Fig. 7. addition of the inhibitor 1-methyl-D-tryptophan (1-MT) of indoleamine 2,3-dioxygenase (IDO) prevents vascular endothelial growth factor (VEGF)-matured dendritic cell (DC) from suppressing lymphocyte proliferation. T cell proliferation stimulated by phytohemagglutinin (PHA) was estimated by flow-cytometry of CD3+ lymphocytes expressing the antigen KI-67 (A) lymphocytes gated on side light scatter (SSC) vs. forward light scatter (FSC) (B), histogram of gated CD3+ cells (C), KI-67 expression on CD3+ lymphocytes without stimuli (1.56% of the cells express the marker) (D), KI-67 expression on PHA-stimulated CD3+ lymphocytes co-cultured with autologous DC matured without VEGF (frequency of positive cells - 37.4%) (E), KI-67 expression on PHA-stimulated CD3+ lymphocytes co-cultured with autologous DC matured with VEGF (frequency of positive cells - 17.6%) and KI-67 expression on PHA-stimulated CD3+ lymphocytes co-cultured with autologous DC matured with VEGF in the presence of 1-MT as inhibitor of IDO (frequency of positive cells - 35%) (representative of 3 independent experiments) (F). FITC: fluorescein isothiocyanate.