Mycobacterium intracellulare菌体成分によるサイトカイン誘導能に関する研究

Abstract

Cell-mediated immune response is known to play a central role in host resistance to Mycobacterium avium complex (MAC) infection. However, the mechanims accounting for the persistent survival of intracellular MAC organisms are not elucidated. Interleukin (IL)-10 inhibits anti-mycobacterial activity of macrophages, which are consid- ered to be final effectors against MAC organisms. Clarification of the mechanisms of how IL-10 is induced in association with MAC infection is important to understand the path- ogenesis of MAC infection. The present study was addressed to determine the active moiety in the lysate of M. intracellulare 31 F 093 T to induce IL-10 production. The fraction with a molecular weight of 50 k Da and pI 6.8 was found to induce IL-10 production to a great extent and to suppress IL-12 induction in culture of C57 BL/6 (Bcgˢ) mice spleen cells. Administration of this fraction into A/J (Bcgͬ) mice increased spleen weight and the number of viable mycobacter- ia in the spleen after infection with M. intracellzalare 31 F 093 T. In addition, this treatment suppressed the formation of gramulomatous lesions in the lung of infected mice. These findings indicate that a 50 k Da, pI 6.8 fraction extracted from M. intracellzalare 31 F 093 T contains one of the factors contributing to the progression of MAC infection.