A complex component modulating immune‐deficient cells in leprosy patients leading to loss of viability of Mycobacterium leprae— a possible vaccine

SUMMARY Macrophages from peripheral blood of leprosy patients, both multi‐bacillary and paucibacillary are unable to kill phagocytosed Mycobacterium leprae due to their inability to produce superoxide (O 2 .) and hydroxyl radicals (OH.). The macrophages from healthy individuals are able to kill M. leprae along with release of O 2 − and OH. radicals. The deficiency in the macrophages of both types of leprosy patients is removed by activation of these cells when exposed to a culture supernatant obtained after stimulation of peripheral blood mononuclear cells from the same patients with delipidified cell components of M. leprae which are most likely cell wall proteins. The activation of macrophages also leads to recognition of whole live M. leprae as an antigen by cells from lepromatous patients. This activation of the phagocytes by delipidified cell components is blocked by cyclosporin A, indicating the possible role of several steps involved in immune activation of cells. The observations thus indicate the significant ability of delipidified cell components to eliminate the deficiencies in the macrophages from leprosy patients and restore them to behave like the cells from healthy individuals. Considering all these, it is suggested that delipidified cell components could be potential modulators, and are probably capable of functioning as a vaccine for leprosy.