IL13 and pulmonary fibrosis: IL-13 is a cytokine that has been implicated in type 2 driven inflammatory processes in several pulmonary diseases including parasitic, viral, and fungal infections15, 17, 18, 19, as well as allergic diseases20, 21, asthma22, bronchiolitis obliterans23, 24, usual interstitial pneumonia25, and idiopathic pulmonary fibrosis.