Immunologic changes after blood transfusion in patients undergoing vascular surgery.

Immunologic changes after blood transfusions cannot be studied ethically in normal individuals. We therefore studied two comparable groups of patients with atherosclerotic cardiovascular disease who received similar drug treatment and experienced a similar degree of surgical trauma, except that one group received an average of 2.5 units of packed red cells at one time period during surgery. We conducted immunologic tests preoperatively and 5, 10, 45 to 60, 90, 180, and 360 days postoperatively. There was no significant difference in all indices tested preoperatively between the two groups. Five and 10 days postoperatively, the absolute numbers of CD3, CD4, CD8, and B cells decreased in both groups; however, the decrease was significantly greater in the transfused group than in the nontransfused group 5 days postoperatively. There was no significant difference in these parameters between the two groups at other time periods tested. At 5 and 10 days postoperatively, the lymphocyte responses to phytohemagglutinin, concanavalin A, and allogeneic lymphocytes in autologous serum were decreased in both groups. However, at 60 days postoperatively, the responses of the nontransfused group became significantly increased, whereas those of the transfused group remained relatively unchanged. By days 90, 180, and 360, the lymphocyte responses of the nontransfused group had dropped to levels seen at earlier time intervals and were comparable to responses in the transfused group. There were no significant differences between the groups in the number of T-cell colonies formed, the number of immunoglobulin-producing cells obtained, and the lymphokine responses (migration inhibitory factor/migration stimulation factor) at all times tested. The major immunologic perturbations attributed to blood transfusions were an exaggerated decrease in the numbers of circulating lymphocytes, particularly those with markers associated with T-helper cells, and failure to demonstrate a rebound increase in the proliferative response 45 to 90 days later.