Fig. 1.

Anti-inflammatory effects of 1,25(OH)₂D₃are reduced in T cells from synovial fluid compared to peripheral blood. Mononuclear cells from the peripheral blood of healthy controls (HC) and the blood and synovial fluid (SF) of RA patients were stimulated with anti-CD3 for seven days in the presence or absence of 1,25(OH)₂D₃ (+1,25D) and frequencies of IL-17 + and IFNγ+ CD4⁺ T cells quantified by flow cytometry (A). Representative bivariate plots of IL-17 versus IFNγ expression by CD4⁺ T cells showing IL-17+/IFNγ- (Th17), IL-17+IFNγ+ (Th17.1) and IL-17-IFNγ+ (Th1) subsets for cells from RA blood vs RA SF. (B). Significant effects of 1,25(OH)₂D₃ were tested for HC (n = 9), RA blood (n = 12), RA SF (n = 11) by Wilcoxon matched pairs or Mann Whitney nonparametric tests as appropriate (C). Effect of 1,25(OH)₂D₃ on Th17, Th17.1 and Th1 populations quantified by frequency in respective gate under untreated/1,25D conditions. Significance was tested by repeated measures two-way ANOVA. ns = non-significant, * = P < 0.05, ** = P < 0.01, *** = P < 0.001.