Figure 4: Qualitative analyses of HBHA-specific CD3+CD4+ T cell responses by polychromatic flow cytometry in LTBI subgroups and TB patients. (A) Cytokine expression profiles of PBMC stimulated with HBHA were determined by the combined analysis of IFN-γ, TNF-α and IL-2. For all seven possible combinations of these cytokines shown on the x-axis, the frequencies among HBHAspecific CD3+CD4+ T cells are shown on the y axis for QFT- LTBI subjects (green, n=14), QFT+ LTBI subjects (orange, n=10), and TB patients (red, n=11). Subject subgroups were compared using the SPICE Software: *p≤0.05; **p≤0.01. Pie charts summarize the data, and each slice corresponds to the mean of the proportion of the HBHA-specific CD3+CD4+ T cells positive for each combination of expressed cytokines using the color-code shown below the x-axis. (B) Ratio of the frequency of IFN-γsingle+- over the frequency of TNF-αsingle+ CD4+ T lymphocytes after stimulation with HBHA. Results are shown for responders as defined in the methods section. QFT, QuantiFERON Gold in-tube.