IMMUNOBIOLOGY Brief report Blood plasmacytoid dendritic cell responses to CpG oligodeoxynucleotides are impaired in human newborns

Plasmacytoid dendritic cells (pDCs) re-spond to unmethylated cytosine-phosphate-guanosine (CpG) motifs present in bacterial DNA or unmethylated synthetic oligodeoxynucleotides (CpG). In order to assess the function of pDCs in human newborns, interferon- (IFN-) production induced by CpG 2216 and phenotypic maturation of pDCs in re-sponse to CpG 2006 were compared in cord blood and adult blood. We first ob-served that neonatal pDCs displayed de-creased up-regulation of CD80, CD83, CD86, and CD40, whereas HLA-DR and CD54 up-regulation did not differ signifi-cantly between adults and neonates. We then found that the production of IFN- in response to CpG was dramatically im-paired in cord blood. This neonatal defect was detected both at protein and mRNA levels and was still present in blood of 4-day-old babies. Further experiments on enriched pDCs confirmed that these cells are intrinsically deficient in CpG-induced IFN- production at birth. These findings might be relevant to the increased suscep-tibility of human newborns to infections as well as to the use of CpG oligode-oxynucleotides as vaccine adjuvants in the neonatal period. (Blood. 2004;103