Up-regulation of the Apo/Fas (CD95) complex on neutrophils harvested during cardiac surgery: distinct findings in patients operated on with or without the use of cardiopulmonary bypass

Abstract

Aims: In a group of patients undergoing cardiac surgery performed both with (“on-pump”) and without the use (“offpump”) of cardiopulmonary bypass (CPB), we studied the changes of neutrophil membrane apoptosis-inducing complex Apo/Fas.

Methods: Expression of Apo/Fas (CD95) on leukocytes was evaluated by flow cytometry.

Results: In “on-pump” patients, we found an increase in the expression of CD95 median intensity fluorescence (MFI) on granulocytes from a baseline level median=56, (Q ₁=45.5, Q₃=64) to a median=88, (Q₁=62, Q ₃=109.5; p<0.01) at the 3^rd postoperative day and median=74, (Q₁=63, Q₃=84.5; p<0.01) at the 7^th postoperative day. In “off-pump” patients, granulocyte CD95 MFI was median=55, (Q₁=51, Q₃=84) before surgery. The significant increase was found on the 3^rd postoperative day only; median=90, (Q ₁=66; Q₃=98; p<0.05). A similar pattern in the CD95 expression was also found if percentage changes of granulocyte CD95 MFI were followed. Moreover, the significantly increased Apo/Fas expression expressed as a percentage change of CD95 MFI was found in “on-pump” patients compared to “off-pump” patients, both at the 3^rd postoperative day (p<0.05) and at the 7^th postoperative day (p<0.01).

Conclusions: This is the first direct evidence of increasing densities of the Apo/Fas complex on neutrophils in cardiac surgical patients.