Protective effect of D8 (100 µg), methotrexate (MTX) (0·25 mg/kg) and MTX combined with D8100 µg, compared with phosphate-buffered saline (PBS) controls, on the arthritic score in adjuvant-induced arthritis (AIA) (± standard error, percentage). Both D8100 µg and MTX treatment caused a statistically significant reduction of the arthritis score (P < 0·05) compared with PBS as of day 13. By the end of the experiment on day 24, a statistically significant reduction in the arthritis score was observed in rats treated with MTX + D8100 µg compared with rats treated with MTX alone. A significant difference was also observed on day 24 in the mean ankle width between these groups (not shown).