BLOOD DONATION LEADS TO A DECREASE IN NATURAL-KILLER-CELL ACTIVITY - A STUDY IN NORMAL BLOOD-DONORS AND CANCER-PATIENTS

Transfusion-induced immunosuppression has long been known to be beneficial for organ transplantation patients, but recent retrospective studies suggest that blood transfusions may be detrimental for patients with cancer. If autologous blood is used to avoid immunosuppression, the assumption is that the procedure, involving blood donation, is immunologically neutral. In the present study, this assumption was evaluated by monitoring 33 normal blood donors and 16 colorecteal cancer patients before and after donation of 1 (500 mL) and 2 units of blood, respectively. The cancer patients belonged to the autologous arm of a randomized trial in which the effects of allogeneic versus autologous blood on cancer prognosis were studied. The patients donated 2 units of blood with an interval of 3 to 4 days between donations. Flow cytometric analysis revealed that blood donation by normal donors and cancer patients had no effect on the proportion of B, T, and natural killer (NK) cells. Only the total number of lymphocytes was significantly decreased in the normal donors on Day 12 after donation. Blood donation had no significant effect on T-cell function assessed by phytohemagglutinin stimulation in normal donors or in cancer patients donating 2 units of blood. A significant depression of NK cell function (88% and 74% of predonation levels) was observed in normal donors on Days 2 and 5 after donation; on Day 12, the activity was again normal. Colorectal cancer patients had a significantly depressed NK cell activity (54% of predonation activity) on Day 12 after the first donation. Before donation, the NK cell activities of blood donors and cancer patients were similar (45.6 +/- 4.3% and 41.4 +/- 3.6%, respectively, at the 50:1 ratio). Before donation, the number of NK cells correlated significantly with NK cell activity, but, after donation, such a correlation was lacking. This study indicates that blood donation, especially the donation of 2 units, leads to a depressed NK cell activity. If confirmed in a larger study, this finding may have important implications for cancer patients undergoing surgery.