Chronic obstructive pulmonary disease (COPD) is a chronic and often progressive disorder with a heterogeneous presentation and frequent systemic manifestations. Several aspects like persistence in smoking habit, continuous exacerbations, alpha-1-antitrypsin deficiency and inflammatory-immune response, are involved in the pathophysiology and progression of the disease. However, the role of natural killer (NK) cells remains controversial. Otherwise, human cytomegalovirus (HCMV) infection has been reported to induce an adaptive differentiation and expansion of an NK cell subset which carries the CD94/NKG2C receptor, which may contribute to an upset immune defense. For these reasons, our objective is to assess the distribution of NK cells and their subset in COPD patients and some of its phenotypes. Peripheral blood samples were obtained from 66 COPD patients. HCMV serology and the proportions of total NK cells and the NKG2C+ and NKG2A+ subsets were evaluated by flow cytometry. The NKG2C genotype was also assessed. Eighty-eight per cent of COPD patients were HCMV(+), and the proportions of total NK cells were higher in patients with severe-very severe airway obstruction than in those with only mild-moderate involvement. There were no differences in the proportions of NKG2C+ cells between controls and COPD, either among COPD patients classified by severity of the disease. However, the percentage of NKG2C+ cells were higher in COPD patients with frequent exacerbations than in occasional exacerbators, and higher in cases with reduced lean mass (Fat free mass index) than in those with normal nutritional status. These results suggest a relationship between levels of NKG2C+ cells in COPD patients and clinical variables closely linked to a poor/worse prognosis.

中文翻译：

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适应性NKG2C +自然杀伤细胞与COPD患者病情加重和营养异常有关

慢性阻塞性肺疾病（COPD）是一种慢性疾病，通常是进行性疾病，表现形式不一，经常出现全身性表现。该病的病理生理学和进展涉及吸烟习惯的持续存在，持续恶化，α-1-抗胰蛋白酶缺乏和炎性免疫反应等几个方面。但是，自然杀伤（NK）细胞的作用仍存在争议。否则，已经报道了人类巨细胞病毒（HCMV）感染可诱导携带CD94 / NKG2C受体的NK细胞亚群的适应性分化和扩增，这可能会导致免疫防御能力下降。由于这些原因，我们的目的是评估COPD患者中NK细胞及其亚群的分布及其某些表型。从66名COPD患者获得外周血样品。通过流式细胞术评估HCMV血清学和总NK细胞以及NKG2C +和NKG2A +亚群的比例。还评估了NKG2C基因型。COPD重症患者中有88％为HCMV（+），重度至极重度气道阻塞患者的总NK细胞比例高于轻度中度受累患者。在按疾病严重程度分类的COPD患者中，对照组和COPD之间的NKG2C +细胞比例没有差异。然而，频繁加重的COPD患者的NKG2C +细胞百分比高于偶尔加重的患者，瘦体重（无脂肪质量指数）降低的患者的NKG2C +细胞百分比高于营养状况正常的患者。