OBJECTIVEAnnexin-1 (Anx-A1) has been recently shown to play a key role in T-cell activation and to be highly expressed in T cells from RA patients. Here, we investigated the effects of glucocorticoids (GCs) on Anx-A1 expression in T cells in vitro and in vivo.METHODSTo evaluate the effects of dexamethasone (Dex) on Anx-A1 expression, human peripheral blood T cells were incubated with Dex and then analysed by real-time PCR and western blotting. Similar experiments were carried out in vivo by measuring Anx-A1 levels in T cells from patients with RA before and after administration of steroids.RESULTSIncubation of T cells with Dex decreased Anx-A1 levels in a time-dependent fashion and almost abolished its expression after 12 h. Stimulation of T cells pre-incubated with Dex for 12 h with anti-CD3/CD28 led to significant reduction of IL-2 production. Addition of human recombinant Anx-A1 to Dex-treated cells reversed the inhibitory effects of the steroids on anti-CD3/CD28-induced IL-2 production. Treatment of RA patients with steroid decreased Anx-A1 expression in T cells.CONCLUSIONSGCs suppress Anx-A1 expression in T cells in vitro and in vivo. These results provide evidence for a novel pathway by which steroids regulate the adaptive immune response and suggest that Anx-A1 may represent a target for the treatment of autoimmune diseases.