To confirm the role of IL-β in trypsin upregulation in lung epithelial cells, the site of initial virus infection, human alveolar A549 cells were treated with 10 ng of IL-β per ml, and the expression levels of trypsin in the cells and the levels of secreted IL-1β, IL-6 and TNF-α in the medium were analyzed. Here, IL1B is linked to viral infectious disease.