The Use of ¹²⁵I as a Membrane Protein Label for Erythrocyte Survival Studies

Radioactive iodide, incubated with erythrocytes in the presence of lactoperoxidase and hydrogen peroxide, is covalently bound to membrane proteins. Using this technique, rabbit erythrocytes were labeled with ¹²⁵I, reinjected into the donors, and erythrocyte survivals determined. The values for the erythrocyte half-lives and the shape of the decay curves were comparable to those reported using DF³²P. Following hemolysis of erythrocytes double labeled with ¹²⁵I and ⁵¹Cr, radioactivity from both these isotopes appeared mainly in liver, lung, kidney, spleen, and urine. Enzymatic iodination provides a noneluting label of erythrocyte membrane proteins for the study of survival, sequestration and turnover of this red cell component.