Asthma is a chronic respiratory condition frequently associated with aberrant airway and systemic inflammation. Various inflammatory phenotypes in asthmatic airways have been described that relate to clinical phenotypes and impact on responses to conventional and novel asthma therapies. Macrophages are abundant immunocytes in the lung, capable of mounting diverse responses required for homeostasis and defence against pathogens.

Here, we summarise the clinical evidence regarding macrophage dysfunction in asthma. We also describe evidence supporting the role of macrophages as therapeutic targets in asthma. We conclude that macrophage dysfunction in asthma is highly prevalent and heterogeneous, and hypothesise that macrophages may play roles in promoting the discrete inflammatory phenotypes of asthma.

These clinical findings, along with recent ground-breaking insights into the ontogeny, behavioural complexity and longevity of pulmonary macrophages, support continued research into the role of macrophages as disease modifiers, biomarkers and therapeutic targets in asthma.