Activation of T cells to peptides that span the 19 kDa protein of Mycobacterium tuberculosis

It has been suggested that the cellular immune response to mycobacterial antigens, is implicated in the pathogenicity of inflammatory joint diseases such as rheumatoid arthritis. Therefore, the aim of this study was to identify T-cell epitopes in a series of 20-mer peptides spanning the entire 19-kDa protein of M. tuberculosis. Mononuclear cells obtained from six rheumatoid arthritis (RA) patients, were analyzed for their proliferation to both the 19-kDa containing immunoblot fraction and to the synthetic peptides. Mononuclear cells from three rheumatoid arthritis patients responded in a dose-dependent manner to peptides 1-20, 60-79, 71-90, 82-101, 90-109 and 121-140, whereas the other eight peptides: 11-30, 21-40, 41-60, 50-69, 100-119, 112-131, 131-150 and 140-159 did not stimulate significant proliferative responses in any of the patients tested. These results indicate, for the first time, the presence of dominant epitopes in the cellular immune response to the 19-kDa M. tuberculosis antigen by rheumatoid T cells.