Figure 1.
(a) ELISPOT interferon-γ (IFN-γ) responses against cytomegalovirus (CMV) -encoded peptides by donor Y26. Responses are expressed as spot-forming cells (SFC) per 100 000 peripheral blood mononuclear cells (PBMC) after subtracting the background responses against dumethyl sulphoxide (< 20 SFC/105 PBMC). HLA-B7-restricted TPR peptide was used as a further control. These responses were also visualized by flow cytometry (b) after staining for cytoplasmic IFN-γ induced by a 6-hr incubation with each peptide. The PBMC from donor Y04 were also incubated with major histocompatibility complex–peptide tetramers (c), representing CMV immediate early 1 protein (IE-1) epitopes (YVL, QIK, ELK), CMV early pp50 (VTE) and late pp65 epitopes (YSE and NLV) and an Epstein–Barr virus epitope (GLC). Cells were counter-stained with anti-CD8. Frequencies (%) of CD8 T cells binding the given tetramer are indicated in the upper right quadrant.