In the BALF of IPF patients and in systemic circulation, the levels of Th1 cells and their secretion of IFN-γ are relatively low, and the levels of Th2 cells and their secretion of IL-4/IL-5/IL-13 are relatively high (Hams et al., 2014). The gene discussed is IFNG; the disease is idiopathic pulmonary fibrosis.