Generation of an immortal differentiated lung type-II epithelial cell line from the adult H-2K(b)tsA58 transgenic...

This paper describes a new fully differentiated Type-II alveolar epithelial cell line designated T7, derived from transgenic H-2K(b)-tsA58 mice, capable of being passaged as an immortalized cloned cell line in culture. H-2K(b)-tsA58 mice harbor a temperature-sensitive (ts) mutant of the simian virus 40 (SV40) large tumor antigen (T antigen) under the control of the gamma-interferon (INF)-inducible mouse major histocompatibility complex H-2Kb promoter. When cultured under permissive conditions (33 degrees C and in the presence of gamma-INF) cells isolated from H-2Kb-tsA58 mice express the large T antigen, which drives the cells to proliferate. However, upon withdrawal of the gamma-INF and transfer of the cells to a higher temperature (39 degrees C), T antigen expression is turned off, the cells stop proliferating and differentiate. The T7 cell line is a clonal cell line originally derived from a Type-II cell-rich fraction isolated from lungs of H-2Kb-tsA58 mice. The T7 cells form confluent monolayers, and have a polarized epithelial cell morphology with tight junctions and apical microvilli. In addition, the T7 cells have distinct cytoplasmic lamellar bodies, which become more numerous and pronounced when the cells are grown under nonpermissive conditions. The T7 cells synthesize and secrete phosphatidylcholine and the three surfactant proteins, SP-A, SP-B, and SP-C. The T7 cell line is unique in that it is the first non-tumor-derived Type-II cell line capable of synthesizing and secreting the major components of surfactant. Based on the criteria studied, the T7 cell line is phenotypically very similar to normal Type-II cells. The T7 cell line, therefore, should prove a valuable experimental system to advance the study of the cell biology/physiology of surfactant metabolism and secretion as well as serve as a model for other studies of Type-II cell physiology.