinositols. Whereas PMA, ionomycin, and IL-1 stimulated high levels of IL-2 production, those combinations of signals did not induce breakdown of phosphatidylinositols. It should be noted that IL-2 production induced by these three signals seemed to bypass hydrolysis of phosphatidylinositols in contrast to PHA plus IL-1 stimulation that was accompanied with a marked breakdown of phosphatidylinositols.
mesh_terms: D002118:Calcium / Q000378:metabolism; D004789:Enzyme Activation; D004987:Ethers / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology / Q000502:physiology*; D007376:Interleukin-2 / Q000096:biosynthesis*; D015759:Ionomycin; D007938:Leukemia / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects*; D010716:Phosphatidylinositols / Q000378:metabolism; D010835:Phytohemagglutinins / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology*
chemical_list: D004987:Ethers; D007375:Interleukin-1; D007376:Interleukin-2; D010716:Phosphatidylinositols; D010835:Phytohemagglutinins; D015759:Ionomycin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium