Class-II and IL 2 receptor positive cells in the pancreas of NOD mice

The aberrant expression of Class-II molecules on pancreatic B cells in Type 1 (insulin-dependent) diabetes is still a matter of debate. In order to verify if Class-II molecules are expressed on islet cells in the NOD mouse we have studied 21 female mice of different ages (5 to 22 weeks). Serial cryostat pancreas sections were stained with monoclonal rat antibodies against Class-II antigens (P7/7) and the IL2 receptor (AMT-13). Our results show no Class-II expression by endocrine cells at any age, whereas about 25–32% of mononuclear cells infiltrating the islets were Class-II positive, and only 6–9% were IL2 receptor positive. No staining, except of occasional tissue macrophages, was observed in the pancreas of BALB/c, CBA or B10.SCSN mice. Our data are in contrast with those recently published and therefore the reality of expression of Class-II molecules by islet cells of NOD mice should be viewed with caution.