Discordant results in the assay of cytoplasmic islet cell autoantibodies with ELISA and immunohistochemical techniques.

We evaluated 6 batches of a solid phase enzyme-linked immunosorbent assay (ELISA) Isletest-ICA kit commercially available for the determination of autoantibodies to pancreatic islet cells, and compared the results with those obtained by a standardized immunohistochemical method. Following the immunohistochemical determination of autoantibodies to pancreatic islet cells, sera from patients with insulin-dependent diabetes mellitus, both positive and negative for autoantibodies to pancreatic islet cells, were randomly selected and analysed by ELISA. Sera from healthy control subjects, as well as standards recommended by the International Diabetes Workshop (IDW) ICA (Autoantibodies to Pancreatic Islet Cells) Proficiency Program, were included. Of the sera testing positive for autoantibodies to pancreatic islet cells in the immunohistochemical assay, only 14 +/- 5% were found to give a positive reaction in the ELISA. Among the sera from healthy control subjects and pancreatic islet cell autoantibody-negative insulin-dependent diabetes mellitus patients, 25 +/- 7% and 1 +/- 1%, respectively, yielded false-positive readings for autoantibodies to pancreatic islet cells. These results clearly show that the ELISA test presently available does not reliably detect autoantibodies to pancreatic islet cells, even qualitatively. Thus, it cannot be used for screening subjects at risk of developing diabetes.