Role of IL-10 in the induction of Tregs and in their suppressive function. Control and GILZ-transfected DCs were pulsed with PPD and used to stimulate CD4⁺ T lymphocytes, which were then added to CFSE-labeled PBMCs stimulated with PPD. Proliferation of CD4⁺ responders was assessed by flow cytometry. (A) IL-10 is involved in the induction of Tregs. An anti–IL-10 mAb or its isotype control was added to the coculture of DCs and CD4⁺ T lymphocytes. (B) Production of IL-10 by Tregs is involved in their suppressive function. An anti–IL-10 mAb or its isotype control was added to the coculture of CD4⁺ T lymphocytes and responders. Results are representative of 3 experiments.