Classically restricted human CD8(+) T lymphocytes derived from Mycobacterium tuberculosis-infected cells: Definition of antigenic specificity

Previous studies in murine and human models have suggested an important rol e for HCA Ia-restricted CD8(+) T cells in host defense to Mycobacterium tub erculosis (Mtb), Therefore, understanding the Ags presented via HLA-Ia will be important in understanding the host response to Mtb and in rational vac cine design, We have used monocyte-derived dendritic cells in a limiting di lution analysis to generate Mtb-specific CD8(+) T cells. Two HLA-Ia-restric ted CD8(+) T cell clones derived by this method were selected for detailed analysis. One was HLA-B44 restricted, and the other was HLA-B14 restricted. Both were found to react with Mtb-infected, but not bacillus Calmette-Guer in-infected, targets. For both these clones, the Ag was identified as cultu re filtrate protein 10 (CFP10)/Mtb11, a 10.8-kDa protein not expressed by b acillus Calmette-Guerin. Both clones were inhibited by the anti-class I Ab and anti-HLA-B,C Abs, Using a panel of CFP10/Mtb11-derived 15-aa peptides o verlapping by 11 aa, the region containing the epitopes for both clones has been defined. Minimal IO-aa epitopes were defined for both clones. CD8(+) effector cells specific for these two epitopes are present at high frequenc y in the circulating pool. Moreover, the CD8(+) T cell response to CFP10/Mt b11 can be largely accounted for by the two epitopes defined herein, sugges ting that this is the immunodominant response for this purified protein der ivative-positive donor. This study represents the first time CD8(+) T cells generated against Mtb-infected APC have been used to elucidate an Mtb-spec ific CD8(+) T cell Ag.