Regression analysis confirmed an age-independent association between HCMV infection and the proportions of the NKG2C+ subset (p < 0.001), as well as between the NKG2C LY2157299 mouse genotype and absolute numbers of NKG2C+ cells (p = 0.003) (Supporting Information Table 2). Stratification for both HCMV infection and NKG2C genotype further supported a relationship of the latter with the absolute numbers of NKG2C+ cells (Fig. 3A). The possibility that these results might be explained by age differences

or a skewed distribution of cases with congenital symptomatic and asymptomatic infection, displaying different levels of NKG2C+ cells (Fig. 1), was ruled out by multivariate analyses. Unexpectedly, NKG2C+/+ children were observed to display as well higher proportions (median 7.2% versus 4.6%; p = 0.003) and absolute numbers (median 359 versus 215 cells/mm3; p = 0.008) of total NK cells than NKG2C+/− children. Trametinib This finding was not

simply explained by the expansion of the NKG2C+ subset, as the numbers of NKG2A+, CD161+, and total NK cells appeared also higher in HCMV-positive NKG2C+/+ children compared to NKG2C+/− individuals (Fig. 3B–D). Multivariate regression analysis confirmed the relation of the NKG2C genotype with both the proportions (p = 0.001) and total numbers (p = 0.014) of NK cells, independently of age as a putative confounding variable [45, 46] (Supporting Information Table 2). In the present study, increased Tacrolimus (FK506) proportions of NKG2C+ NK cells were detected in children with past congenital HCMV infection; this immunophenotypic feature was particularly marked in symptomatic cases, as further illustrated by studies in twins. The detection in older patients of high proportions of circulating NKG2C+ cells years after symptomatic congenital HCMV infection (Table 2 and Supporting Information Table 1) highlighted the persistence of the NK-cell subset redistribution, consistent with observations in healthy adults (Muntasell and López-Botet, unpublished data). Though the proportions of NKG2C+ NK cells

appeared unrelated to age, the cross-sectional design of this study did not discriminate whether the increase of NKG2C+ cells resulted from a progressive cumulative process, as reported in cord blood transplantation recipients [31, 33]. Prospective longitudinal studies of the NK-cell immunophenotype in congenital and early postnatal HCMV infection are warranted to approach the dynamics of these events. We previously reported that CD94/NKG2C+ cells expanded in vitro in response to HCMV-infected fibroblasts, an effect that was prevented by early treatment with a blocking anti-CD94 mAb [41]. Based on these studies, we hypothesized that a cognate interaction of the activating KLR with HCMV-infected cells might drive a preferential proliferation, differentiation, and/or survival of the NKG2C+ NK-cell subset in response to cytokines (i.e., IL-15).