Release of superoxide anion from activated mouse peritoneal macrophages during Mycobacterium tuberculosis infection

Mouse peritoneal macrophage monolayers infected with M. tuberculosis were cultured in RPMI up to 7 days. Release of superoxide was assayed on different days in presence or absence of Phorbol myristate acetate (PMA), a known stimulator of NADPH oxidase which is involved superoxide production. Basal level of superoxide release was significantly higher in M. tuberculosis infected peritoneal mouse macrophages (P < 0.01) as compared to normal mouse macrophages. When normal and tuberculoid macrophage cultures were stimulated with PMA, increased superoxide anion release was observed in both the cultures but the increase of superoxide was significantly higher in normal macrophages as compared to tuberculoid stimulated macrophages. Superoxide release was maximum in 4 day old cultured macrophages and gradually it declined in older cultures by day 7, both in vitro and in vivo. A defective macrophage function in killing of M. tuberculosis bacilli was observed after 4 days of in vitro and in vivo cultures.