Combined effects of IL-17 (20 ng/ml) plus IL-1β (10 ng/ml) or IL-17 (20 ng/ml) plus TNF-α (10 ng/ml) on the expression of TSG-6 protein. Fibroblast-like synoviocytes (SFCs) were cultured for 48 hours with the cytokines indicated below. Cells were lysed, separated, blotted, and probed with a TSG-6 antibody as described in Materials and methods. Lanes 1–6, SFCs of patient 1; lanes 7–12, SFCs of patient 2. Lanes 1 and 7, control; lane 2, IL-17; lanes 3 and 8, IL-1β; lanes 4 and 9, IL-17 plus IL-1β; lanes 5 and 10, TNF-α; lanes 6 and 11, IL-17 plus TNF-α; lane 12, IL-17 plus anti-IL-17 antibody. The intensity was analyzed densitometrically and normalized to the intensity of the appropriate control.