Polyfunctional cytokine production analysis of tetramer+ Mtb-specific CD8 T-cells.
Peripheral blood mononuclear cells (PBMC) were stimulated with the same individual peptides as those present in tetramers and were stained with mAbs to CD8, IFN-γ and IL-2, or with isotype-control mAbs. After gating on CD8+ cells, the percentage of cells expressing IFN-γ and IL-2 was determined. (A) Representative intracellular cytokine staining data in one subject with LTBI, one TB patient before therapy and one PPD− healthy donor. Numbers in the corners indicate the percentage of CD8+ cytokine-positive cells in each quadrant. (B) Summary cumulative data of the IFN-γ and IL-2 secretion capability of tetramer+ Mtb-specific CD8 T-cells in LTBI subjects (white bars) and TB patients with active disease before therapy (black bars). The data are expressed as the percentage of CD8+ T-cells that are IFN-γ+/IL-2− or IFN-γ+/IL-2+. The values reported are the mean percentage of the different subset analysed for each group tested ± standard deviations (SD). *p<0.001 and **p<0.01 when compared to values in LTBI subjects.