PRF1 and tuberculosis: The frequency of cytokine- and perforin-producing Mtb-specific CD8 T cells and the functional profile of Mtb-specific CD8 T-cell responses did not differ significantly between TB and Mtb/helminth co-infected patients from TZ with detectable Mtb-specific CD8 T cells (Fig 3B) and the predominant CD8 T-cell population was IFN-γ+IL-2-TNF-α+Perforin- (Fig 3C).