CD8A and infection: Indeed, previous studies reported that PD-1 was significantly increased on Mtb-specific CD8+T cells in HIV/Mtb co-infection compared to Mtb mono-infection, with decreased expression of CD107a, IFN-γ and perforin, furthermore, level of PD-1 expression was associated with reduced IL-2 production capacity (Amelio et al., 2019; Kalokhe et al., 2015; Tan et al., 2023).