IL‐12 and type I IFN response of neonatal myeloid DC to human CMV infection

Following congenital human CMV (HCMV) infection, 15-20% of infected newborns develop severe health problems whereas infection in immunocompetent adults rarely causes illness. The immaturity of neonatal antigen presenting cells could play a pivotal role in this susceptibility. Neonatal myeloid DC were shown to be deficient in IFN-beta and IL-12 synthesis in response to TLR triggering. We studied the response of cord and adult blood-derived myeloid DC to HCMV infection. Neonatal and adult DC were equally susceptible to in vitro HCMV infection. Among immunomodulatory cytokines, IL-12, IFN-beta and IFN-lambda1 were produced at lower levels by neonatal as compared with adult DC. In contrast, neonatal and adult DC produced similar levels of IFN-alpha and IFN-inducible genes. Microarray analysis indicated that among the more than thousand genes up- or down-regulated by HCMV infection of myeloid DC, 88 were differently regulated between adult and neonatal DC. We conclude that neonatal and adult DC trigger a partly different response to HCMV infection. The deficient IL-12 and mature IFN-alpha production by neonatal DC exposed to HCMV are likely to influence the quality of the T lymphocyte response to HCMV infection in early life.