Hydrogen peroxide and superoxide release by alveolar macrophages from normal and BCG-vaccinated guinea-pigs after intravenous challenge with Mycobacterium tuberculosis

Abstract

The release of H2O2 and .O2- by alveolar macrophages from normal and BCG-vaccinated guinea-pigs was measured 3 h, 3 days and 6 days after i.v. challenge infection with Mycobacterium tuberculosis H37Ra. Vaccination did not affect the release of H2O2 or .O2- form macrophages that were removed from guinea-pigs 3 h after i.v. infection and tested as monolayers without a phagocytic stimulus. However, macrophages that were removed from vaccinated animals on the third and sixth days after i.v. infection released progressively more than macrophages that were removed after 3 h. This was not seen with cells from i.v.-infected normal animals. Exposure of macrophage monolayers to phorbol myristate acetate (PMA) and opsonized H37Ra caused increased release of H2O2 and .O2-. There was no difference in the response to PMA either between macrophages from normal animals and those from vaccinated animals or between macrophages taken 3 h, 3 days and 6 days after i.v. infection. Thus the response with PMA gave no indication of the development of local immunity. In contrast, with H37Ra as a phagocytic stimulus in vitro the amounts of H2O2 and .O2- released per cell-associated bacillus increased with the time elapsed since i.v. infection. This increase was greater with the macrophages from vaccinated animals than those from normal animals. The results support the hypothesis that H2O2 production by macrophages is involved in killing M. tuberculosis in vivo.