Survival of 59Fe-labeled erythrocytes in cross-transfused equine blood.

Whole blood containing 59Fe-labeled erythrocytes (RBC) and unlabeled serum was transfused from a donor horse on 2 occasions into each of 6 recipient horses. Survival of transfused cells was monitored in the recipients as a function of time after transfusion by measuring RBC radioactivity in the recipients. After the 1st transfusion, RBC concentration of 59Fe remained at 60% to 100% of the transfused dose for 4 days, after which radioactivity values dropped to less than 10% of the dose by 6 days in 3 horses. In the 3 other horses, RBC radioactivity dropped immediately after transfusion, reaching minimal values in approximately 48 hours. After the 2nd transfusion, 1 horse retained 80% of the dose in circulating RBC for 4 days; 2 horses demonstrated a rapid loss of circulating radiolabeled RBC, reaching minimal values in 48 hours; and 2 horses demonstrated minimal radioactivity in the RBC mass even immediately after the transfusion. One horse died of anaphylactic shock during the 2nd transfusion. Erythrocyte compatibility tests, using the direct agglutination test, the antiglobulin test, and the hemolytic test, were not effective in predicting survival of transfused RBC.