Monoclonal anti-islet cell autoantibodies from C57BLKsJ db/db diabetic mice.

We have developed hybridomas producing anti-islet cell monoclonal autoantibodies (IC-MC auto Ab), by fusion of splenocytes from C57BLKsJ db/db diabetic mice with the SP2/O-Ag 14 myeloma. These IC-MC auto Ab were screened by an enzyme-linked immunosorbent assay, for their binding-ability to RINm5F insulinoma cells. Twenty IC-MC auto Ab were produced, which have differing immunoglobulin isotypes. Four of them induced a complement-dependent lysis of RINm5F cells in vitro, while the others did not. These two populations of auto Ab reflect the duality found in the intact db/db mouse. Immunoperoxidase procedures demonstrated that IC-MC auto Ab bound specifically to beta cell antigens of control pancreatic sections, in a similar pattern as auto Ab spontaneously "trapped" in the islets of db/db mice. Electron microscopic studies with an immunogold staining suggested that target antigens for IC-MC auto Ab were predominantly located in the cytoplasmic matrix of beta cells and, to a lesser extent, on their membranes. These antibodies represent powerful reactives for the studies concerning with the pathogeny of diabetes.