Some further effects of prednisolone and triamcinolone hexacetonide on experimental arthritis in rabbits.

Prolonged treatment of rabbits with an established bilaterally symmetrical experimental arthritis with prednisolone (0.5 mg/kg day) reduced both the swelling and the histopathological changes in the arthritic joints whereas short-term treatment suppressed only the swelling. Such prolonged treatment also suppressed both the humoral and cell-mediated immune responses measured systemically in these animals and the cell-mediated immune responsiveness of the synovium determined by lymphokine production by cultured explants. The results suggested that the suppressive effect of the drug on the arthritis was related to the inhibition of cell-mediated immune responsiveness. Prednisolone treatment also had deleterious effect on cartilage proteoglycan metabolism determined both histologically and biochemically. Intra-articular administration of triamcinolone hexacetonide (three injections of 2 mg per joint at fortnightly intervals) also reduced the swelling and histopathological changes, although there was no effect on circulating antibody levels.