Antigen specific cytokine secretion in PBMC of active TB patients. PBMC from control subjects and active TB patients were cultured for 18 and 72 hours after stimulation with SEA, PPD, ESAT-6/CFP-10 and BCG or left un-stimulated (none). Cells were then treated as specified in the M&M section for analysis of secreted cytokines (IFN-γ and IL-2) and evaluated on CD16- gated cells by flow cytometry. Data from one representative experiment are reported. Numbers indicate the percentages of positive cells in the relative quadrants.