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‐β 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‐β and IFN‐λ1 were produced at lower levels by neonatal as compared with adult DC. In contrast, neonatal and adult DC produced similar levels of IFN‐α 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‐α production by neonatal DC exposed to HCMV are likely to influence the quality of the T lymphocyte response to HCMV infection in early life.