Human islets of Langerhans express Fas ligand and undergo apoptosis in response to interleukin-1β and Fas ligation

IDDM results from a progressive loss of pancreatic beta-cells that, in humans, may be triggered by a combination of genetic and environmental factors. Recently, attention has been focused on the hypothesis that the loss of beta-cells is initiated by inappropriate induction of apoptosis. We now demonstrate that human islets of Langerhans undergo apoptosis upon exposure to interleukin-1 beta. The cytokine also sharply increases the number of cells that enter apoptosis on treatment with a stimulatory anti-Fas antibody. Western blotting and immunocytochemistry clearly show for the first time that human pancreatic beta-cells normally express Fas ligand. The results suggest that human islet cells are primed to undergo apoptosis by interleukin-1 beta and that this involves the close association between cell-surface Fas and its ligand.