Gaskell, Rosemary

Hall, Simon R.

Hessel, Edith M.

Lea, Simon

Maschera, Barbara

Singh, Dave

Vitlic, Ana

Background: Defective macrophage phagocytosis has been shown in COPD using bronchoalveolar lavage and blood monocyte derived macrophages. The phagocytic capabilities of sputum macrophages and/or neutrophils in COPD are unknown. Sputum is a non-invasive sampling technique that can be performed at different disease states including exacerbation. We investigated phagocytosis in sputum macrophages and neutrophils from healthy controls and COPD patients at stable state. Methods: Phagocytosis of Steptococcus Pneumoniae or fluorescently labelled non-typeable Haemophilus influenzae (phRODO NTHI) by sputum macrophages and neutrophils was determined by gentamycin protection assay (n=5 COPD patients) or flow cytometry respectively in 14 COPD patients, 8 healthy smokers(HS) and 8 healthy non-smokers (HNS). Sputum macrophages and neutrophils were differentiated by adherence for the gentamycin protection assay or receptor expression (CD206 and CD66b respectively) by flow cytometry. Results: Using the gentamycin protection we observed a greater uptake of Streptococcus Pneumoniae by sputum neutrophils compared to sputum macrophages in COPD patients (p&lt;0.05). Flow cytometry showed greater uptake of phRODO NTHI by CD66b+ neutrophils compared to CD206+ macrophages in COPD patients and HS (p&lt;0.05) Uptake of phRODO NTHI by CD206+ macrophages was decreased in HS and COPD compared to HNS (p&lt;0.05). There was no differences in uptake of phRODO NTHI by CD66b+ neutrophils between groups. Conclusion: In these assays, sputum neutrophils showed more phagocytic activity than macrophages. Bacterial phagocytosis is impaired in sputum macrophages, but not sputum neutrophils, in COPD patients compared to HNS

Assessment of the phagocytic capability of sputum macrophages and neutrophils in COPD patients

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