[The pathogenesis and the development mechanism of Mycobacterium avium complex infection].

Mycobacterium avium complex (MAC) causes respiratory tract infections and develops granulomatous lesions in the alveolar areas and bronchioles in humans. In contrast with the above, the intestinal tract is the primary infection site of immunocompromised hosts, such as patients with acquired immune deficiency syndrome (AIDS), or animals, such as pigs. Recent studies have revealed that hosts with hereditary dysfunction of mediators in the Th-1 cascade as well as hosts with a high titer of auto-antibodies against interferon-gamma are susceptible to MAC, and such hosts facilitate dissemination of MAC. However, their disseminated lesions are formed mainly in the lung or in soft tissues, and the mechanism of development of MAC in such host may be different from that of AIDS-related MAC infection. In this review, we specifically discuss the development mechanism of disseminated MAC disease in recently-identified several pathological conditions.