Possible Role of IL-25 in Eosinophilic Lung Inflammation in Patients with Chronic Eosinophilic Pneumonia

Purpose Interleukin (IL)-25 and IL-33 induce IL-5 production by various types of cells, such as type 2 helper T (Th2) cells and type 2 innate lymphoid cells. The number of Th2 cells and concentration of IL-5 in the bronchoalveolar lavage fluid (BALF) are increased in patients with eosinophilic pneumonia (EP). To examine the contribution of IL-25 and IL-33 to eosinophilic inflammation of the lung in humans, we evaluated IL-5, IL-25 and IL-33 levels in the BALF of patients with EP.