Gao J, et al. - Given a frequent use of measurement of sputum to define airway inflammatory subtypes, researchers here investigated if venous blood cell can quantify sputum inflammatory cell to access the airway subtypes in chronic obstructive pulmonary disease of acute exacerbations (AECOPD). Further, they inquired about the accuracy of the blood cell biomarker. Four tests (lung function test, bronchodilator reversibility test, sputum cell analysis, and blood routine examination) were performed on the same day on 287 patients with COPD exacerbations. Outcome analyses revealed that eosinophil and neutrophil parameters were a relationship between sputum and blood. They identified poor capability of peripheral blood eosinophil (absolute and percentage) and derived ratios (eosinophil/lymphocyte ratio, the eosinophil/neutrophil ratio, and eosinophil/macrophage ratio) in distinguishing patients with sputum eosinophilia, but identified these parameters as significant. Further, possibly no predictive value of white blood cell (× 10⁹/L), blood neutrophil (absolute and percentage) and its ratios [neutrophil/lymphocyte ratio (NLR) and neutrophil/macrophage ratio] is suggested for neutrophilic AECOPD. Mixed granulocytic AECOPD vs neutrophilic AECOPD exhibited decreased blood neutrophil (absolute and percentage) and NLR, which may indicate systemic inflammation, but these were not enough to become clinically useful.