Fig. 2.

Effects of 1,25(OH)₂D₃are greater on naïve than memory T cells. Naive and memory CD4⁺ T cells were purified from the peripheral blood of healthy controls and stimulated with autologous monocytes and anti-CD3 in the presence or absence of 1,25(OH)₂D₃ (+1,25D). Frequency of cells expressing IL-17, IFNγ and IL-21 was quantified at seven days and expression of CTLA-4 and FoxP3 measured at four days by flow cytometry. (A) Frequencies of cytokine positive cells and CTLA-4 median fluorescence intensity (MFI) summarised for n = 6 donors for vehicle (closed symbols) and 1,25(OH)₂D₃ (+1,25D)-treated cells (open symbols). (B) The effect of 1,25(OH)₂D₃ on IL-17, IFNγ and IL-21 was compared for naïve and memory T cells by frequency of positive cells under untreated/1,25D conditions. A lower frequency limit of 0.001% was used for these calculations. 1,25(OH)₂D₃ effect on CTLA-4 was estimated by MFI under 1,25D/untreated conditions. Significant differences were tested using Wilcoxon matched pairs tests. ns = non-significant, * = P < 0.05, ** = P < 0.01, *** = P < 0.001.