Collagenase and prostaglandin in connective tissue destruction: cell-cell and humoral interactions.

Connective tissue destruction is a major characteristic of chornic rheumatoid arthritis (RA). This process is accompanied by local cellular and humoral inflammatory reactions. Long-term cultures of adherent synovial cells (ASC) from patients with RA produce large amounts of collagenase and prostaglandin (PGE2), two substances that play a role in the degradation of joint structures. Lvels of collagenase and PGE2 can be stimulated (up to several hundred-fold) with a soluble factor (MCF) from cultured peripheral blood mononuclear cells (MW approximately 14,000). The monocyte-macrophages alone produce MCF but can be stimulated directly with Fc fragments of immunoglobulin or concanavalin A to increase MCF production. Addition of T lymphocytes in the presence of lectin or antigen significantly enhances the production of MCF. MCF affects other biological processes in synovial cells such as the rate of collagen synthesis, cell proliferation and sensitivity to PGE2 as well as collagen itself can further modulate collagenase release by the synovial cells and function in an amplificative loop. The understanding of these interactions between cells, mediator-effector substances and connective tissue substrates may provide a basis for devising more rational approaches to therapy of the destructive lesions which characterize RA.