Modulation of cell proliferation by human recombinant interleukin-1 and immune interferon.

The growth-modulating effects of recombinant alpha- and beta-forms of human interleukin-1 (IL-1) and interferon-gamma (IFN-gamma) were examined with several human cell lines. Exposure to combinations of IL-1 and IFN-gamma resulted in three categories of cell response. The first was cell lines in which IL-1 stimulated growth and offset the growth inhibitory effects of IFN-gamma. These lines included the lung carcinoma CALU-1 and the colon carcinoma SW-48. The second was some of the cell lines that were refractory to IL-1 and that were inhibited by IFN-gamma alone. These included the cervical carcinoma HeLa, the transformed milk line HBL-100, and the myelogenous leukemia K562. The third group consisted of cells in which growth inhibition by IL-1 and IFN-gamma was additive. These included the mammary carcinomas MCF-7 and MDA-MB-415. The exception to this latter group was ME-180 in which significant additive inhibitory effects could not be demonstrated. IL-1 alone primarily induced a cytostatic effect in growth-inhibited cell lines. The cytolytic effect induced by IFN-gamma was increased in the presence of IL-1. The data support the conclusion that the effects on growth of IL-1 and IFN-gamma are mediated by different mechanisms.