Asthma is an inflammatory disorder of the airways, which causes attacks of wheezing, shortness of breath, chest tightness, and coughing in patients. Degrees of severity are unique to individual patients as are responses to drug treatments. Adhesion of eosinophils to bronchial epithelial cells, and the interaction of airway smooth muscle and sub-epithelial fibroblasts play a critical role in asthma pathology. During an asthma attack bronchiole smooth muscle tissue can constrict and decrease the flow of air in the airways. The amount of air flow can further be decreased by inflammation or excess mucus secretion.Small airway epithelial cells stained for Cytokeratin 19. Lonza's Human Small Airway Epithelial Cells (SAEC) are isolated from asthmatic human lung tissue the distal portion of the lung in the 1mm bronchiole area.Cryopreserved SAECs are guaranteed through 15 population doublings and stain positive for cytokeratin 19. All cells testnegative for mycoplasma, bacteria, yeast, and fungi. HIV-1, hepatitis B and hepatitis C are not detected for all donors and/or cell lots. A Certificate ofAnalysis is provided for each cell lot purchased.