Frequency and functional profile of circulating TCRαβ⁺ double negative T cells in HIV/TB co-infection

Background Increased frequency of circulating double negative T (DNT, CD4 - CD8 - CD3 + ) cells with protective immune function has been observed in human immunodeficiency virus (HIV) infection and tuberculosis (TB). Here the role of circulating TCRαβ + DNT cells was further investigated in HIV/TB co-infection. Methods A cross-sectional study was conducted to investigate the frequency and functional profiles of peripheral TCRαβ + DNT cells including apoptosis, chemokine and cytokine expression among healthy individuals and patients with TB, HIV infection and HIV/TB co-infection by cell surface staining and intracellular cytokine staining combined with flow cytometry. Results Significantly increased frequency of TCRαβ + DNT cells was observed in HIV/TB co-infection than that in TB (p + DNT cells (p = 0.049), and the frequency of Annexin V expression on Fas + TCRαβ + DNT cells had no significant difference. TCRαβ + DNT cells expressed less CCR5 in HIV/TB co-infection than that in TB (p = 0.014), and more CXCR4 in HIV/TB co-infection than that in HIV infection (p = 0.043). Compared with healthy controls, TB and HIV/TB co-infection had higher frequency of TCRαβ + DNT cells secreting Granzyme A (p = 0.046; p = 0.005). In TB and HIV/TB co-infection, TCRαβ + DNT cells secreted more granzyme A (p = 0.002; p = 0.002) and perforin (p + T cells but similar to CD8 + T cells. Conclusions Reduced apoptosis may take part in the mechanism of increased frequency of peripheral TCRαβ + DNT cells in HIV/TB co-infection. TCRαβ + DNT cells may play a cytotoxic T cells-like function in HIV/TB co-infection.