TNF and pulmonary fibrosis: They can directly kill virus-infected cells and tumor cells and regulate immune responses by releasing cytokines such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α).[23] In the environment of pulmonary fibrosis, this regulation may lead NK cells to shift from promoting inflammation to aiding tissue repair, possibly by affecting the phenotype and function of other immune cells.