AIMTo investigate the effects of the recombina nt human endostatin on adjuvant arthritis (AA) in rats and its mechanisms. METHODSThe model of rat AA was induced by injection of intradermal CFA. ConA and LPS induce d splencytes proliferation was examined by MTT asssy and the activities of inter leukin-1 (IL-1) and IL-2 were measured by the method of thymocytes prolifera tion. Synoviocytes were dispersed with incubation of collagenase and trypsin, an d IL-1, TNF production of synoviocytes was estimated with radio-immunity assay . RESULTSThe secondary inflammation of AA rats appeared on the 1 0th day after injection of CFA. The therapeutic administration of endostatin (0 1, 0 5, 2 5 mg·kg -1 ·d -1 , sc, ×7 d) was given at that time(d 10). It was found that endostatin significantly inhibited the secondary paw swel ling. The increased ConA-induced splenic lymphocyte proliferation reaction and the activated IL-1 and IL-2 activity of AA rats was reversed by the treatment with endostatin. Meanwhile,IL-1 produced by PMΦ was increased. Endostatin inh ibited IL-1 production from PMФ and IL-1 and reduced TNF level of Synoviocyte s in AA rats. CONCLUSIONThe recombinant human endostatin has the rapeutical effect on AA rats, its mechanisms is related to its immunoregulative function.