Effects of gammalinolenic acid on interleukin-1 beta and tumor necrosis factor-alpha secretion by stimulated human peripheral blood monocytes: studies in vitro and in vivo.

BACKGROUND: Oils enriched in gammalinolenic acid, an unsaturated fatty acid, reduce joint pain and swelling in patients with rheumatoid arthritis. The cytokines interleukin-1 beta and tumor necrosis factor-alpha appear to contribute directly to joint tissue damage in patients with rheumatoid arthritis. Agents designed to interfere with the actions of interleukin-1 beta and tumor necrosis factor-alpha are being used to treat rheumatoid arthritis. METHODS: We examined the influence of gammalinolenic acid added to cells in vitro and administered orally in vivo on interleukin-1 beta and tumor necrosis factor-alpha secretion from activated human peripheral blood monocytes. Secretion of both cytokines was reduced by gammalinolenic acid. Administration of safflower oil as a polyunsaturated fatty acid control devoid of gammalinolenic acid did not change secretion of either cytokine. CONCLUSION: Suppression of IL-beta and TNF-alpha secretion by activated cells may be one mechanism whereby gammalinolenic acid suppresses synovitis in patients with rheumatoid arthritis.