Although previous clinical trials of the systemic administration of IFN-γ in IPF patients failed [21, 44, 45], our group has demonstrated that inhaled IFN-γ is safe and without systemic effects, and inhaled IFN-γ produced a measured improvement in the diffusion capacity in patients with IPF [28, 29]. The gene discussed is IFNG; the disease is idiopathic interstitial pneumonia.