Furthermore, CD8+ T cells infiltrate the parenchyma diffusely in the fibrotic tissues of IPF and can differentiate into cells that produce IFN-γ but not IL-4, leading to the attenuation of fibrosis, and cells that produce IL-4 but not IFN-γ, promoting fibrosis [36]. Here, IFNG is linked to idiopathic pulmonary fibrosis.