Mechanism and specificity of immunoprotection induced by mycobacterial proteins against experimental tuberculosis in mice.

Mechanism of immunoprotection and specificity of two highly immunoprotective mycobacterial proteins, viz. 71 and 30 kDa were investigated. The adoptive transfer studies indicated that immunoprotection was mainly mediated by cooperative effect of CD4+ and CD8+ (66.7-73.3% on the basis of percent survival) which was further enhanced marginally by supplementation of B cells, natural killer cells, dendritic cells, macrophages and other immune cells. The specificity studies indicated that both the proteins did not cross react with the unrelated intracellular pathogens i.e. Aspergillus fumigatus, Salmonella typhi and Leishmania donovani as seen by T cell proliferation assay. The protection imparted by these mycobacterial proteins was also specific as the 71 and 30 kDa primed mice did not exhibit any cross protection against sublethal challenge of S typhi. The results indicate 71 and 30 kDa mycobacterial proteins to contain T cell specific epitopes responsible for specific immunoprotection, thus indicating their potential role as antituberculous vaccine candidates.