Serum markers for the staging of disease activity of sarcoidosis and other interstitial lung diseases of unknown etiology

Immunopathogenic mechanisms in sarcoidosis, idiopathic pulmonary fibrosis, and pulmonary manifestations of collagen-vascular diseases maintain an alveolitis which may lead to irreversible organ damage. The classical parameters used in the management of pulmonary involvement of these disorders are chest X-ray and pulmonary function test which do not gauge alveolitis but rather pulmonary impairment. From the immunopathogenesis several serological parameters have been delineated estimating different aspects of inflammatory processes. Cytokines, soluble cytokine receptors, metabolites, enzymes, extracellular matrix components, soluble adhesion molecules, and other serum components have been evaluated to serve as serological markers of alveolitis. The mechanisms gauged by these markers, and their clinical usefulness are discussed in this review.