Immunopathogenesis of sarcoidosis

Abstract

Sarcoidosis is a multisystemic disease of unknown pathogenesis. Its characteristic feature is formation of noncaseating granuloma in involved organs. The current etiologic hypothesis suggests that an unknown antigen/agent might promote granuloma formation in hosts genetically susceptible to Th1-response. The network of interactions between immunocompetent cells (mainly Th1-lymphocytes and macrophages) and the influence of many cytokines and chemokines lead to the sarcoid granuloma formation. Its central core is made up of a number of macrophages, epithelioid cells and multinuclear giant cells. Those are surrounded by a rim consisting mostly of CD4+ Th- lymphocytes. Interferon-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-12 and IL-18 play a critical role in driving to the Th1 response. Advances in technology gradually reveal new aspects of sarcoidosis pathogenesis. Recent studies on the potential cause of the disease examine genetic, environmental, immunological and infectious factors. They provide systematically new data and enrich our knowledge, but the etiology of sarcoidosis remains mysterious.