Background: Mycobacterium tuberculosis infection affects one-third of the world's population and causes the death of three million people each year. To clarify details of M. tuberculosis survival strategies, it is important to establish a suitable in vitro model that mimics a chronic infection in alveolar macrophages by M. tuberculosis. For this reason, we established a new in vitro model using a rat alveolar macrophage cell line, NR8383.
Materials and methods: Basic characteristics, including phagocytotic ability and production of nitrogen oxide and tumor necrosis factor in response to several stimuli, of NR8383 cells were compared with those of primary alveolar macrophages. The course after phagocytosis of live or killed M. bovis bacilli Calmette-Guerin (BCG) was examined over 21 days using NR8383 cells as the host.
Results: The characteristics that have been examined to date were nearly the same for both primary alveolar macrophage and NR8383 cells. Live BCG phagocytosed by NR8383 cells had successfully begun to grow in the cells within 7 days, while killed BCG were almost completely destroyed by 21 days.
Conclusion: BCG-infected NR8383 cells are potentially a suitable in vitro model that mimics a chronic infection with M tuberculosis.