Abstract
Introduction: Failure of bacterial clearance is a key component of the vicious cycle of bronchiectasis. Neutrophils fail to phagocytose pathogens in bronchiectasis, but the mechanisms underlying this process are not fully known.
Methods: We investigated whether airway secretions from 59 bronchiectasis patients may be inhibitory towards neutrophil phagocytosis. Healthy peripheral neutrophils were treated with 10% soluble sputum for 30 minutes at 37oC prior to phagocytosis of FITC labelled P. aeruginosa. Phagocytosis was assessed by flow cytometry.
Results: 59 patients were studied. Mean age was 68 years (SD 12), 51% female. 49% had idiopathic bronchiectasis. Mean FEV1 was 83.6% and mean BSI 6.8. Effects of soluble sputum on phagocytosis were diverse, ranging from 55% inhibition to 7.9x enhancement after exposure. 28 sputum samples had an inhibitory effect on phagocytosis while 31 had a stimulatory effect on phagocytosis. No single parameter identified inhibitory sputum samples, but logistic regression found these patients were more likely to have severe bronchiectasis according to the BSI (odds ratio 1.47 (95% CI 0.76-1.31), p=0.008). Phagocytosis was also associated with respiratory symptoms (r=0.5, p=0.02) and physical functioning on the QoL-B questionnaire (r=0.59, p=0.008). Inhibitory effects of sputum were only weakly related to sputum neutrophil elastase activity (p=0.1).
Conclusion: A subgroup of bronchiectasis patients have airway factors that inhibit neutrophil phagocytosis in sputum. These patients have more severe disease and poorer quality of life.
Footnotes
Cite this article as: European Respiratory Journal 2018 52: Suppl. 62, OA4949.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2018