Specificity of CD8⁺ T cells from subunit-vaccinated and infected H-2^b mice recognizing the 38 kDa antigen of Mycobacterium tuberculosis

CD8⁺ T cells have been implicated in protective anti-tuberculous immune responses, but little is known about the identity of mycobacterial antigens recognized by CD8⁺ T cells. In this study we identified the Mycobacterium tuberculosis 38 kDa protein as a target for murine CD8⁺ cytotoxic T lymphocytes (CTL) which were induced by vaccination of C57BL/6 mice with DNA delivered with a plasmid, with transfected tumour cells or by infection with tubercle bacilli. Using overlapping synthetic peptides covering the whole protein sequence, peptides predicted to contain H-2K^b or H-2D^b motifs, as well as naturally processed peptides, we were able to identify CTL epitopes. Differences were demonstrated in peptide specificity between CTL from immunized or M. tuberculosis-infected mice. The identified CTL epitopes could be important for future analysis of the involvement of CD8⁺ T cells in M. tuberculosis infections and for vaccine development.