Figure 1.

Representative flow cytometry “combination gates” analysis of CD4⁺ T cells of LTBI, active TB, and control subject under stimulation of TB antigens. Whole blood was analysed using a gating strategy to exclude debris and to identify CD4⁺ and CD8⁺ T cells on CD45⁺ lymphocytes. The subsequent analysis was on CD4⁺ gate to describe IFN-γ, IL-2, and TNF-α producing T cells. The percentages of the seven different population cells were showed at bottom and were defined in CD4⁺ cell gate on the basis of total IFN-γ, IL-2, and TNF-α producing cells.