Preferential expansion of CD94/NKG2C⁺ NK cells upon stimulation with HCMV-infected autologous or allogeneic fibroblasts. (A) PBLs from HCMV⁺ and HCMV^- donors were cocultured with mock- and AD169-infected (MOI = 1) MRC-5 cells. Two-color analysis was carried out at day 10 with an anti-CD3 mAb combined to anti-NKG2C or -NKG2A mAbs. The results are representative of the patterns of response observed in 6 of 11 HCMV⁺ individuals, and in 4 HCMV^- donors. (B) PBLs from an HCMV⁺ donor were cocultured with mock- and AD169-infected allogeneic (MRC-5) or autologous fibroblasts, and samples were analyzed at day 10, as described in panel A. Similar results were obtained in 6 different experiments with PBLs from 2 different individuals.