Susceptibility of Mycobacterium leprae to the bactericidal activity of mouse peritoneal macrophages and to hydrogen peroxide.

Macrophages from athymic nude mice were infected in vitro with Mycobacterium leprae to study the intracellular fate of this organism. Using the proportional bactericidal test, we have shown that the viability of M. leprae declines rapidly within these macrophages, although results of clearance experiments demonstrate that live and killed organisms are cleared at comparable rates. We have also shown that M. leprae is susceptible to the bactericidal effects of hydrogen peroxide and we suggest that hydrogen peroxide generated by macrophages is responsible for the killing of intracellular M. leprae.

Attempts at cultivation of Mycobacterium leprae in macrophages from susceptible animal hosts.

Macrophages from nude mice, nude rats, and armadillos were cultured in vitro and examined for their ability to support Mycobacterium leprae. No significant growth of this organism were observed after over 200 days of culture. No significant benefit was derived from modifying culture conditions or from variations in the source of macrophages or the source of M. leprae.