Natural killer (NK) cells are vital in the antiviral response regulated by inhibitory and activating receptors, including NKG2 and KIR families, which bind HLA-I. While the adaptive features of NK cells in response to human cytomegalovirus (hCMV) have been well described, their behavior during Epstein-Barr virus (EBV) infection and the influence of KIR-HLA combinations in healthy carriers of these viruses remains unclear. We performed high-resolution HLA genotyping, phenotypic profiling of NK cell subsets, and serological testing for hCMV and EBV-specific IgG in 85 healthy adult donors. hCMV-seropositive individuals exhibited significant expansions of NKG2C+ and HLA-DR+ NK cell subsets, with the proportion of NKG2C+ cells strongly correlating with hCMV-IgG titers. In contrast, EBV infection was associated with increased frequencies of terminally differentiated CD56dim, NKG2A-, CD57+ NK cells and elevated expression of inhibitory KIRs, but not NKG2C or HLA-DR. EBV-IgG titers correlated with CD57 and KIR2DS4 levels. Among KIR2DS4-expressing donors, carriage of at least one HLA-C2 allele was associated with elevated EBV-IgGs. The precise analysis of KIR2DL2/DL3, KIR2DS4, and KIR2DL1 revealed dependencies on EBV-IgG titers, with no associations with hCMV. These findings highlight the differential impacts of hCMV and EBV on NK cells and underscore the relevance of HLA-KIR landscapes in shaping antiviral immunity.
Keywords: EBV; HLA; KIR; NK cells; NKG2; antiviral immunity; hCMV.
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