title: Islet-cell antibodies (ICA) in diabetes mellitus (evidence of an autoantigen common to all cells in the islet of Langerhans).
abstract: Pancreatic islet-cell antibodies (ICA) are important markers for two subtypes of insulin-dependent diabetes mellitus and stain the entire islet in the standard immunofluorescence test. This could indicate either a mixture of antibodies each directed against one cell type, or a population of antibodies reacting with a single antigen common to the endocrine pancreas. In the present experiments such a common antigen was demonstrated visually by application of animal antisera raised to each of the 4 pancreatic hormones, together with ICA-positive sera in a four-layer double immunofluorescent technique employing green and red anti-Ig conjugates. Double exposure photographs demonstrated that the patients' sera reacted equally with the different endocrine cells. The ICA antigen did not cross-react with gastric glucagon- or somatostatin-cells. By contrast, human antibodies against glucagon-cells (GCA) or somatostatin-cells (SCA) reacted with discrete antigens specific to each cell type and in 50% of cases the antibodies also stained the respective endocrine cells in the gastrointestinal tract. These refined discriminatory properties of human autoantibodies may lead to a better understanding of the intracellular membrane systems in these important endocrine organs.
mesh_terms: D000941:Antigens / Q000302:isolation & purification; D001323:Autoantibodies / Q000302:isolation & purification; D001324:Autoantigens / Q000302:isolation & purification; D003429:Cross Reactions; D003920:Diabetes Mellitus / Q000276:immunology*; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D005934:Glucagon / Q000276:immunology; D006801:Humans; D007515:Islets of Langerhans / Q000276:immunology*; D013004:Somatostatin / Q000276:immunology
chemical_list: D000941:Antigens; D001323:Autoantibodies; D001324:Autoantigens; D000939:Epitopes; D013004:Somatostatin; D005934:Glucagon