Expression of HLA-DR and KLRG1 enhances the cytotoxic potential and cytokine secretion capacity of CD3⁺ T cells in tuberculosis patients

Background Human T cells play an important role in immunity against tuberculosis (TB) infection. Activating receptor HLA-DR and inhibitory receptor KLRG1 are critical regulators of T cell function during viral infection and tumorigenesis, but they have been less studied in TB infection. Methods In this study, we explored the relationship between CD3 + T cell expression of HLA-DR and KLRG1 receptors and function against TB infection. Flow cytometry was conducted to assess the immunomodulatory effects of HLA-DR and KLRG1 receptors on CD3 + T cells in patients with different TB infection status. Results We found activating receptors HLA-DR, NKG2C, CD57 and NKP46, and inhibitory receptors KLRG1 and KIR on CD3 + T cells in different TB infection status showed different distribution patterns; the cytotoxic potential and cytokine secretion capacity of CD3 + T cells after Mtb-specific antigen stimulation were significantly enhanced in TB infection groups. Further studies revealed HLA-DR + T and KLRG1 + T cells expressed higher activating and inhibitory receptors than the negative population. In addition, the expression of cytotoxic potential and cytokine secretion capacity of HLA-DR + T and KLRG1 + T cells was significantly higher than that of HLA-DR - T and KLRG1 - T cells. Conclusions Expression of HLA-DR and KLRG1 enhances the cytotoxic potential and cytokine secretion capacity of CD3 + T cells in TB patients, suggesting CD3 + T cells expressing HLA-DR and KLRG1 are important effector cell phenotypes involved in the host anti-TB infection. HLA-DR and KLRG1 expressed by CD3 + T cells may be potential predictive markers of TB disease progression and clinical immune assessment.