HCVc and HCVcc induce suppressive monocytes to inhibit autologous CD4⁺ T cell activation and expand CD4⁺Foxp3⁺ Tregs in an IDO1-dependent manner.

<p>CFSE-labeled CD4⁺ T cells were stimulated with pre-coated OKT3 (CD3 mAb) and CD28 antibody, and co-cultured with HCVc- and HCVcc-treated autologous monocytes in the absence or presence of 1-MT. Foxp3 expression and proliferation of the autologous CD4⁺ T cell were evaluated by intracellular staining and flow cytometry. One of five representative experiments is shown as histogram (A) and contour (B). The proliferation of CD4⁺ T cells (C) and CD4⁺Foxp3⁺ T cells (E) are statistically analyzed from five experiments. The supernatants were collected and assayed by ELISA for IFN γ production (D). The bars represent the standard error of the mean. Abbreviation: 1-MT, 1-methyl-DL-tryptophan.