Characterization of a Mycobacterium tuberculosis peptide that is recognized by human CD4+ and CD8+ T cells in the context of multiple HLA alleles.

The secreted Mycobacterium tuberculosis 10-kDa culture filtrate protein (CFP)10 is a potent T cell Ag that is recognized by a high percentage of persons infected with M. tuberculosis. We determined the molecular basis for this widespread recognition by identifying and characterizing a 15-mer peptide, CFP10(71-85), that elicited IFN-gamma production and CTL activity by both CD4(+) and CD8(+) T cells from persons expressing multiple MHC class II and class I molecules, respectively. CFP10(71-85) contained at least two epitopes, one of 10 aa (peptide T1) and another of 9 aa (peptide T6). T1 was recognized by CD4(+) cells in the context of DRB1*04, DR5*0101, and DQB1*03, and by CD8(+) cells of A2(+) donors. T6 elicited responses by CD4(+) cells in the context of DRB1*04 and DQB1*03, and by CD8(+) cells of B35(+) donors. Deleting a single amino acid from the amino or carboxy terminus of either peptide markedly reduced IFN-gamma production, suggesting that they are minimal epitopes for both CD4(+) and CD8(+) cells. As far as we are aware, these are the shortest microbial peptides that have been found to elicit responses by both T cell subpopulations. The capacity of CFP10(71-85) to stimulate IFN-gamma production and CTL activity by CD4(+) and CD8(+) cells from persons expressing a spectrum of MHC molecules suggests that this peptide is an excellent candidate for inclusion in a subunit antituberculosis vaccine.