Representative flow cytometric plots showing gating strategy and expression of CD244/2B4.

<p>(A) Viable lymphocytes in PBMCs were gated based on characteristic forward and side scatter profiles. (B) The gate depicting CD4/CD244 expression was defined by both control isotype staining and CD244 expression on CD3⁻CD4⁻ cells that showed clearly two cell subsets with positive and negative staining of CD244. (C and D) CD4⁺ T cells were defined as CD3⁺CD4⁺ cells (C) and CD244/2B4 expression on total CD4⁺ T cells was shown (D). (E and F) Antigen-responsive CD4<b>⁺</b> T cells were identified by appearance of activation marker CD69 in the CD3⁺CD4⁺ cell population (E) and CD244/2B4 expression on <i>M. tuberculosis</i> antigen-responsive CD4⁺ T cells was shown (F). Isotype: isotype antibody control; LI: latent TB infection; TB: active TB patients.