PRODUCTION OF ISLET CELL ANTIBODIES FROM EPSTEIN-BARR VIRUS-TRANSFORMED PERIPHERAL-BLOOD LYMPHOCYTES IN TYPE-1 (INSULIN-DEPENDENT) DIABETIC-PATIENTS

Islet cell antibodies are usually detected in the sera of almost all Type 1 (insulin-dependent) diabetic patients within several months after onset of the disease. The antibodies then disappear quite early during the course of the disease. The present study was undertaken to detect islet cell antibody-producing clones in peripheral blood lymphocytes of Type 1 diabetic patients whose islet cell antibodies could not be detected in sera. Epstein-Barr virus-transformed lymphocytes were employed to enhance the production of antibodies and to detect the clones from peripheral blood lymphocytes. Peripheral blood lymphocytes were obtained from 40 islet cell antibody-negative Type 1 diabetic patients, 10 antibody-positive Type 1 diabetic patients, 30 Type 2 (non-insulin-dependent) diabetic patients and 40 normal control subjects. Epstein-Barr virus-transformed lymphocytes were cultured for 4 weeks and the culture supernatants were used for assay of islet cell antibodies. Islet cell antibody assays were performed by immunohistochemical methods using peroxidase-labelled protein A for IgG antibodies, peroxidase-labelled anti-human IgM antibodies for IgM antibodies and fresh frozen human pancreatic tissue. IgG-islet cell antibodies were detected in 26 islet cell antibody-negative patients (65%), eight antibody-positive patients (80%) and one Type 2 diabetic patient (3%) in the culture supernatants. Islet cell antibodies in the supernatants could not be detected in any of the control subjects. IgM-islet cell antibodies could not be detected in any of the patients or control subjects. These findings indicate that islet cell antibody-producing clones exist in peripheral blood lymphocytes from Type 1 diabetic patients whose islet cell antibodies cannot be detected in their sera and IgG-islet cell antibodies might be a specific characteristic of Type 1 diabetes. The detection of islet cell antibodies from Epstein-Barr virus-transformed lymphocytes may be useful in examining the role of autoimmune mechanisms in the development of disease.