Antibodies against gastrointestinal carcinoid tumors in IDDM.

In this study, 92% of patients' serums known to contain antibodies against islet cells, including the Juvenile Diabetes Foundation provisional reference serum, had antibodies reacting with gastrointestinal carcinoid tumors. Twelve percent of the control serums from healthy individuals bound to carcinoid cells, and 2% bound to islet cells. Seventy-five percent of the children with newly diagnosed insulin-dependent diabetes mellitus had carcinoid tumor antibodies, and 83% had islet cell antibodies. These findings suggest that antigenic determinants are shared between endocrine cells of islets of Langerhans and neuroendocrine tumors of the same embryological derivation. Carcinoid tumors may not only provide an alternative source for islet cell antibody assays but also supply material for isolation of antigens possibly involved in the immunopathogenesis of diabetes.