[Pathogeny of sarcoidosis].

Sarcoidosis is a multisystemic granulomatous disorder due to an immune response of unknown etiology. The interactions between monocytes/macrophages and T lymphocytes through direct contact between the cells play a major role in the occurrence of these responses. Factors depending on the host, such as the polymorphism of the major histocompatibility complex molecules could be implicated in sarcoidosis pathogenesis. The factors that regulate the degree of granulomatous reaction, or those that determine the degree of fibrous response observed in some patients with sarcoidosis are poorly understood. Two recent studies, using the high sensitivity of the polymerase chain reaction, have shown the presence of M. tuberculosis DNA in 13 to 50% of biopsy samples from sarcoid patients, suggesting a role of this agent in the disease, at least in certain cases.