Detection of dendritic cells in the non-obese diabetic (NOD) mouse islet pancreas infiltrate is correlated with Th2-cytokine production

We investigate the role played by dendritic cells (DCs) in the non-obese di abetic (NOD) mouse pancreas. The early peri-islet, nondestructive infiltrat ion phase, and intra-islet, destructive infiltration phase, which immediate ly precedes overt diabetes, are studied. Results,show that infiltrating cel ls are la-b, ICAM-1, and, mainly, MIDC-8 immunoreactive (ir). These data fr om si lice-treated animals and ultrastructural observations strongly suppor t the hypothesis that DCs are both la-b-ir and ICAM-1-ir and that they exer t a pivotal role during the period of early infiltration. This is a novel f inding for NOD mice and increases the interest for this protective cell typ e during the rather complex islet infiltration process. Moreover, the cytok ine profile demonstrates that Th2 protective cytokines are specific for per i-islet infiltrate. Disappearance of DCs from the infiltrate is concomitant with both the formation of intra-islet infiltration and the increase in pr oinflammatory Th1 cytokine levels. This further supports the hypothesis tha t DCs may exert a protective role against diabetes development. (C) 1999 Wi ley-Liss, Inc.