Off-Pump Coronary Artery Bypass Grafting Does Not Reduce Lymphocyte Activation

Objective: In this study, we test the hypothesis that off-pump coronary bypass surgery might result in less lymphocyte activation than on-pump coronary surgery. We also study the behavior of lymphocyte activation markers during and after surgery.

Background: Coronary artery bypass surgery is known to be associated with changes of inflammatory mediators, immune function, and early phase lymphocyte activation, which could cause postoperative lymphopenia and lymphocyte unresponsiveness.

Methods: We studied lymphocyte activation response in 28 patients randomized to off-pump (n=13) or on-pump (n=15) coronary artery bypass surgery. Expression of CD25, CD26, CD69, and DR on T (CD3+) and B (CD19+) lymphocytes on peripheral blood was assessed through flow cytometry.

Results: The response of T lymphocytes and their activation markers, as well as B lymphocytes and their activation markers, was similar after on- and off-pump surgery. Overall, T lymphocytes decreased to the lowest level 9 h after surgery and tended to increase later. For B lymphocytes, there was early reduction with increase on the 1st postoperative day. There was early activation of CD69+ and late activation of CD25+ on T lymphocytes. For B lymphocytes, there was early activation of CD69+ and late activation of DR+.

Conclusions: (1) Compared to on-pump cardiopulmonary bypass, off-pump surgery does not reduce lymphocyte activation. (2) Coronary bypass surgery causes the early activation of lymphocytes, as evidenced by the increased expression of lymphocyte activation markers.