[Pathogeny-etiology of sarcoidosis]

It is now well established that sarcoidosis is a granulomatous disorder resulting from an uncontrolled cell-mediated immune reaction in response to unknown antigens. This reaction is characterized by the presence of typical granulomas at the sites of the disease, made of activated macrophages (epithelioid cells) and T lymphocytes. The interactions between both cell types lead to the production of numerous inflammatory mediators which are essential for the development of granulomas. Recently, sarcoid granulomas have been shown to express a Th1 pattern of cytokines. The modulation of the expression of some of them could be useful for the development of new therapies. The etiology of sarcoidosis remains unknown, but recent advances concerning this disorder suggest that it results from various causes involving a particular genetic background and exposure to specific environmental factors. Recent data have emphasized in some patients the expression of particular HLA haplotypes, the polymorphism of various genes, and the presence of oligoclonal T lymphocytes. The characterization of the antigenic specificity of these T cells could be helpful in identifying agents responsible for the disease. The role of mycobacterial agents is still controversial.