Islet cell surface antibodies in spontaneously diabetic BB rats

Antibodies to normal Wistar rat islet cells are often found in newly diagnosed diabetic BB rats. It was tested if antibodies in BB rats bind to cells from a cloned insulin-producing, rat-insulinoma cell line, RIN 5F, using a protein A-radioligand assay for islet cell surface antibodies. A close correlation was found between the binding of antibodies to islet cells and to RIN 5F cells. Islet cell surface antibodies reactive with RIN 5 F cells were determined in two litters of BB rats, born by diabetic, islet cell surface antibody positive parents. A high incidence (85%) of diabetes was found among 13 offsprings, the mean age of onset being 88 days. At 44 days of age before diabetes was diagnosed, 95% of 20 offsprings were islet cell surface antibody positive. There was no difference in antibody-levels between diabetic and non-diabetic rats. It is concluded that BB rats have circulating antibodies reactive with surface determinants on the RIN-5F insulin-producing cell line. There was a high prevalence of islet cell surface antibodies among young, yet unaffected BB rats.