Exhaled breath condensate (EBC) may provide a potential source of biomarkers that could be useful in a variety of diseases, including CF.118 Several potential EBC biomarkers have been investigated in CF, including EBC pH, fractional exhaled nitric oxide, leukotriene-B4, 8-isoprostane, hydrogen peroxide, interferon-γ, IL-10, IL-4, tumor necrosis factor, purines and glucose.118 At present there is insufficient evidence to support the use of any of these biomarkers as outcome measures in clinical studies. Here, TNF is linked to cystic fibrosis.