The major objectives of the study were: (1) to continue the prospective, longitudinal study of carefully defined cases of IPF; (2) to initiate a study of patients with PSS, a disease that provided a useful paradigm for studying the early events of the disease; (3) to determine the role of the lymphocyte in IPF, by defining the subset of T lymphocytes responsible for modulating macrophage function; (4) to establish the role of non-invasive techniques (bronchoalveolar lavage (BAL), HRCT scanning and scintigraphy -- neutrophil and monocyte labelled cells) in assessing the activity of inflammation in carefully evaluated patients; (5) to determine the relationship of these results to the -- carefully defined and serially obtained -- clinical, radiographical, and physiological findings and to the histopathologic abnormalities (in patients that underwent lung biopsy, predominantly IPF cases). (6) to perform studies utilizing blood, BAL fluid and lung tissue in an effort to understand the pathogenic mechanisms that underlied the inflammatory/immune cellular injury and fibrosis that characterize this disease.