However, in culture, GM-CSF secretion by ex vivo sputum cells is increased in COPD.18 Similarly, whether GM-CSFR expression is increased in airways disease is contentious, with one study suggesting that GM-CSFR is increased in non-atopic, but not atopic asthma.19 Therefore, GM-CSF and GM-CSFR expression in airways disease needs to be further defined. The gene discussed is CSF2; the disease is atopic asthma.