[Chronic infiltative lung disease and viruses].

A role for viruses in the development or course of the main idiopathic chronic infiltrative lung disease has been suggested for a long time. Viruses that have usually been incriminated in cryptogenic fibrosing alveolitis are hepatitis C virus, whose role has not been accurately proven, and latent viruses including Epstein-Barr virus and adenovirus. These latent viruses might be re-activated in the lung of patients immunocompromised by treatments and might be accountable for disease progression. However, published studies have been very conflicting and the only clinical trial testing ribavirin has failed to demonstrate a beneficial effect. In sarcoidosis, the responsibility of human herpesvirus 6 and 8 and retroviruses has not been proven. Finally, data in the literature do not support a link between Langerhans cell histiocytosis and human herpesvirus 6 and 8. These viruses may act by several mechanisms: viral proteins may be antigens driving an appropriate immune response; they may also behave as transactivating factors to control the expression of various genes involved in immune response, cell growth or synthesis of matrix proteins.