Transcriptional profile of tuberculosis antigen-specific T cells reveals novel multifunctional features

In latent tuberculosis infection (LTBI) spread of the bacteria is contained by a persistent immune response, which includes CD4(+) T cells as important contributors. In this study we show that TB-specific CD4(+) T cells have a characteristic chemokine expression signature (CCR6(+)CXCR3(+)CCR4(-)), and that the overall number of these cells is significantly increased in LTBI donors compared with healthy subjects. We have comprehensively characterized the transcriptional signature of CCR6(+)CXCR3(+)CCR4(-) cells and found significant differences to conventional Th1, Th17, and Th2 cells, but no major changes between healthy and LTBI donors. CCR6(+)CXCR3(+)CCR4(-) cells display lineage-specific signatures of both Th1 and Th17 cells, but also have a unique gene expression program, including genes associated with susceptibility to TB, enhanced T cell activation, enhanced cell survival, and induction of a cytotoxic program akin to CTL cells. Overall, the gene expression signature of CCR6(+)CXCR3(+)CCR4(-) cells reveals characteristics important for controlling latent TB infections.