Abstract
OBJECTIVE: This study aims to investigate the the content of CD3(-)CD56(+) Natural Killer (NK) cells in peripheral blood and the serum interleukin-2 (IL-2) and interleukin-8 (IL-8) levels in patients with acute exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD) complicated by respiratory failure (RF). Besides, their diagnostic and prognostic values for AECOPD combined with RF were also explored. METHODS: This retrospective study included patients from the Affiliated Jiangning Hospital of Nanjing Medical University between December 2021 and December 2023. A total of 65 AECOPD patients with RF were selected as the RF group, 64 AECOPD patients without RF as the AE group, and 60 patients with stable COPD as the COPD group. Data on gender, age, course of disease, smoking, alcohol consumption, history of hypertension and diabetes were collected. Serum levels of IL-2 and IL-8 were detected by enzyme-linked immunosorbent assay (ELISA). Arterial oxygen partial pressure (PaO(2)) and arterial carbon dioxide partial pressure (PaCO(2)) at admission were measured by automatic blood gas analyzer. Pulmonary function was assessed using forced expiratory volume in the first second (FEV(1))/forced vital capacity (FVC) and the percentage of FEV(1) to the predicted value (FEV(1)%). The percentage of NK cells (CD3(-)CD56(+)) was detected by flow cytometry. After discharge, patients were followed for one year and categorized into a favorable prognosis (FP) group or an unfavorable prognosis group (UP) based on the severity of lung function impairment. RESULTS: Expression levels of IL-2 in the COPD group, AE group, and RF group were 2.91±0.55, 2.21±0.48 and 1.39±0.43, respectively, while the expression levels of IL-8 were 31.01±4.86, 38.02±5.16 and 44.43±6.54, respectively. The percentages of CD3(-)CD56(+) NK cells in the three groups were 19.93±2.40%, 22.57±3.70% and 25.48±3.64%, and the levels of FEV(1)/FVC were 60.81±6.00%, 51.31±4.95% and 42.67±8.77%, respectively. FEV(1)% were 61.11±5.71%, 45.45±6.86% and 38.77±10.07%, and PaCO(2) levels were 44.08±4.91 mmHg, 53.02±10.52 mmHg and 65±6.63 mmHg, respectively. PaO(2) levels were 81.5±5.64 mmHg, 59.1±5.95 mmHg and 53.86±7.06 mmHg, respectively. The differences in the above indices were statistically significant among the three groups (all P<0.05). In all COPD patients, IL-2, IL-8, and CD3(-)CD56(+) NK cells (%) were associated with lung function and arterial blood gas values. In addition, these markers demonstrated predictive value for the prognosis of AECOPD patients complicated by RF, with their combined detection showing a higher predictive value. CONCLUSIONS: The combined assessment of serum IL-2, and IL-8 levels and positive CD3(-)CD56(+) NK cell rate in peripheral blood of AECOPD patients has diagnostic value for identifying AECOPD with RF and predicting poor prognosis. These markers can serve as predictors of outcomes.