Abstract
Eosinophils are one of the inflammatory cells involving allergic diseases and are recognized as effector cells in airway inflammation of bronchial asthma. The two major effector functions are the release of toxic granule proteins and active oxygen species. Here we examined the effects of toxic granule proteins of human eosinophils, such as major basic protein (MBP), eosinophil peroxidase (EPO), eosinophil cationic protein (ECP), and eosinophil-derived neurotoxin (EDN) against airway lung carcinoma cells (A549 cell, ATCC CCL185) which were infected with respiratory syncytial virus (RSV). Cytopathic effects of A549 cells were observed in the course of time (every 24 hour). None of injury on A549 cells was observed in cases of RSV alone whose dose was 0.1 and 1 moi up to 48 hours. High concentrations of MBP and EPO did harm to A549 cells by themselves after 24 hours, however ECP and EDN didn't such response even after 48 hours in macro phase. On the other hand, in case of infection with RSV, the degree of injury in A549 cells treated with MBP and EPO was significantly increased; it depended on the concentration of RSV in macro phase. The viability of A549 cells which were infected and/or treated were also measured by the cell viability analyzer (Vi-CELL). It exhibited that the viability of A549 cells which were infected with RSV and following treated with eosinophil granule proteins was lower than that of RSV infection alone. The results suggested that eosinophils and its products might induce excess injury to airway epithelial cells especially when airway epithelial cells were infected with RSV and this might promote the eosinophilic inflammation in bronchial asthma.
