Objective  To evaluate the changes and significance of lymphocyte subsets in the recipients with acute rejection after liver transplantation.

  Methods  The recipients presenting with acute rejection after liver transplantation were assigned into the rejection group (n=17), and their counterparts with stable liver function were allocated into the control group (n=17) according to the ratio of 1∶1 by propensity score matching method. The incidence of acute rejection after liver transplantation was analyzed, and the concentration of tacrolimus in the recipients was compared between two groups. The absolute value and proportion of lymphocyte subsets in peripheral blood were compared between two groups. The diagnostic value of lymphocyte subsets for acute rejection after liver transplantation was assessed by the receiver operating characteristic (ROC) curve. The absolute value and proportion of lymphocyte subsets in the rejection group were compared before and after treatment.

  Results  Among 17 recipients in the rejection group, 4 cases developed acute rejection within postoperative 28 d, and 13 cases had acute rejection within postoperative 29-180 d. No significant difference was noted in the tacrolimus concentration between two groups (P=0.295). Compared with the control group, the proportions of peripheral blood T cells, CD4⁺T cells, B cells and natural killer (NK) T cells were significantly increased in the rejection group (all P < 0.05). The elevated proportion of NKT cells in the early stage after liver transplantation was an independent risk factor for acute rejection following liver transplantationodds ratio (OR) 1.774, 95% confidence interval (CI) 1.059-2.971, P=0.029. ROC curve analysis showed that the area under curve (AUC) of CD4⁺T cells, B cells and NKT cells was 0.76, 0.73 and 0.77, respectively. The AUC of combined use of CD4⁺T cells, B cells and NKT cells was 0.89, with a cut-off value of 0.69, sensitivity of 0.706 and specificity of 0.941. After corresponding treatment, all recipients were gradually recovered, and liver functions were eventually restored to normal in the rejection group. After treatment, the proportion of T cells, CD4⁺T cells, CD8⁺T cells and NK cells was significantly decreased (all P < 0.05).

  Conclusions  The elevated proportion of NKT cells indicates an increased risk of acute rejection after liver transplantation. Combined use of CD4⁺T cells, B cells and NKT cells may deliver early detection and diagnosis of acute rejection after liver transplantation.