Chronic immune synovitis in rabbits. II. Modulation by anti-inflammatory and anti-rheumatic agents.

Synovitis was induced in rabbits sensitized to bovine serum albumin (BSA) by a modification of the method of Dumonde and Glynn. Agents were administered starting on the day of initial BSA joint challenge and every weekday (14-17 doses) for 17 to 21 day periods. Synovial tissues were then excised and evaluated either (1) histologically for inflammatory cell infiltration, or (2) both histologically and for total IgG, anti-BSA, and beta-glucuronidase levels in homogenates of portions of the same tissues. By the intraperitoneal and oral routes, methylprednisolone (1 mg/kg/day), azathioprine (25-40 mg/kg/day) and cyclophosphamide (10 mg/kg/day) produced significantly decreases of 40-100% in some or all of the parameters measured. Non-steroidal anti-inflammatory drugs, including phenylbutazone, ibuprofen and acetylsalicylic acid at oral doses of 75 or 100 mg/kg/day, were ineffective as were colchicine at 1 mg/kg/day and indomethacin at 5 mg/kg/day. Thus, as we have measured it, this model of rheumatoid arthritis is not affected by those agents considered to be of limited effectiveness in this chronic disease, but is ameliorated by corticoids and some slow acting agents.