Deficient IL-12(p35) Gene Expression by Dendritic Cells Derived from Neonatal Monocytes

Abstract

To gain insight into the defects responsible for impaired Th1 responses in human newborns, we analyzed the production of cytokines by dendritic cells (DC) derived from cord blood monocytes. We observed that neonatal DC generated from adherent cord blood mononuclear cells cultured for 6 days in the presence of IL-4 and GM-CSF show a phenotype similar to adult DC generated from adherent PBMC, although they express lower levels of HLA-DR, CD80, and CD40. Measurement of cytokine levels produced by neonatal DC upon stimulation by LPS, CD40 ligation, or poly(I:C) indicated a selective defect in the synthesis of IL-12. Determination of IL-12(p40) and IL-12(p35) mRNA levels by real-time RT-PCR revealed that IL-12(p35) gene expression is highly repressed in stimulated neonatal DC whereas their IL-12(p40) gene expression is not altered. The addition of rIFN-γ to LPS-stimulated newborn DC restored their expression of IL-12(p35) and their synthesis of IL-12 (p70) up to adult levels. Moreover, we observed that neonatal DC are less efficient than adult DC to induce IFN-γ production by allogenic adult CD4+ T cells. This defect was corrected by the addition of rIL-12. We conclude that neonatal DC are characterized by a severe defect in IL-12(p35) gene expression which is responsible for an impaired ability to elicit IFN-γ production by T cells.

Early life T cell responses to pneumococcal conjugates increase with age and determine the polysaccharide‐specific antibody response and protective efficacy

“…Several groups have demonstrated that DC from both human cord-blood [50], and neonatal mice [51] show decreased capacity of antigen presentation and stimulation of CD4 + T cells. An impaired function of human neonatal DC is dependent on their reduced ability to produce IL-12 [52], which is one explanation for the Th2 bias of neonatal T cell responses, as IL-12 plays a crucial role in promoting Th1 development by inducing IFN-c production by Th1 cells and NK cells [53]. Despite the limitations of the immune system in early life, successful pediatric vaccines exist.…”

Inhibition of phosphoinositide 3-kinase enhances TRIF-dependent NF-κB activation and IFN-β synthesis downstream of Toll-like receptor 3 and 4

“…Generation of monocyte-derived DC DC were generated from peripheral blood mononuclear cells (PBMC) obtained from healthy donors as previously described [43]. After 6 days, nonadherent cells corresponding to DCenriched fraction routinely contained more than 95% of DC as assessed by morphological and FACS analysis as described earlier [43].…”

“…After 6 days, nonadherent cells corresponding to DCenriched fraction routinely contained more than 95% of DC as assessed by morphological and FACS analysis as described earlier [43].…”

“…Reverse transcription and realtime PCR were carried out using Light-Cycler-RNA Master Hybridization probes (one-step procedure) on a Lightcycler J apparatus (Roche Diagnostics). The real-time PCR conditions were previously described [43]. The oligonucleotides sequences used for amplification of the IFN-b mRNA were respectively: sense primer, 5 0 -GGATGCAGGAAGGAGAT-CACTG-3 0 ; anti-sense primer, 5 0 -CGATCCACACGGAG-TACTTG-3 0 ; probe, (6-Fam) CCCTGGCACCAGCACAATG (Tamra) (phosphate)-3 0 .…”

Genetic regulation of immune responses to vaccines in early life

“…Early immunization is required to impact on this mortality, but the development of vaccines that are effective at birth is impeded by the immaturity of the immune system. [3][4][5] The antibody (Ab) responses to T-cell-independent and many T-celldependent vaccine antigens are lower in young infants when compared to older children or adults. [6][7][8][9][10] Qualitative differences in Ab responses in infants include reduced Ab avidity and repertoire, and different immunoglobulin G (IgG) subclass distribution.…”