Interleukin 10 suppresses the expression of interleukin 17 and retinoid-related orphan receptor γt in local joints of mice with collagen-induced arthritis. (A) The levels of interleukin 17 (IL-17) in the knee joint synovial fluid of IL-10-knockout (IL-10−/−) mice and wild-type (WT) mice with collagen-induced arthritis (CIA) were measured by using an enzyme-linked immunosorbent assay (n = 5). (B) Expression levels of IL-17 mRNA in synovial tissue of IL-10−/− mice and WT mice with CIA were measured by performing quantitative RT-PCR (qRT-PCR) experiments (n = 5). (C ) Expression levels of retinoid-related orphan receptor γt (RORγt) mRNA in synovial tissues of IL-10−/− mice and WT mice with CIA were measured by qRT-PCR (n = 5). (D ) The protein levels of IL-17 and RORγt in synovial tissues of IL-10−/− mice and WT mice with CIA were determined by Western blot analysis and then quantified by densitometry. β-actin was used as an internal control (n = 3). Data in (A) through (D) were obtained on day 45 after type II collagen immunization and are mean ± SEM. *P < 0.05; **P < 0.01.