CBD induces CD25 and FOXP3 on CD4+ T cells in response to Us/o, S/o and s3/28 stimulation. CBD is most effective in inducing CD4+CD25+FOXP3+ T cells in response to Us/o. Us/o + CBD increased FOXP3 expression on CD4+ cells derived from FOXP3-GFP mice. Us/o + CBD induced FOXP3 in pre-purified CD4+CD25− and CD4+CD25+ T cells. Us/o + CBD-induced CD4+CD25+ T cells suppressed responder cell proliferation.