Although the Th2 and Th1 phenotypes are not as well defined in idiopathic pulmonary fibrosis as they are in asthma and animal models, their potential importance is one rationale for trials in which immunomodulators such as IFN-γ are used in an attempt to switch the inflammatory responses to a more Th1-like phenotype. Here, IFNG is linked to idiopathic pulmonary fibrosis.