A 53-yr-old male patient with insulin-resistant diabetes was found to have circulating inhibitors of both insulin and somatomedin-C binding. Serum obtained from the patient at the time of initial presentation inhibited 50% of both 125I-insulin and 125I-SM-C binding to IM-9 lymphocytes at dilutions of 1:150. Spontaneous improvement in the patient's diabetic state was associated with a simultaneous and equal decrease in the serum inhibitory titers for both radioligands. Scatchard analysis indicated that the observed serum-induced decrease in both insulin and SM-C binding was due to decreased receptor affinity, with no alteration in receptor number. The serum inhibitors of both insulin and SM-C binding were precipitated equally by Staph-A and also by 40% ammonium sulfate, suggesting they were immunoglobulins. The observation of naturally occurring autoantibodies against both the insulin and SM-C receptors suggests a structural homology between the two receptors.
Simultaneous Inhibition of Insulin and Somatomedin-C Binding to Cultured IM-9 Lymphocytes by Naturally Occurring Antireceptor Antibodies
Ron G Rosenfeld, David Baldwin, Laura A Dollar, Raymond L Hintz, Jerrold M Olefsky, Arthur Rubenstein; Simultaneous Inhibition of Insulin and Somatomedin-C Binding to Cultured IM-9 Lymphocytes by Naturally Occurring Antireceptor Antibodies. Diabetes 1 November 1981; 30 (11): 979–982. https://doi.org/10.2337/diab.30.11.979
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