Inflammatory Response, Immunosuppression and Arginase Activity after Cardiac Surgery Using Cardiopulmonary Bypass

Background: Major surgeries suppress patients’ cellular immunity for several days, but the mechanisms underlying this T-cell dysfunction are not well understood. A decreased L-Arginine (L-Arg) level may inhibit T-cell function. Arginase 1 (Arg 1) is induced after traumatic injury, leading to molecular changes in T cells, including decreased expression of cell surface T-cell receptors (TCRs) and a loss in CD3ζ chain expression. In this study, we examined the temporal patterns of CD3ζ expression and Arg 1 activity in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Methods: We determined the CD3ζ chain expression; the Arg 1 activity; and the leukocyte, neutrophil and lymphocyte levels of patients on the day before surgery and at 24, 48 and 72 h after surgery. Results: Fifty adult patients scheduled for elective cardiac surgery with CPB were eligible for enrolment. Arginase activity was significantly increased between the day before surgery and at 24, 48 and 72 h after surgery (p < 0.01), and CD3ζ expression was significantly decreased between the day before surgery and at 24, 48 and 72 h after surgery (p < 0.001). We observed significant leukocytosis, neutrophilia and lymphopenia after surgery. Conclusions: The decreased CD3ζ chain expression could be due to the increased Arg 1 activity secondary to the activation of neutrophils in cardiac surgery under CPB. These findings could explain the limited immune-system-mediated organ damage resulting from systemic inflammatory response to major cardiac surgery with CPB.