Fig. 6

IDO⁺CD11b⁺ DC induce antigen-specific CD4⁺CD25⁺ Tregs and are juxtaposed to Tregs. Increased generation of CD4⁺CD25⁺ Foxp3⁺ T cells is mediated through an indoleamine 2,3-dioxygenase (IDO)-dependent mechanism. a,b For regulatory T cell induction, isolated CD4⁺CD25⁻ T cells (1 × 10⁵/well) were cultured for three days with CD11b⁺ DC (1 × 10⁵/well) from EGCG-fed or vehicle-fed CIA mice in the absence or presence of type II collagen (CII, 10 μg/ml). 1-MT was added to the indicated cultures. CD4⁺ cells were first gated and then plotted as CD25 versus Foxp3 as determined by flow cytometry. Numbers represent the percentage of CD4⁺ CD25⁺ Foxp3^bright positive cells and are representative of three independent experiments. c Immunofluorescent analysis of IDO and Foxp3 expression in the spleen. Spleens from EGCG-fed or vehicle-treated CIA mice were fixed and stained with antibodies specific for mouse IDO (red) and Foxp3 (green); original magnification, X200. Photomicrographs shown are representative of three independent experiments. d Arthritis scores for vehicle-fed, EGCG-fed, or EGCG-fed mice given 2 mg/ml of 1-MT solution in drinking water bottles for three weeks. Values are presented as the mean ± standard error of the mean, and represent two independent experiments; in total eight mice were examined for each group