Résumé : AIMS/HYPOTHESIS: IFN-gamma, together with other inflammatory cytokines such as IL-1beta and TNF-alpha, contributes to beta cell death in type 1 diabetes. We analysed the role of the transcription factor interferon regulatory factor (IRF)-1, a downstream target of IFN-gamma/signal transducer and activator of transcription (STAT)-1, in immune-mediated beta cell destruction. METHODS: Islets from mice lacking Irf-1 (Irf-1 (-/-)) and control C57BL/6 mice were transplanted in overtly diabetic NOD mice. Viability and functionality of islets were evaluated in vitro. Chemokine expression by Irf-1 (-/-) islets and INS-1E cells transfected with Irf-1 short interfering RNA (siRNA) was measured by real-time PCR as well as in functional assays in vitro. RESULTS: IRF-1 deletion in islets was associated with higher prevalence of primary non-function (63% vs 25%, p