The effects of tumor necrosis factor on the production of interleukin-1 by macrophages.

We investigated the effect of tumor necrosis factor (TNF) on interleukin-1 (IL-1) production by mouse macrophages. At high doses of TNF, macrophages produced no IL-1 (as judged in the LAF assay) even when exposed to bacterial lipopolysaccharide (LPS), an excellent inducer of IL-1 production. In lower (picogram/ml) doses, TNF caused macrophages to make factors which showed modest activity in the LAF assay and that activity could be blocked by antibody to IL-1. TNF induces in low doses also the production of a factor(s) which synergizes with IL-1 in the LAF assay.