Figure 4

Cytotoxic effects of IE-1 _1–15 and IE-1 _5–19 peptide-specific CTLs against CMV-infected fibroblast. PBMCs from three HLA-A*2402 HCMV-seropositive donors (Donors 9,10 and11) were sensitized in vitro for two weeks with IE-1_1–15MESSAKRKMDPDNPD and IE-1_5–19 AKRKMDPDNPDEGPS and the in vitro sensitized cells were tested for cytotoxicity against HLA-matched HCMV-infected fibroblast. The cytotoxicity assay was carried out by measuring ⁵¹Cr release from HLA-A*2402 HCMV-infected fibroblasts. PBMCs from Donor 9 (Figure 4A) and Donor 10 (Figure 4B) that were in vitro sensitized for 2 weeks with IE-1_1–15 MESSAKRKMDPDNPD were highly cytotoxic to HLA-A*2402 HCMV-infected fibroblasts causing as much targeted cell lysis as PBMCs sensitized with a positive control. However, in Donor 11, IE-1_5–19AKRKMDPDNPDEGPS showed higher cytotoxicity to HCMV-infected fibroblasts than that of IE-1_1–15MESSAKRKMDPDNPD (Figure 4C). PMBCs stimulated with the HLA-A24-restricted HCMV pp65 epitope HCMV A24 (pp65_341–350) was used as positive control and PBMCs stimulated with the HCMV-A33 restricted epitope CMV A33 (pp65_91–100) peptide and PBMCs simulated only with IL-2 (IL-2) were used as negative controls.