The prevalence of islet cell antibodies in Japanese insulin-dependent and non-insulin-dependent diabetic patients studied by indirect immunofluorescence and by a new method.

Islet cell antibodies (ICA) were measured in Japanese patients with insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) by a standard, indirect immunofluorescence method (IF method) and by a newly established, three-layer immunofluorescence method applying a biotin-avidin system (BAS method). In addition, the relationship between ICA and HLA was studied in IDDM patients. ICA titers detected by the BAS method correlated well with those determined by the standard IF method (rS = 0.987, P less than 0.01). The BAS method had about an eightfold higher sensitivity for ICA than the IF method. The overall prevalence of ICA detected by the BAS method (ICA-BAS) versus that by the IF method (ICA-IF) was 41% (82/198) versus 28% (56/198) in IDDM patients and 3% (19/593) versus 2% (14/593) in patients with NIDDM. In IDDM patients, ICA-BAS was all positive less than 1 mo after the onset of diabetes, while the prevalence of ICA-IF was 83% (20/24) during the same period. The prevalence of ICA-IF decreased rapidly with the duration of disease, reaching a value of 6% (3/55) in the patients with a disease duration of 10 yr or more. The incidence of ICA-BAS also decreased with the duration of disease, although to a lesser degree than ICA-IF. No association was found between HLA types and persistence of ICA-BAS or -IF.(ABSTRACT TRUNCATED AT 250 WORDS)