['An immune function assay has been proposed as a new strategy to monitor immunosuppression after organ transplantation. However, there are limited data regarding its role in liver transplant recipients with hepatocellular carcinoma (HCC). In this study, we sought to determine the utility of this functional assay in assessing the risk of infection, rejection, and tumor recurrence in liver transplant recipients.', 'Immune function was determined by ImmuKnow assay that measures the amount of adenosine triphosphate (ATP) produced by CD4 (+) T cells to monitor the global immune status in 342 whole blood samples from 105 liver transplant recipients. The association between ATP value and post-transplant tumor recurrence was evaluated in 60 HCC patients. The ATP value in predicting tumor recurrence in other independent cohort of 92 recipients with HCC was analyzed prospectively.', 'The mean ATP values of liver transplant recipients with infection (145.2\xa0±\xa087.0\xa0ng/ml) or acute rejection (418.9\xa0±\xa0169.5\xa0ng/ml) were different from those with stable state (286.6\xa0±\xa0143.9\xa0ng/ml, P\xa0<\xa00.05). In recipients with HCC who developed recurrent tumors, the values were significantly lower than those without recurrence (137.8\xa0±\xa066.4 vs. 289\xa0±\xa0133.9\xa0ng/ml, P\xa0<\xa00.01); the optimal threshold value to predict post-transplant tumor recurrence was 175\xa0ng/ml. Comparing with the patients in lower immune group (ATP\xa0≤\xa0175\xa0ng/ml), patients in the higher immune group (ATP\xa0>\xa0175\xa0ng/ml) experienced significantly better disease-free survival (P\xa0<\xa00.01). Multivariate Cox regression analysis showed the ATP value was an independent predictor of HCC recurrence.'] Does an immune function assay predict post-transplant recurrence in patients with hepatocellular carcinoma?