Experimental layout and expansion of PBMC in cultures supplemented with TG. Panel A: PBMC from consented healthy donors were initially exposed to IFN-γ (day 0), followed by different concentrations of either TG or αCD3 mAb (day +1) and IL-2 every 3 days. Further details are provided in Materials and Methods. Panel B: The frequency of CD3+CD8+ T cells, NK cells (CD3-CD16+CD56+) and CD3+CD56+ T cells from a representative PBMC sample at baseline is shown. Quadrant markers were set according to the proper isotypic control (not shown). The percentage of cells staining positively for a given antigen is indicated. Panel C: Cells were harvested weekly and counted. The number of cells was significantly higher after challenging with TG either at 250 (intTG; *p < 0.05) or 500 ng/ml (hiTG; **p < 0.05) compared with equal concentrations of αCD3 mAb (bottom row).