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. 2012 Jun 30;12(3):113–117. doi: 10.4110/in.2012.12.3.113

Figure 1.

Figure 1

Human islet cell death by IFNγ/TNFα synergism. Single human islet cells were incubated with the cytokine combination for 5 days before assay. A combination of IFNγ (1,000 U/ml) and TNFα (10 ng/ml), but neither cytokine alone, induced human islet cell death as measured by MTT assays. IL-1β (17.5 ng/ml) had negligible effects. Graphs from one representative experiment among three independent experiments are shown. Values represent the means±SD from triplicate experiments. The means were compared using Student's unpaired t test. **p<0.01; ns, not significant (A). Apoptosis of human islet cells induced by IFNγ/TNFα. Nuclear condensation demonstrated by Hoechst staining (upper) or electron microscopy (lower) revealed that human islet cell death by IFNγ/TNFα was a classical apoptosis (B). IFNγ activates STAT1 and induces IRF-1 expression in human islet cells. Western blot analyses demonstrated that treatment of human islet cells with IFNγ (1,000 U/ml) for 30 min induced STAT1 phosphorylation (C). IFNγ also induced IRF-1 expression after 48 h of treatment (D).