Fig 4. Supernatants of 1,25D^diff-DCs promote differentiation of IL-22-secreting T cells.

Monocytes were differentiated into DCs with rGM-CSF and rIL-4 in media with 10% FCS in the presence (1,25D^diff-DCs) or absence (serum-DCs) of additional 1,25D (10⁻⁸ M). 1,25D^diff-DCs and serum-DCs were stimulated with TLR2/1L (1 μg/ml) in fresh media and supernatants were collected after 18–24 hours. Subsequently, TLR2/1-induced 1,25D^diff-DC and serum-DC supernatants were added to naïve CD4⁺ T cells activated with CD3/CD28-coated beads. As a control, naïve CD4⁺ T cells were incubated with CD3/CD28-coated beads without addition of DC supernatants (beads only). After five days, rIL2 was added to all cultures. On day 12, T cells were re-stimulated with PMA/Ionomycin in fresh media and cytokine secretion evaluated after 18–24 hours. Levels of T cell-derived IL-22, IL-17a and IFN-γ were assessed by ELISA (mean of cytokine levels in ng/ml ± SEM, IL-22 n = 15, IL-17a/IFN-γ n = 13). *p<0.05, **p<0.01