Reactive oxygen intermediates inactivate Mycobacterium leprae in the phagocytes from human peripheral blood.

Reactive oxygen intermediates such as hydrogen peroxide, superoxide, and hydroxyl radicals are important microbicidal components, and they could also play a role in an infection with Mycobacterium leprae. A comparative study of the level of hydrogen peroxide and superoxide produced by peripheral blood phagocytes from normal healthy individuals and lepromatous leprosy patients showed a deficiency in superoxide production in the patients. In the phagocytes from normal healthy individuals, there was good release of superoxide ions, and this mediated the killing of M. leprae. The lack of superoxide production allowed the viability of M. leprae inside the macrophages from leprosy patients. This deficiency could be rectified by the use of an immunomodulator, the delipidified cell wall of M. leprae. This modulation resulted in the ability of the patients' phagocytes to respond to M. leprae, to produce reactive oxygen intermediates such as superoxide, and also to kill the bacteria. These observations indicate that delipidified cell wall could have significant potential to positively modulate the immune-deficient cells of leprosy patients.