Is interferon produced in physiologic conditions?

On the basis of a number of physiologic, microbiologic and immunologic data it is possible to formulate the hypothesis that interferon is produced continuously in health by the gut-and bronchial-associated lymphoid tissue and, although several anatomic areas are involved, interferon synthesis is supposed to be restricted to the mucosal portals of entry. The interferon physiologic response is characterized by prevalent production of type II interferon and by its localized release, function and catabolism. However, the consequences of this response may have far-reaching biological importance because production of IF, though localized, can activate fundamental defence systems throughout life. It is furthermore postulated that the progressive decline of the interferon physiologic response may be one important event favouring the insurgence of tumours and autoimmune diseases in ageing.