Interleukin 10 suppresses retinoid-related orphan receptor γt expression in macrophages of mice with collagen-induced arthritis. (A) Macrophages in the joint tissues and synovial fluid (SF) taken from interleukin 10–knockout (IL-10−/−) mice and wild-type (WT) mice with collagen-induced arthritis (CIA) on day 45 after chicken type II collagen (CII) immunization were then isolated. The total cellular RNA was extracted and analyzed for retinoid-related orphan receptor γt (RORγt) mRNA by quantitative RT-PCR. Data are mean ± SEM (n = 3). *P < 0.05. (B) Macrophage proteins were extracted and Western blot analysis was performed to detect protein levels of RORγt, which were then quantified by densitometry. β-actin was used as an internal control. Data are mean ± SEM (n = 3). *P < 0.05. (C) Macrophages isolated from the joint tissues and SF of IL-10−/− and WT mice with CIA on day 45 after immunization were stained with fluorescein isothiocyanate–conjugated F4/80 (green) or phycoerythrin-conjugated RORγt (red) and analyzed by confocal microscopy. Bar = 25 μm.