Production of IL-6, IL-8 and nitric oxide by hSFs and hACs: effects of IL-1F8 and IL-1β. Shown is an analysis of the effects of IL-1F8 and IL-1β on production of (a) IL-6 and (c) IL-8 by hSFs, and of (b) IL-6, (d) IL-8 and (e) nitric oxide by hACs. Cells were treated with the indicated cytokine concentrations for 48 hours, as detailed under Materials and method. *P < 0.05 versus control; #P < 0.05 versus 0.1 ng/ml IL-1β; &P < 0.05 versus 500 ng/ml IL-1F8, determined using analysis of variance. IL, interleukin; hAC, human articular chondrocyte; hSF, human synovial fibroblast.