Identification of mycobacterial HSP70 reactive human T cell clones discriminating between M. tuberculosis and M. leprae

M. tuberculosis reactive CD4⁺ T cell clones were established from a BCG vaccinated donor and tested for proliferative responses against complex mycobacterial antigens like M. tuberculosis , M. leprae , and PPD, as well as the recombinant M. tuberculosis HSP70 and HSP65 antigens from both M. tuberculosis and M. leprae . This screening permitted the identification of T cell clones specifically recognizing the mycobacterial HSP70 or HSP65 antigen. All HSP65 reactive T cell clones were cross-reactive for M. tuberculosis and M. leprae , whereas three HSP70 reactive T cell clones only recognized M. tuberculosis . In addition, HLA typing and blocking experiments with anti-HLA antibodies revealed that antigen presentation to all M. tuberculosis reactive T cell clones was restricted by HLA-DR3 molecules. We have thereby demonstrated the presence of human T cell specificities directed against the mycobacterial HSP70 antigen that are able to discriminate between M. tuberculosis and M. leprae .