Signore A.#, A. Annovazzi#, E. Procaccini#, P.E. Beales, J. Spencer, R. Testi$ and G. Ruberti&

#Nu.M.E.D. Group, Clinica Medica II, University La Sapienza, Rome, Italy, $Department of Experimental Medicine and Biochemical Sciences, University of Rome "Tor Vergata", &Department of Immunobiology, Institute of Cell Biology, C.N.R, Rome.

Corresponding author: A. Signore (a.signore@caspur.it)

The non-obese diabetic (NOD) mouse is widely used to study the pathogenesis of insulin-dependent diabetes mellitus. However, the mechanisms responsible for beta-cell destruction, in this model, are still poorly defined. The CD95/CD95L system among other effector systems has been implicated in beta-cell death. In this study we investigated in NOD, non-obese resistant (NOR) and Balb/c mice the expression of CD95 and CD95L in alpha and beta pancreatic cells by immunohistochemistry and immunofluorescence. We demonstrate that alpha cells in the islets of Langherans constitutively express CD95L forming a natural shield around beta cells.