Cultivation of Mycobacterium leprae: a new approach.
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Biomedical subjects
Publications and source records attributed to C V Bapat.
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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).
Clinico-pathological features of five cases of lepromatous leprosy exhibiting "reversal" reaction with upgrading of lesions following vaccination with ICRC vaccine have been described. Two patients also developed ENL. Associated with the "reversal" reaction, the patients exhibited lepromin conversion. No evidence of fresh nerve lesions was observed in any patient. Besides lepromin conversion, occurrence of "reversal" reaction is yet another evidence of immunogenicity of the ICRC vaccine.
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The ICRC bacilli are acid-fast bacilli cultivated from M. leprae isolates of lepromatous tissue. The ICRC bacilli from C-44 in the conditioned medium were subjected to foot-pad test, in both normal and T/900r mice. The bacilli exhibits a limited multiplication in normal mice while a continuous growth in T/900r mice. The maximum yield for normal and T/900r mice was 10(7) and 10(9)/foot-pad, respectively. The infiltration of voluntary muscle tissue as the main localization site was common for both normal and T/900r mice with evidence of dissemination in the latter. The spread of AFB to sciatic nerve, induction of liver granuloma and the foot-drop was observed only in T/900r mice. These experiments show that the growth of ICRC bacilli in mouse foot-pad is very similar to that of M. leprae confirming a test for identification.
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Skin test antigens (Dharmendra type) were prepared from fresh M. leprae (lepromin) and from a culture of strain C-44 ICRC bacilli (ICRCin) grown 'in vitro' from M. leprae isolate from lepromatous nodules. Comparative study of skin reactivity to lepromin and ICRCin--both "early" and "late" reactions in 76 leprosy patients was conducted. In 29 lepromatous (LL) cases, 25 exhibited totally negative reaction at the end of third week. In tuberculoid (TT) 22 and 23 out of 31 were positive (greater than 4.5 mm) at 3 weeks to lepromin and ICRCin respectively. In the 16 BB group, the reactions were comparable in the same patient. The cellular reaction in tuberculoid cases consisted of lymphocytic infiltration, epitheloid giant cells and Langhan type cells and indistinguishable from each other. These data with characteristic total lack of reaction in 25/29 lepromatous leprosy cases and identical cellular reaction in TT patients, provide strong evidence that ICRC bacillus strain C-44 is antigenically identical with M. leprae.
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