Median frequencies of IFN-γ + CD4 and CD8 T cells in PBMC of TB patients before and after 2 weeks of anti-TB therapy. Freshly isolated PBMC from newly diagnosed sputum smear positive and HIV-negative TB patients (n = 19) were stimulated for 6 days with ESAT-6/CFP-10, Rv1733, Rv2029, Rv2628, SEB and the un-stimulated control (Medium). IFN-γ + CD4+ and IFN-γ + CD8+ T cells were assessed by flow cytometry by subtracting the percentage in un-stimulated cultures from stimulated ones. A threshold of 0.2% IFN-γ + CD4/ CD8 T cells defined positive T-cell responses against antigens. The Mann–Whitney U test (P < 0.05) was used to compare frequency of IFN-γ + CD4 (A) and CD8 (B) T cells at baseline and week two in response to ESAT-6/CFP-10 (n = 11), Rv1733 (n = 10), Rv2029 (n = 6), Rv2628 (n = 6). Also shown is the frequencies IFN-γ + CD4 (C&D) and CD8 (E&F) T cell at baseline (T0) and at 2 weeks (T1) into treatment for individual participants with data available for response to ESAT-6/CFP-10 (n=8) and Rv1733 (n=6). P values computed with the Wilcoxon signed rank test (P<0.05).