CFTR and cystic fibrosis: There is much debate about whether the proinflammatory state observed in people with CF is present as a result of infection37 38 or as a primary manifestation of abnormal CFTR function.1439, 42 We found that colonisation with one or more of the four key pathogens shown to be clinically important in preschool CF (P. aeruginosa, S. aureus, H. influenzae and Aspergillus9) did not significantly influence cellular or soluble signatures of inflammation in BAL.