Significant suppression of collagen-induced arthritis (CIA) in RORγt Tg mice. Wild-type (WT) C57BL/6 mice (n = 19) and RORγt Tg mice (n = 15) were immunized intradermally with chicken type II collagen (CII) emulsified with complete Freund’s adjuvant (CFA) on days 0 and 21. (A) Incidence of arthritis. (B) Severity of CIA. Data obtained from three independent experiments. (C) At day 42 post first CII immunization, joint pathology was evaluated on decalcified hematoxylin and eosin-stained sections. Inflammation and bone erosion scores were assessed in both groups. Data are mean ± standard error of the mean. *P < 0.05, **P < 0.01, versus C57BL/6 mice, Student’s t-test.