1. A study of the life span of the erythrocyte in patients with advanced neoplastic disease was performed by transfusing blood from 23 hospitalized patients into 53 healthy volunteers.
2. The Ashby technic for red cell labeling was used alone in 16 instances, Cr51 technic in 52 instances, and a combination of the 2 technics in 8 instances.
3. Normal or nearly normal life spans were suggested by the slopes of curves in 15 instances where whole blood from patients was transfused into volunteers.
4. Some shortening of the life span of the patient’s red cells was noted when these cells, separated from the plasma, were transfused into volunteers or back into patients, possibly related to the handling during plasma removal.
5. Control studies using either Cr51 or Ashby labeling technic indicated a normal life span of approximately 120 days in the volunteers employed could be achieved by each method.
6. Values obtained with Cr51 were so similar to those using Ashby labeling that the easier Cr51 technic is recommended for future studies.
7. The normal erythrocyte transfused into patients with neoplastic disease may have a moderate to considerably shortened life span.
8. These studies seem to demonstrate an absence of an intrinsic defect in the erythrocytes of patients with neoplastic disease, and further favor the presence of a hemolytic plasma factor of considerable importance in the pathogenesis of the anemia of cancer.