Various extracts of the Chinese herbal medicine Tripterygium wilfordii Hook. f.（TWHF）have been reported to be therapeutically effective for rheumatoid arthritis（RA）in China, but their action mechanism has not been understood well. Although triptolide, a diterpenoid triepoxide from TWHF, suppresses the inflammatory cytokine production in vitro, the influence of triptolide on immune system is not fully understood well. The present study, therefore, was designed to examine the effects of triptolide on cytokines production in vitro and in vivo by using adjuvant arthritic rats.
　　The first part of these experiments was designed to examine the effects of triptolide on arthritic rats. Adjuvant arthritis was induced in male Wistar rats by a single subcutaneous injection of 0.1 mL complete Freund's adjuvant into the hind paw. Arthritic rats were injected intraperitoneally with various doses of triptlide once a day for 1 week, starting one week after adjuvant injection. The minimum concentration of tiptolide, which caused significant suppression of paw swelling, was 0.3 mg/kg. The second part of these experiments was carried out to measure the ability of cytokine production by splenocytes from the arthritis rats which were treated with triptolide. Triptolide caused suppression of IL-1β and IL-6 production in splenocytes which was activated by concanavalin A.
　　These data suggest that the therapeutic effects of TWHF in RA are in part due to the novel chondroprotective effects of triptolide via suppression of IL-1β and IL-6 production.