Tumor cells stimulate interleukin 1 (IL-1) production from enriched large granular lymphocytes

When enriched large granular lymphocytes (LGLs) were activated by K562 cells substantial amounts of interleukin 1 (IL-1) could be detected in the supernatants as measured by the mouse thymocyte assay. IL-1 could also be produced by LGLs treated with other tumor cells according to their ability to be lysed by LGLs. Therefore PLC/PRF/5 hepatoma cells which were moderately sensitive to LGL attack stimulated moderate amounts of IL-1 from the LGLs. Yac-1 cells and human fibroblasts which are resistant to LGL cytolysis did not activate LGLs to produce significant amounts of IL-1. IL-1 was shown to be produced by LGLs and not by the stimulatory tumor cells. Interferon-alpha (IFN), which reduced the susceptibility of target cells to be lysed by LGLs, also inhibited their ability to stimulate IL-1 production from LGLs. The IL-1 stimulatory effect of tumor cells on LGLs could not be attributed to Mycoplasma or endotoxin contamination. It is suggested that LGLs release IL-1 when they encounter susceptible cells and that release of this cytokine is important in the subsequent lysis of target cells.