Influence of the age of erythrocytes on their insulin receptors.

Specific binding of 125I-insulin to erythrocyte receptors increased linearly with reticulocyte count in routine blood specimens from hospitalized patients. Specific binding as high as 30-35% is observed in patients with reticulocyte counts in the range of 20-25% compared with 9.0 +/- 0.5% specific binding in healthy control subjects with normal reticulocyte counts. It is concluded that care must be exercised in interpreting elevations of specific 125I-insulin binding to erythrocyte receptors as due to specific disease processes without considering how the disease itself may alter mean erythrocyte age at the time of sampling.