Fig. 4

Antigen-specific CD4 T-cell responses were comparable between WT and Il21r KO mice with CIA. a Representative dot plot analysis of intracellular CD154 expression in WT (upper) or Il21r KO (lower) CD4 T cells 35 days after CIA induction. CD154 within CD4 T cells was stained after ex-vivo stimulation with nothing (left), CII (middle), or PPD (right). Numbers (upper right quadrant) indicate the percentage of CD154⁺ cells in CD4 T cells. b Absolute numbers of CD154⁺ CD4 T cells in WT mice (filled symbols) or Il21r KO mice (open symbols) during the course of CIA. IFN-γ (c) and IL-17 (d) secretion of draining LNs in WT mice (filled column) or Il21r KO mice (open column) 35 days after CIA induction. Both cytokines of supernatants were measured by ELISA after ex-vivo stimulation with CII (middle) or PPD (right). Error bars represent mean ± SEM. Statistical significance was analyzed by two-way ANOVA with repeated measures (b–d). Data are representative of three independent experiments. CII type II collagen, IFN interferon, IL interleukin, Il21r KO IL-21 receptor knockout, PPD purified protein derivative, WT wild type