A77 1726 increases IL-1 receptor antagonist (IL-1Ra) secretion in human synovial fibroblasts and articular chondrocytes in the presence of tumour necrosis factor (TNF)-α. (a) Human osteoarthritis (OA) synovial fibroblasts (passage 2) and (b) de-differentiated human OA articular chondrocytes (passage 7) were stimulated (closed symbols) or not (open symbols) with 10 ng/ml TNF-α alone or in combination with 50 μmol/l or 100 μmol/l A77 1726 for 48 hours. A77 1726 was added 2 hours before stimulation with TNF-α. IL-1Ra concentrations in culture supernatants were measured by ELISA. Results are represented as means ± SEM of three determinations in a representative experiment. A similar dose dependency was observed in cells obtained from three different donors (three OA samples) for synovial fibroblasts and three different donors (three OA samples) for de-differentiated chondrocytes. *P < 0.001 versus control; &P < 0.001 versus TNF-α alone.