A77 1726 increases the production of intracellular IL-1 receptor antagonist (IL-1Ra) in human synovial fibroblasts and de-differentiated articular chondrocytes. (a) Human osteoarthritis (OA) synovial fibroblasts (passage 1) and (b) de-differentiated human OA articular chondrocytes (passage 5) were stimulated (black columns) or not (white columns) with 100 μmol/l A77 1726 alone or in combination with 1 ng/ml IL-1β for 48 hours. A77 1726 was added 2 hours before stimulation with IL-1β. IL-1Ra concentrations in cell lysates were measured by ELISA. Results are represented as means ± SEM for three determinations in a representative experiment. Similar results were obtained with cells from five different donors (four OA and one rheumatoid arthritis sample) for synovial fibroblasts and two different donors (two OA samples) for de-differentiated chondrocytes. *P < 0.05 versus control; &P < 0.01 versus IL-1β alone.