title: Human autoantibodies directed against the human, but not the rat, insulin receptor.
abstract: Prior studies with monoclonal antibodies produced against the human insulin receptor in mice revealed that these antibodies may be species specific. Whether species-specific antibodies to the insulin receptor occur spontaneously in patients, however, has not been previously investigated. Recently, we found that the serum immunoglobulin G from a patient with lupus nephritis, insulin resistance, and hypoglycemia contained multiple subpopulations of antibodies directed at the human insulin receptor. We report herein that one such subpopulation has a high affinity for the human insulin receptor. This antibody subpopulation at 10 nM half-maximally inhibited [125I]insulin binding to human IM-9 lymphocytes, circulating erythrocytes and monocytes, isolated adipocytes, and placenta membranes. In contrast, this antibody subpopulation did not inhibit [125I]insulin binding to isolated rat adipocytes and hepatocytes, even at concentrations as high as 100 nM. These studies indicate that species-specific antibodies can occur spontaneously in patients with antiinsulin receptor antibodies.
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D001323:Autoantibodies / Q000032:analysis*; D005260:Female; D006801:Humans; D007120:Immunochemistry; D007074:Immunoglobulin G / Q000032:analysis*; D008875:Middle Aged; D051381:Rats; D011972:Receptor, Insulin / Q000276:immunology*; D013045:Species Specificity
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; D011972:Receptor, Insulin