Table 1.

Possible factors accounting for neutrophilic airway inflammation in asthma.

• Corticosteroid treatment causing reduced apoptosis of neutrophils and contributing to Th17-mediated neutrophilic inflammation

• Neutrophilia associated with chronic sinopulmonary infection or bronchiectasis

• Delayed human neutrophil apoptosis in severe asthma due to epithelial growth factor-induced release of mediators with neutrophil chemotactic and anti-apoptotic actions from bronchial epithelial cells

• Impaired macrophage phagocytosis of neutrophils

• Neutrophilia associated with an altered airway microbiome