Human tracheal gland serous (HTGS) cells are now considered one principal pulmonary target for the gene therapy of cystic fibrosis (CF). We developed a CF tracheal gland serous cell line, CF-KM4, obtained by the transformation of primary cultures of CF tracheal gland serous cells homozygous for the DeltaF508 mutation by using the wild-type SV40 virus. This cell line retained epithelial and secretory features of the native CF-HTGS cells in primary culture, namely, presence of cytokeratin, constitutive secretion of secretory leukocyte proteinase inhibitor, absence of responsiveness to carbachol and isoproterenol, and defective cyclic adenosine monophosphate-dependent chloride channel activity. Adenovirus-mediated CF transmembrane conductance regulator (CFTR) gene transfer into CF-KM4 cells corrected the defective chloride channel activity as well as the responsiveness to adrenergic and cholinergic agonists. In contrast, control transfection using adenovirus-mediated beta-galactosidase gene transfer was totally ineffective. In conclusion, these results present a stable CF tracheal gland cell line that has retained its epithelial and CF-specific defective secretory characteristics which are corrected after CFTR gene transfer. This cell line therefore appears to be a useful tool for large-scale molecular and cellular pharmacologic investigations designed to test potential therapies of the disease CF.