Abstract
The function of natural killer (NK) cells in inflammation has not been explored enough in large-scale population studies. The cross-sectional and time-dependent relationship between NK cell activity (NKA) and inflammatory markers was examined. Methods: A total of 7031 subjects were involved in the cross-sectional analyses. Non-linear relationship between NKA and inflammatory indices was analyzed using generalized additive models. The time-dependent changes were analyzed in 1005 subjects with repeated measurement in 3–6 months. The changes in inflammatory markers were analyzed based on the changes in NKA. Results: As NKA reduces to a very low level, the white blood cell (WBC) and neutrophil counts increase sharply, and the lymphocyte count exhibits a slow decline. With increasing NKA larger than about 500 pg/mL, WBC and neutrophil-lymphocyte ratio (NLR) reduces in a mild slope. Among the subjects with repeated measurements, the follow-up NKA was increased with advancing baseline NKA levels. The subjects with a reduction in NKA indicated increment in WBC count, neutrophil count, and NLR, and decrease in lymphocyte count. Conclusions: Very low levels of NKA suggest a high inflammatory immune response. The changes in NKA may interact with the balance between neutrophils and lymphocytes.
Highlights
Natural killer (NK) cells are large granular lymphocytes that play critical roles in innate immunity because they recognize and remove virus-infected and neoplastic cells [1].NK cells have cytotoxic activity regulated by activation and inhibition of surface receptors and antibodies [2]
The changes in NK cell activity (NKA) may interact with the balance between neutrophils and lymphocytes
The neutrophil-to-lymphocyte ratio (NLR) is an attractive biomarker of systemic inflammation because it is calculated from the absolute neutrophil and lymphocyte counts collected from a routine complete blood cell count with differentials [17]
Summary
NK cells have cytotoxic activity regulated by activation and inhibition of surface receptors and antibodies [2]. Activated NK cells release cytotoxic granules and secrete cytokines, such as interferon (IFN)-γ and tumor necrosis factor (TNF)-α; these cytokines play an immunoregulatory role as they activate NK cells and further promote cytokine secretion [3]. By these means, NK cells impact the development of adaptive immune responses [4] and contribute to progression and resolution of diseases [5]. NK cells can cause excessive inflammation or even autoimmunity [6]
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