Although the role of interleukin 18 in the development of pulmonary fibrosis is yet to be conclusive, however, it is reported that interleukin 18 may act as a proinflammatory factor by secreting interleukin 1β, tumor necrosis factor-α, and other cytokines, which can aggravate the damage to the lung tissues. This evidence concerns the gene TNF and pulmonary fibrosis.