[Depression of cellular immunity after aortic arch replacement]

Multiple organ failure due to infection is now one of the most serious postoperative complications following aortic arch replacement. We therefore evaluated the postoperative changes of cellular immunity using four parameters, 1) peripheral lymphocyte subsets 2) mitogen responsiveness 3) the activity of natural killer (NK) cells 4) interleukin-2 (IL-2) production. Patients were divided into two groups: group A (n = 5) with aortic arch replacement and group B (n = 10) with coronary artery bypass grafting. All variables were measured the day before, the day after, 3 days after, 7 days after, and 14 days after surgery. CD3 positive cells in group A were significantly lower than in group B throughout the postoperative course. CD4 positive cells in group A were significantly lower than in group B on the day after 3 days after the operation. IL-2 production in group A was markedly depressed the day after (all patients 0.8 U) and 3 days after (1.5 +/- 1.6 U) as compared to the preoperative level (7.7 +/- 4.4 U) and the levels on the same days in group B. The activity of NK cells in group A was significantly impaired the day after (10.6 +/- 6.7%) and 3 days after (10.0 +/- 6.7%) as compared to the preoperative level (28.6 +/- 16.7%) and the levels on the same days in group B. IL-2 production in group A was significantly correlated to CD3 and CD4 positive lymphocyte levels. These results clearly showed that patients who underwent aortic arch surgery suffered functional depression of cellular immunity, in particular IL-2 production and the activity of NK cells. These depressions may be a result of massive blood transfusion, tissue trauma under hypothermic cardiopulmonary bypass.