The mechanism(s) of chronic airway inflammation in cystic fibrosis (CF) remains poorly understood. We studied Ca2+-induced release of arachidonic acid (AA), a precursor of proinflammatory lipid mediators, in epithelial cell lines with the deltaF508 mutation in CF transmembrane conductance regulator (CFTR) gene and in those lacking this mutation or cells in which this mutation was corrected by a functional CFTR gene transfer. We found that: (i) the mutant cells manifested an abnormally high Ca2+-induced AA release as compared to controls, (ii) AA release appeared to be catalyzed by a phospholipase A2 (PLA2) but not by phospholipase C followed by diacylglycerol lipase, and (iii) either correction of the CFTR-mutation or inhibition of PLA2 activity rectified this AA release abnormality. Taken together, our results suggest that CFTR mutation is associated with an intrinsic abnormality in AA release by epithelial cells carrying the deltaF508 mutation and suggest that the mechanism of chronic airway inflammation in CF, at least in part, involves this abnormality. These results also partly explain the effectiveness of high-dose ibuprofen therapy in arresting the progression of destructive lung disease in CF. Furthermore, they raise the possibility that correction of abnormal AA release by inhibiting PLA2 activity may improve the therapeutic benefits of ibuprofen.