Changes in T-cell receptor subsets after cardiac surgery in children

Abstract

T cells are divided into two subsets, alphabeta and gammadelta, according to the T-cell receptor (TCR) expressed. Recent findings indicate that gammadelta T cells serve as the first defense against microbial pathogens, and represent a link between innate and acquired immunity. We conducted a study to investigate the changes in circulating TCR subsets after cardiac surgery in children. Blood samples from 24 children who underwent cardiac surgery with cardiopulmonary bypass (CPB) were collected serially to analyze TCR subsets by flow cytometry. The alphabeta T cells reached a nadir on postoperative day (POD) 1, but recovered to pre-CPB levels on POD 3. On the other hand, the gammadelta T cells decreased after CPB and did not recover to pre-CPB levels even after POD 7. The alphabeta/gammadelta T-cell ratio was increased after POD 3. In children, gammadelta T cells recover more slowly than alphabeta T cells after cardiac surgery. These changes in TCR subsets may contribute to postoperative immunosuppression.

Changes in lymphocyte subsets after cardiac surgery in children

“…However, without exception, T-cell levels were profoundly reduced 24 h after surgery. This is in accordance with findings in adults [21,23].…”

“…We are not aware of any studies investigating the changes in all lymphocyte subsets during and after CPB in a paediatric population. The influence of operations using CPB on the total white cell and differential cell counts seen in this study is in agreement with several studies in adults [3,16,23] in as much as the haematocrit-corrected white cell count decreased during CPB. Explanations for this decrease include a loss of leucocytes in the membrane-oxygenator or within organs, the application of leucocyte depleted packed red cells or a combination of these factors.…”

“…In our population, we also saw a decrease in absolute cd-TCR-T-cell numbers. The relative value of these cells reached preoperative levels 24 h after surgery whereas Yamaguchi et al [23] were not able to demonstrate a return to baseline values during a 7-day observation period. After 7 days, the blood dilution during CPB should no longer play a major role, therefore further studies with larger patient numbers are needed to resolve these conflicting data.…”

“…Heat shock proteins are released after different forms of stress, suggesting a role of cd-TCR-T-cells in immune responses induced by stress. Yamaguchi et al [23] found a decrease in the absolute cd-TCR positive cell count. They did not correct for the dilution effects of the CPB.…”

Effacing of the T Cell Compartment by Cardiac Transplantation in Infancy

“…As an additional control, we studied two subjects with nontransplant cardiac surgery in infancy. These subjects underwent thymectomy in the course of surgery and suffered some level of T cell depletion as a consequence of cardiopulmonary bypass (25,26), but were not treated with T cell-depleting agents or immunosuppression. One subject, studied 2 mo after surgery had normal TCR␤ diversity (4.1 ϫ 10 6 ) and normal levels of TREC (1925 TREC per 100 ng DNA); however, the other subject, studied 1 year after surgery, had decreased TCR␤ diversity (1.7 ϫ 10 4 ) and decreased levels of TREC (177 TREC per 100 ng DNA) (Fig.…”