慢性HCV感染者外周血中CD56＋T细胞频数、表型和体外细胞毒功能研究

The frequency, phenotypes and in vitro cytotoxic effects of circulating CD56＋ T cells in the patients with chronic HCV infection

目的探讨慢性HCV感染者外周血中CD56＋T细胞的频数、表型和体外细胞毒功能特征。方法采用流式细胞术检测33例慢性HCV感染者及21例健康对照者外周血CD56＋T细胞的频数和细胞表面活化性受体NKG2C、CD＋6、NKp46和抑制性受体CD＋58a、NKG2A的表达水平；检测体外未刺激及K562细胞刺激作用下CD56＋T细胞毒效应（CD＋07a）和细胞因子分泌水平（IFN-γ和TNF-α），并分析上述3种CD56＋T细胞功能指标之间的关联性。结果与健康对照相比，慢性HCV感染者外周血中CD56＋T细胞在淋巴细胞中的比例明显降低（P=0．018）。CD56＋T细胞表面的活化性受体NKG2C（P=0．015）、CD＋6（P=0．036）、NKpM6（P=0．001）均有不同程度降低，而抑制性受体CD＋58a、NKG2A未发现有统计学意义的差异（P〉0．05）。体外未刺激情况下，慢性HCV感染者CD56＋T细胞分泌细胞因子IFN-γ和TNF-α均显著弱于健康对照组（P〈0．0001）；在K562细胞刺激作用下，慢性HCV感染者CD56＋T细胞CD＋07a水平及分泌细胞因子IFN-γ和TNF-α均呈显著降低趋势（P〈0．0001），且3种功能指标表达水平密切关联（r〉0．80，P〈0．0001）。结论慢性HCV感染者CD56＋T细胞频数降低，细胞毒能力和重要细胞因子分泌能力均明显减弱。该结果提示显著受损的CD56＋T细胞功能可能与HCV慢性持续性感染有关。

Objective To explore the cell frequency, phenotypes and in vitro cytotoxic effects of circulating CD56＋ T ceils in the patients with chronic HCV infection. Methods Peripheral blood mononu- clear cells （PBMCs） were isolated from 33 patients with HCV chronic infection and 21 healthy subjects. Multi-color flow eytometry was used to analyze cell frequency, expressions of activating receptors （ NKG2C, CD16 and NKp46） and inhibitory receptors （NKG2A and CD158a） on CD56＋ T ceils. The functional mark- er for cytotoxic effects （CD107a） on circulating CD56＋ T cells and their cytokines expression （ IFN-γ and TNF-α） with or without stimulation of K562 human Leukemia cell line were also analyzed. Then the correla- tions among the expressing levels of CD107a, IFN-γ and TNF-αwere investigated. Results The frequency of CD56＋ T ceils in periphery lymphocytes were significantly decreased in the patients with chronic HCV in- fection as compared with that in healthy controls （ P = 0. 018 ）. The expressions of activating receptors （NKG2C, CD16 and NKp46） on CD56＋ T cells from HCV infected patients were decreased （P=0. 015 for NKG2C, P=0.036 for CD16 and P=0.001 for NKp46）, while there was no significant change in the ex- pressions of inhibitory receptors （P〉0.05 for both CD158a and NKG2A）. The concentrations of IFN-γ and TNF-α secreted by CD56＋ T cells in the patients with chronic HCV infection were significantly decreasedwith or without K562 stimulation （P〈0. 0001 ）. However, in the presence of K562 cells CD107a expression on CD56＋ T cells were sharply decreased in the patients （ P〈0. 0001 ）. In absence of K562 cells, there was no significant change in CD107a expression on CD56＋ T cells from patients and healthy controls （P〉0.05）. The expressions of CD107a, IFN-γand TNF-α were closely related under the stimulation of K562 （r〉0. 80, P〈0.0001 ）. Conclusion The frequency of CD56＋ T ceils was reduced in patients with chronic HCV infec- tion. Moreover, cytotoxic effects and cytokines production mediated by CD56＋ T cells were also significantly impaired, indicating that the dysfunction of circulating CD56＋ T cells might be associated with the persist- ence of chronic HCV infection.