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

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.