Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality. Previous studies have suggested that T cell responses may contribute to RSV immunopathology, which could be driven by dendritic cells (DCs). DCs are productively infected by RSV, and during RSV infections, there is an increase of DCs in the lungs with a decrease in the blood. Pediatric populations are particularly susceptible to severe RSV infections, however DC responses to RSV from pediatric populations have not been examined. In this study, primary isolated DCs from cord blood and adult peripheral blood were compared after RSV-infection. Transcriptional profiling and biological network analysis identified transforming growth factor (TGF)-b and associated signaling molecules as differentially regulated in the two age groups. TGF-b1 was decreased in RSV-infected adult blood DCs, but increased in RSV-infected cord blood DCs. Co-culture of adult RSV-infected DCs with autologous T-cells induced secretion of interferon gamma (IFNg), IL-12p70, IL-2, and tumor necrosis factor alpha (TNFa). Conversely, co-culture of cord RSV-infected DCs and autologous T-cells induced secretion of IL-4, IL-6, IL-1b, and IL-17. Addition of purified TGF-b1 to adult DC-T cell co-cultures reduced secretion of IFNg, IL-12p70, IL-2, and TNFa, which addition of a TGF-b chemical inhibitor to cord DC-T cell co-cultures increased secretion of IL-12p70. These data suggest that TGF-b acts as a major regulator of RSV DC-T cell responses, which could contribute to immunopathology during infancy.

Three sets of adult peripheral DCs were analyzed and three sets of cord blood DCs. The DCs from each donor were divided in half and either mock infected or infected with RSV and each (12 samples total) were used for affymetrix array analsis. The donor-matched mock infected DC hybridyzation was used as the reference sample for the RSV infected.