Study GIPF-002 is a phase 2 study designed to characterize the biologic and clinical effects of IFN-g 1b. The objective of the Study is to characterize the biologic and clinical effects of IFN-g 1b administered to patients with idiopathic pulmonary fibrosis (IPF). The Study will be conducted at multiple sites and enroll 30 patients with IPF who have failed treatment with corticosteroids.