IL4 and idiopathic pulmonary fibrosis: In addition to cytokine therapy, a study used the serum IFN-γ/IL-4 ratio to represent the Th1/Th2 balance to predict the development of IPF and found that the IFN-γ/IL-4 ratio was associated with symptoms, imaging changes, FEV1 (forced expiratory volume in one second), FVC (Forced vital capacity), TLC (total lung capacity), and 6-min walking distance in IPF patients and can predict IPF progression (Peng et al., 2013).