Differences in the production of arachidonic acid metabolites between healthy and rheumatic synovial fibroblasts in vitro. A preliminary study.

Production of various arachidonic acid metabolites from both endogenous and exogenous substrate was measured using cultures of synovial fibroblasts from healthy and rheumatic synovia. At first, the rheumatic cells showed retarded growth and an altered histological picture. Rheumatic cells produced more 6-keto-PGF1 alpha, the main metabolite of prostacyclin, and prostaglandin E2 than did normal cells, which synthesized more thromboxane B2. Later on these differences diminished or disappeared, except regarding 6-keto-PGF1 alpha. When fairly high concentrations of exogenous arachidonic acid were used, for 2-hour incubation of the cells, the production of identified metabolites, 6-keto-PGF1 alpha, PGF2 alpha, PGE2, PGD2, PGA + PGB and thromboxane B2, was slightly less in rheumatic cells. In general, the main metabolite formed was 6-keto-PGF1 alpha. Some kind of feedback mechanism between prostaglandins and cyclic nucleotides is suggested.