The present study investigates which mediators most closely correlate with IFNγ in sputum in stable and exacerbating disease, and seeks to shed light on the spatial requirements for innate production of IFNγ, as reported in mouse lymph nodes, to observe whether such microenvironmental cellular organisation [8] is relevant to IFNγ production in COPD lung. Here, IFNG is linked to chronic obstructive pulmonary disease.