Immune response and modulation of immune response induced in the guinea pigs by Mycobacterium avium complex (MAC) and M. fortutium complex isolates from different sources in the South Indian BCG trial area.
Kamala, T.; Paramasivan, C.N.; Daniel Herbert; Venkatesan, P.; Prabhakar, R.
Indian Journal of Medical Research; 1996; 103; 201-211.
A total of 139 guinea pigs were used to study the immune response and its modulation induced by Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different sources in the south Indian BCG trial area. The guinea pigs were divided into groups and some were directly sensitised/ immunised with different MAC strains. M. fortuitum complex strain or BCG and others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The resulting delayed type hypersensitivity (DTH) response in the different groups of guinea pigs was studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging the guinea-pigs with a South Indian low virulent strain of M. tuberculosis and enumerating the bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and sputum induced different levels of immune modulation during subsequent immunisation with BCG on the DTH response to PPD-RT23 and PPD-B. At 2 wk. after challenge 23,8,81 and 90.5% percent protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively, while 33.3 percent protection was induced by the M. fortuitum complex strain compared to the protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have any modulatory effect on the protective immunity due to BCG were protected, modulation of the protective response resulting from BCG was observed in the guinea pigs sensitised with MAC and M. fortuitum from soil.
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