IFNγ-secreting T cells that highly express IL-2 potently inhibit the growth of intracellular M. tuberculosis in macrophages

Cytokine of interferon-gamma (IFNγ) plays a vital role in the immune response against <i>Mycobacteria tuberculosis</i> (Mtb) infection, yet the specific function of T cells producing IFNγ in this process remains unclear. In this study, we first isolated IFNγ⁺CD3⁺ T cells induced by Mtb antigens using surface staining assays. which showed a strong ability to inhibit the growth of intracellular mycobacteria in macrophages. Peripheral blood mononuclear cells (PBMCs) from healthy individuals were then challenged with Bacillus Calmette-Guérin (BCG) or Mtb, respectively, to sort IFNγ-secreting T cells for mRNA sequencing to analyze the gene expression patterns. The results of the integrated data analysis revealed distinct patterns of gene expression between IFNγ⁺CD3⁺ T cells induced by the BCG vaccine and those induced by Mtb pathogens. Further, unlike Mtb-induced cells, BCG-induced IFNγ⁺CD3⁺ T cells expressed high levels of interleukin-2 (IL-2), which increased the frequencies of these cells and the production of effector cytokines IFNγ and IL-2. Our findings suggested that IFNγ⁺CD3⁺ T cells with high IL-2 expression presented potent effector functions to inhibit intracellular Mtb growth, while Mtb infection impaired IL-2 expression in IFNγ⁺CD3⁺ T cells.