Adoptive transfer of tolerance induced by ICRC bacilli against Mycobacterium leprae in mice.

ICRC bacilli, the cultivable leprosy-derived mycobacteria, isolated from lepromatous nodules of leprosy patients were found to be immunogenic in BALB/c mice at a dose of 2 X 10(7) acid-fast bacilli when injected by the intradermal (i.d.) route. The sensitization to lepromin and ICRC antigens was measured by the foot pad enlargement (FPE) method. The same dose of bacilli when injected by intravenous (i.v.), intraperitoneal, and subcutaneous routes induced immune tolerance in mice as indicated by reduction in the FPE to the test antigens. The spleen cells obtained after i.v. injection of ICRC bacilli/Mycobacterium leprae after adoptive transfer brought about suppression of delayed-type hypersensitivity in sensitized as well as nonsensitized recipients, indicating production of suppressor cells after i.v. injection. Similarly, the tolerance induced by i.v. injection of M. leprae in mice could be partially converted to immunity by i.d. sensitization with live BCG and two strains of ICRC bacilli (C-44 and C-75).