Participation of Monocyte-Macrophages and Lymphocytes in the Production of a Factor that Stimulates Collagenase and

man peripheral blood produce a soluble factor (MCF) that stimulates collagenase and prostaglandin E2 (PGE2) release by cultured rheumatoid synovial cells up to several hundredfold. These target rheumatoid synovial cells lack conventional macrophage markers. To deter-mine which mononuclear cells are the source of MCF, purified populations of monocyte-macrophages, thy-mus-derived (T) lymphocytes, and bone-marrow-derived (B) lymphocytes were prepared. The monocyte-macrophages alone produced levels of MCF that were proportional to cell density but unaffected by phytohemagglutinin or pokeweed mitogen. No detect-able collagenase activity was produced by the cultured monocyte-macrophages or lymphocytes. Purified T lymphocytes produced levels of MCF-1-3 % those of purified monocyte-macrophages in the presence or absence of the above lectins. Purified T lymphocytes modulated the production of MCF by the monocyte-macrophages, however, in a manner dependent upon relative cell densities and the presence of lectins. For example, at optimal ratios of T lymphocytes: monocyte-macrophages, MCF production was mark-edly stimulated by pokeweed mitogen. Thus, inter-actions of T lymphocytes and monocyte-macrophages could be important in determining levels of MCF, which regulate collagenase and PGE2 production by target synovial cells in inflammatory arthritis. This is publication No. 785 of the Robert W. Lovet