Blood eosinophils and its relation to sputum inflammation and sputum bacterial load in patients with acute exacerbation of chronic obstructive pulmonary disease

Background: little is recognized on the role eosinophils in the pathophysiology of acute exacerbation of chronicobstructive pulmonary disease (AECOPD).Objective: To assess the relationship between eiosinophilic AECOPD and sputum inflammation and bacterial load.Methodology: A cross-sectional study was done on 80 out of 189 patients presented by clinical picture of AECOPD.Spirometry, total and differential leucocytic count (TLC), sputum bacterial load and culture were done for all participants.They were divided into two subgroups based on blood eosinophils %; eosinophil high AECOPD (≥2%) and eosinophil lowAECOPD (˂ 2%).Results: Among the studied patients; 51.25% have eosinophilhigh and 48.75% have eosinophil low AECOPD. Patients witheosinophils high AECOPD had higher age, BMI, smoking status, smoking index, wheezes and FVC%, with more severe COPD and more severe AECOPD (p0.018) than those with eosinophil low AECOPD. In patients with eosinophil high AECOPD the blood TLC/cm3 and neutrophil % were significantly lower, while lymphocyte % and eosinophil /cmm3 were higher significantly than eosinophil low AECOPD (p 0.001 each). Regarding sputum inflammatory cells they had significant increase of sputum lymphocyte % and eosinophil/cm3 and % with significant decrease of sputum neutrophils % (p˂0.05). In eosinophil high AECOPD subgroup the blood eosinophil /cmm3 was positively correlated with age, BMI and smoking index, blood lymphocytes % eosinophils %, sputum lymphocytes % and sputum eosinophils and it was negativelycorrelated with blood TLC, blood and sputum neutrophils, FEV1/FVC ratio, FEV1 % FEF25-75 % and FVC%. The sputumbacterial load was non-significantly lower in eosinophil high than eosinophil low AECOPD (61.0% vs. 74.4%, p=0.20).Thetype of the isolated bacteria didn’t differ between both AECOPD subgroups (p=0.17).Conclusion: Eosinophilic AECOPD is common and it was related to airway inflammation and it didn’t’ affect sputumbacterial load or type of isolated bacterial species