Icaritin inhibits T cell activation and prolongs skin allograft survival in mice

► Icaritin could dose-dependently inhibit activated murine T cells proliferation. ► Icaritin could down-regulate CD25 expression and inhibit Th1 cytokines IL-2 and IFN-γ production. ► Icaritin could prolong murine allograft skin survival with mechanism different to CsA. ► Icaritin might be used to treat Th1 dominated immune diseases by interfering T cells activation.