Islet cell cytoplasmic and surface antibodies' prevalence and beta cell specificity of islet cell surface antibodies in some subjects with putative islet cell autoimmunity.

In human sera two methods of islet cell cytoplasmic antibody (ICA) detection (on Bouin-fixed or cryostate sections of human pancreas) and the islet cell surface antibody (ICSA) method on isolated rat islet cells were compared. The ICA detection on Bouin-fixed sections was more sensitive than that on cryostate sections. In two groups of subjects with putative islet cell autoimmunity ICA prevalence was higher than ICSA prevalence. However, a weak correlation between both types of antibodies was established. In one group of healthy subjects with cytotoxic serum against rat beta cells a high prevalence of ICSA was found, whereas none of them had ICA. Defined on the basis of a positive immunofluorescence on rat islet cells, ICSA positive sera of newly diagnosed IDDM patients reacted to a significantly higher percentage with beta cells than did normal controls. In conclusion, of all methods compared ICA detection on Bouin-fixed pancreas sections seems to be the most suitable method for the detection of an islet cell autoimmunity.