Effect of dexmedetomidine on CD4+ T cells and programmed cell death protein-1 in postoperative analgesia: a prospective, randomized, controlled study.

Background Surgical trauma inhibits cellular immunity. Dexmedetomidine produces opioid-sparing effect and an impact on immune response. Methods Eighty-six surgical patients were enrolled and received postoperative patient-controlled intravenous analgesia (PCIA) with either fentanyl alone (fentanyl group) or combined with dexmedetomidine (dexmedetomidine group). The percentages of T helper cells (Th1, Th2, and Th17) and regulatory T (Treg) cells, expression levels of programmed cell death protein-1 (PD-1) and its ligand (PD-L1) on the CD4+ T cells, and plasma levels of the cytokines were tested. Postoperative pain was measured by numerical rating scale (NRS), including NRS at rest (NRSR) and movement (NRSM). Results In dexmedetomidine group, Th1 cells were increased significantly at 24 and 48 h following surgery (P=0.011 and P=0.013, respectively) and Treg cells were significantly higher at 48 h postoperatively (P=0.013). PD-1 was significantly lower in dexmedetomidine group at 24 h postoperatively (p=0.046) and interleukin 4 (IL-4) and IL-6 were significantly decreased at 48 h postoperatively (P=0.024 and P=0.035, respectively). Compared with fentanyl group, NRSR scores were lower in dexmedetomidine group at 24 h following surgery (P=0.018) and NRSR and NRSM scores were lower at 48 h postoperatively (P=0.007 and P=0.011, respectively). NRSR exhibited negative correlations with Th1 cells in fentanyl group and dexmedetomidine group (P=0.003 and P=0.005, respectively). Conclusions Dexmedetomidine increases the differentiation of Th1 and Treg cells and reduces the expression of PD-1 on CD4+ T cells. Dexmedetomidine may assist to ameliorate postoperative pain and attenuate pro-inflammatory response. There might be a negative correlation between pain and Th1 cells.