Stimulation of rheumatoid synovial cell collagenase and prostaglandin production by partially purified lymphocyte-activating factor (interleukin 1).

Human macrophages produce in culture a factor termed mononuclear cell factor (MCF) that increases the production of collagenase and prostaglandins by isolated adherent rheumatoid synovial cells. A factor with similar biologic activity is also produced by the murine macrophage cell line P388D1. By using a sequential purification scheme involving ammonium sulfate fractionation; chromatography on DEAE-cellulose, Sephacryl S-200, and phenyl-Sepharose; and discontinuous polyacrylamide gel electrophoresis, the P388D1 cell-derived, synovial cell-stimulating factor was copurified with the lymphocyte-activating factor [LAF; interleukin 1 (IL 1)]. The specific activity of the partially purified LAF (IL 1) was approximately 15,000-fold higher than that of the LAF (IL 1) in the original P388D1 cell culture supernatant. On the basis of (i) the copurification of the P388D1 cell-derived LAF (IL 1) and synovial cell-stimulating factors; (ii) the similarity in cell of origin, molecular weight, and phenylglyoxal sensitivity of human MCF and murine LAF (IL 1); and (iii) the presence of LAF (IL 1) activity in preparations of partially purified human MCF, we have postulated that LAF (IL 1) may have effects on cell targets that are nonlymphoid in nature and also that human MCF may be similar to, or identical with human LAF (IL 1). The results of these studies have raised the possibility that LAF (IL 1) may play a role in macrophage-mediated activation of synovial cells and lymphocytes which are involved in the inflammatory responses associated with rheumatoid arthritis.