Lack of expression of antigens for islet cell antibodies in rat fetal pancreas

It is not clear yet when pancreatic islet cells begin to express antigens for islet cell antibodies (ICA). Therefore, we studied whether human ICA-positive sera, crossreacting with adult rat islet cells, react with fetal and neonatal rat islet cells immunohistologically. The ICA did not react with fetal islet cells. On the other hand, neonatal islet cells over 2-3 weeks of age expressed the reactivities almost similar to those of the adult. It was suspected that pancreatic islet cells started to express their antigens to induce ICA gradually after birth.