[Depression of cellular immunity after aortic arch replacement]

Area of Science:

• Immunology
• Cardiovascular Surgery
• Critical Care Medicine

Background:

• Postoperative multiple organ failure due to infection is a serious complication after aortic arch replacement.
• Cellular immunity plays a crucial role in the body's response to infection and surgical stress.

Purpose of the Study:

• To evaluate the postoperative changes in cellular immunity following aortic arch replacement.
• To compare the immune response in patients undergoing aortic arch replacement versus coronary artery bypass grafting.

Main Methods:

• Assessed four parameters of cellular immunity: peripheral lymphocyte subsets (CD3, CD4), mitogen responsiveness, natural killer (NK) cell activity, and interleukin-2 (IL-2) production.
• Measured immune variables preoperatively and at multiple time points (1, 3, 7, 14 days) post-surgery in two patient groups: aortic arch replacement (n=5) and coronary artery bypass grafting (n=10).

Main Results:

• Patients undergoing aortic arch replacement showed significantly lower CD3+ and CD4+ lymphocyte counts post-surgery compared to the coronary artery bypass grafting group.
• Interleukin-2 (IL-2) production and natural killer (NK) cell activity were markedly depressed in the aortic arch replacement group compared to preoperative levels and the control group.
• Postoperative depression of IL-2 production was significantly correlated with reduced CD3+ and CD4+ lymphocyte levels.

Conclusions:

• Aortic arch surgery leads to functional depression of cellular immunity, specifically impacting IL-2 production and NK cell activity.
• These immune deficits may be attributed to factors such as massive blood transfusion and tissue trauma during hypothermic cardiopulmonary bypass.
• Understanding and mitigating this postoperative immune suppression is critical for reducing infectious complications after aortic arch surgery.