RESUMO
An immunological study of pathogenesis of tuberculosis was carried out in BALB-c mice in-vitro. Peritoneal macrophages obtained from BALB-c mice were challenged with virulent (H37Rv) and avirulent (H37Ra, BCG, M. phlei) strains of mycobacteria. Activated peritoneal macrophages showed enlargement, presence of intracellular bacteria and vacuolation. These significant changes in macrophage morphology were clearly evidenced in cells infected with virulent strains of Mycobacterium tuberculosis i.e. H37Rv while being absent in cells infected with avirulent H37Ra, BCG and M. phlei. Virulent mycobacteria (H37Rv) survive the phagocytic action of macrophages by residing inside the vacuoles. The capacity of virulent and avirulent strain to stimulate TNF-alpha production from peritoneal macrophage of BALB-c mice was also examined at different time interval i.e. 1,2,4,6 and 8th day by measuring cytolytic activity of culture supernatant against murine fibroblast cell line. The pattern of highest TNF release was in case of H37Rv and least with M. phlei as measured in culture supernatant after 1,2,4,6 and 8th day.