Immature and activated phenotype of blood NK is associated with acute rejection in adult liver transplant.

Abstract

Natural killer (NK) cells contribute to liver transplant (LTx) rejection. However, the blood-circulating NK cell dynamics of patients who experience acute rejection (AR) are unclear. Herein, we longitudinally profiled the total NK cells and their subsets, along with the expression of activating and inhibitory receptors in sequential peripheral blood mononuclear cells samples, spanning from pre-LTx to the first year post-LTx of 32 patients with AR and 30 patients under a steady immune status. Before transplantation, patients with AR (rejectors) contained a significantly higher proportion of the immature CD56brightCD16- subset and a lower cytolytic CD56dimCD16+ in the total blood-circulating NK cells than patients with steady immunity. Both subsets contained a high NKp30 positive population, and CD56dimCD16+ additionally exhibited a high NKp46 positive ratio. The NKp30 positive ratio in CD56dimCD16+ subset showed the most prominent AR predictive ability pre-LTx, and was an independent risk factor of LTx AR. After transplantation, the blood-circulating NK cells in rejectors maintained a higher CD56brightCD16- and lower CD56dimCD16+ composition than the controls throughout the first year post-LTx. Moreover, both subsets maintained a high NKp30 positive ratio, and CD56dimCD16+ retained a high NKp46 positive ratio. The blood-circulating NK-cell subset composition was consistent during AR, while the expressions of NKp30 and NKp46 were augmented. Collectively, a more immature CD56brightCD16- subset composition and an activated phenotype of high NKp30 expression were the general properties of blood-circulating NK cells in rejected LTx recipients, and the NKp30 positive ratio in CD56dimCD16+ NK subset pre-LTx possessed AR predictive potential.