Detection of compounds in serum inhibiting insulin binding to erythrocyte receptors.

The erythrocytes were used as a model system to study insulin receptors in diabetic patients with highly increased insulin resistance. The specific binding of 125I-insulin to erythrocytes of these patients was markedly reduced. When erythrocytes prepared from non-diabetic subjects were exposed to serum of these patients, the decrease of insulin binding was reproduced. The binding of insulin showed a displacement curve that is parallel to the control values over the same range of hormone concentration, even in the case when control erythrocytes were preincubated with serum of diabetics with increased insulin resistance. These results indicate the presence of certain component in blood plasma of examined patients which alters insulin binding to receptors. The developed assay provides an efficient method for detection and identification of substances presented in the serum which can influence the binding of insulin to the specific sites as well as its biological effects.