Abstract: A mutant transgenic mouse and cell line derived from the mouse are disclosed. The mutant transgenic mouse was developed from a cross between a mutant mouse which carries mutant genes that express a phenotype similar to human Hermansky-Pudlak Syndrome, and a mouse strain containing a transgene encoding a temperature sensitive protein that is inactive at physiological temperatures. The resulting mutant mouse is characterized by the presence of the HPS mutations as well as the transgene. The mutant mouse and cell lines derived from the lung tissue of the mouse are useful models for lung pathology associated with human HPS, lung fibrosis and inflammation. Methods and assays utilizing the cell lines also are disclosed.