Figure 1.

Gating strategy for IFN-γ analysis in T-cell subsets and IFN-γ production by CD4⁺ and CD8⁺ T-cells in patients with active TB and LTBI. Plots show the distribution and frequency of IFN-γ in PBMCs of a representative active TB and LTBI subject. Lymphocytes were gated based on their SSC-A and FSC-A parameters, following which only live cells were considered according to the negativity of the Viability Stain antibody and single cells were gated as described. CD3⁺ T-cells were gated according to the expression of their surface marker. SSC-A = side scatter; FSC-A = forward scatter; IFN-γ = interferon-gamma; LTBI = latent TB infection; PBMC = peripheral blood mononuclear cell.