MODULATION AND DETECTION OF IDDM BY MEMBRANE-ASSOCIATED ANTIGENS FROMTHE ISLET BETA-CELL LINE NIT-1

We have utilized the NOD islet beta-cell line NIT-I to monitor p-cell specific autoantibodies and to investigate the modulation of IDDM in N OD mice by NIT-1 membrane associated antigens. The sera from diabetic but not from pre-diabetic or protected NOD mice strongly stained NIT-I cells in FAGS analysis. The cell surface antigens on NIT-I cells were trypsin-sensitive. NIT-1 cells could not be stained by anti-mouse GAD 67 antibody; however, we could demonstrate the presence of GAD65 and G AD67 mRNA by RT-PCR. Longitudinal analysis of anti-NIT-1 antibodies sh owed that these antibodies were present in the neonates but disappeare d after weaning. Sonicated NIT-1 cell membrane preparations protected NOD mice from diabetes when injected intravenously in 5 week old mice. The protection was associated with reduced cytotoxic activity and ele vated Th2-like responses as indicated by IgG1 antibodies against the N IT-1 cells. Subcutaneous injection of sonicated NIT-1 membranes or the injection of control red blood cell membranes failed to induce protec tion. We conclude that NIT-1 cell membranes do not express GAD but con tain other antigens that are important in the development and preventi on of IDDM. These antigens could be useful for the diagnosis of diabet es by monitoring autoantibody levels and for the modulation of IDDM by immunotherapy. (C) 1997 Academic Press Limited.