B-cells contribute to the magnitude of T-cell responses in treated TB patients.

To investigate the contribution of B-cells to T-cell activation in the various groups of Mtb infected individuals we depleted CD19⁺ B-cells from PBMCs and compared the T-cell responses following BCG stimulation in total PBMC to those in B-cell depleted PBMCs. Ethnicity of donors was indicated using the following symbols: ‘black circle’ = West Europe; ‘black diamond’ = Est Europe; ‘black square’ = Africa; ‘black triangle’ = Asia; ‘black star’ = Sud America. Data obtained from B-cell depleted samples were compared pair-wise to total PBMC samples using the Wilcoxon signed Rank test and a p-value < 0.05 was considered significant. *: p < 0.05; **: p < 0.01; ***: p < 0.001; @: p = 0.052 (PD1 on CD4⁺ T-cells in LTBI), p = 0.055 (PD1 on CD8⁺ T-cells in TB treated patients s). A. Cytokine production (median in pg/ml) in supernatants on day 5 following BCG stimulation (medium subtracted) for total PBMC (black) and B-cell depleted PBMC (grey). Data are expressed as mean + standard error of the mean. B. Expression of regulatory T-cell markers, or exhaustion markers PD1 and KLRG1 (as percentage of CD4⁺ or CD8⁺ T-cells) in total PBMCs (filled dots) or following CD19 depletion (open dots).