Human T cell clones recognize two abundant Mycobacterium tuberculosis protein antigens expressed in Escherichia coli

Human T cells reactive to Mycobacterium tuberculosis were cloned from peripheral blood mononuclear cells (PBMC) of four tuberculosis patients by using whole irradiated bacilli as the in vitro stimulatory agent. Twenty-two T cell clones (CD4+) were tested for their reactivity to 12 different mycobacterial species and showed a distribution from limited to broad cross-reactivity. These T cell clones were also tested for their reactivity to three abundant M. tuberculosis proteins of 65, 19, and 14 kD, each expressed from recombinant DNA in Escherichia coli. The three proteins were expressed from DNA clones that were previously isolated from a lambda gt11 genomic DNA library of M. tuberculosis by using monoclonal antibodies directed against this pathogen. A T cell clone from one patient was stimulated by an E. coli lysate containing the 65 kD antigen, and a T cell clone from a second patient was stimulated by an E. coli lysate containing the 19 kD antigen in an in vitro proliferation assay. Both T cell clones showed very limited cross-reactivity when tested against other mycobacteria. We conclude that some patients with tuberculosis exhibit a T cell response to the 65 and 19 kD M. tuberculosis proteins defined by these isolated genes.