Human monoclonal islet cell antibodies from a patient with insulin-independent diabetes mellitus reveal glutamated decarboxylase as the target antigen

Anti-human IgG-coupled magnetic beads were used to isolate IgG-positive cells from prediabetic and newly diagnosed insulin-dependent diabetes mellitus in order to screen for cytoplasmic islet cell antibodies. Six islet cell-specific beta-cell lines were stabilized on the monoclonal level which did not react to other body tissues except for pancreatic islets and neurons of rat cerebellar cortex. Further tests revealed that glutamate decarboxylase was the target antigen for monoclonal islet cell antibodies.