PATHOGENESIS OF IDIOPATHIC PULMONARY FIBR OSIS

Idiopathic pulmonary fibrosis or lone cryptogenic fibrosing alveolitis is an interstitial lung disease of unknown origin carrying an unfavor able prognosis. A yet unidentified hazard triggers a chronic inflammat ory infiltration of the lung parenchyma characterized by an accumulati on of alveolar macrophages, neutrophil and eosinophil granulocytes, an d lymphocytes. Cytokines released by the activated cells modulate the inflammatory events. Oxidants and proteases, mainly released by alveol ar macrophages and neutrophil granulocytes, mediate the injury to the lung parenchyma, leading to loss of alveolar-capillary units. The ensu ing repair process, mesenchymal cell proliferation and up-regulation o f synthesis of collagen fibers and other components of connective tiss ue matrix, replaces lung parenchyma by fibrotic tissue, leading to irr eversible pulmonary dysfunction.