Imbalance between CD56^+bright and CD56^+dim natural killer cell subsets in the liver of patients with recurrent hepatitis C after liver transplantation

Abstract

Progressive liver fibrosis remains a major problem for patients with recurrent chronic hepatitis C(CHC) after liver transplantation (LT). However, the involvement of natural killer (NK) and naturalkiller T (NKT) cells, which predominate in the liver, in recurrent CHC after LT remains unclear.In the present study, we investigated the status of NK and NKT cells in the liver andperipheral blood obtained from 10 patients with recurrent CHC after LT (LT-C), 15 patients withCHC, and 7 normal donors for living donor LT. CD56⁺ NK cells were separated into two subsets:CD56^+bright subset, which is identified as major NK cytokine producer, and CD56^+dim subset, whichhas greater spontaneous cytotoxicity. We found a significant decrease in the CD56^+bright subset inthe liver of patients with LT-C compared to patients with CHC (P < 0.01) and normal donors(P = 0.03). The expression of inhibitory NK cell receptor NKG2A was significantly increased onintrahepatic CD56^+bright subset in LT-C patients, and activated CD69⁺CD56^+dim NK cell subset wassignificantly increased in the liver of LT-C patients. Our results suggest that a significant imbalancebetween CD56^+bright and CD56^+dim NK cell subsets in the liver may contribute to the progressionof recurrent CHC after LT.