FIG 4.

Memory phenotypes of monofunctional IFN-γ⁺ CD4⁺ and IFN-γ⁺ CD8⁺ T cells in ltLTBI and PTB. A total of 1.5 × 10⁵ PBMCs from individuals with ltLTBI or PTB were cultured in triplicate for 7 days in the presence or absence of PPD, E6-C10, and DosR and Rpf antigens. CD4⁺ and CD8⁺ T cells were stained as described in Materials and Methods and then analyzed for intracellular production of IFN-γ, TNF-α, and IL-2. The frequencies of single- and multiple-cytokine-producing CD4⁺ and CD8⁺ T cells were evaluated using the combination gate tool from FlowJo v7.6.1. The memory phenotypes of monofunctional IFN-γ⁺ CD4⁺ (A) and IFN-γ⁺ CD8⁺ (B) T cells were evaluated by flow cytometry according the surface expression of CD45RO and CD27. Statistical differences between the groups were calculated with the Mann-Whitney U test. *, P < 0.05; **, P < 0.01; ***, P < 0.001.