In vitro T-cell expansion. Two batches of PBMCs from each donor were peptide-stimulated (10 µmol/L) over a course of 9 days. The first batch was analyzed on day 16 without further restimulation. The second batch was restimulated with CD3/CD28-coated beads on day 14 and analyzed on day 21. Cells were analyzed using dextramer staining on day 0 (ex vivo), day 16 (first batch), and day 21 (second batch). After gating cells with the forward and side light scatter properties of lymphocytes, dextramer-positive cells were measured as percentage of CD3/CD8-positive cells. Empty dextramer was used as negative control; CMV-pp65 was used as positive control. (A) Fluorescence-activated cell sorter (FACS) dot plots of representative female subject UPN T6. (B) FACS dot plots of representative male subject UPN T14.