Infection with the wild type SV40 virus was used to transform primary cultures of human tracheal gland serous (HTGS) cells. Over 80 different cell lines were obtained, but the majority had lost some of their epithelial and secretory features. However, one of these cell lines, MM-39, was shown to have conserved the physiologic characteristics of the genuine HTGS cells-i.e., the presence of cytokeratin, expression of cystic fibrosis transmembrane conductance regulator mRNA, a level of secretory leukocyte proteinase inhibitor secretion comparable to that of the native cells (25 +/- 3 ng/10(6) cells/h), and the responsiveness to pharmacological agonists: carbachol (+260 +/- 40%), isoproterenol (+260 +/- 40%), and adenosine 5'-triphosphate (+280 +/- 30%). These characteristics describe a transformed cell line of human tracheal gland cells which has retained the features of the native serous cells. As a result, this cell line appears to be a useful tool for large-scale physiologic and pharmacologic studies of bronchial secretion at the cellular level.