ISLET-CELL CYTOPLASMIC ANTIBODY REACTIVITY IN MIDGESTATIONAL HUMAN FETAL PANCREAS

The reactivity of islet cell cytoplasmic antibodies (ICA)-positive and ICA-negative sera of recent onset type 1 diabetic patients was studie d in human fetal pancreata of 12-18 weeks' gestation and compared with the reactivity of these sera in adult human control pancreata. The ai ms of the study were: (1) to observe the presence of ICA staining in h uman fetal islet cells; (2) to compare endpoint titres (in Juvenile Di abetes Foundation units) of ICA-positive patient sera in fetal pancrea ta and adult human control pancreata. Ten ICA-positive sera and eight ICA-negative sera from newly diagnosed diabetic patients and four sera from healthy controls were tested on three human adult and eight huma n fetal pancreata. As in the adult control pancreata. ICA-positive ser a reacted to insulin-, glucagon-, and somatostatin-positive cells of f etal pancreata of all gestational ages. This was observed both in sing le cells and in cells in islet-like cell clusters. Dilution of a refer ence serum gave similar results in both adult and fetal pancreata. In contrast, the ICA-positive patient sera yielded a striking heterogenei ty in fetal as well as in adult pancreata. However, end-point titres b etween adult and fetal pancreata did not differ significantly (P>0.05) . In conclusion, ICA-positive sera from recent onset diabetic patients show that the expression of molecules to which ICA react is present i n all islet cells and starts before week 12 of gestation.