Lewis X oligosaccharides targeting to DC-SIGN enhanced antigen-specific immune response

Dendritic cell-specific intercellular-adhesion-molecule-grabbing non-integrin (DC-SIGN) is a potential target receptor for vaccination purposes. In the present study, we employed Lewis X (Le(x)) oligosaccharides, which mimic natural ligands, to target ovalbumin (OVA) to human dendritic cells (DCs) via DC-SIGN, to investigate the effect of this DC-SIGN-targeting strategy on the OVA-specific immune response. We demonstrated that Le(x) oligosaccharides could enhance the OVA-specific immune response as determined by enzyme-linked immunospot assay (ELISPOT), intracellular interferon-gamma staining and Cr-51-release assay. An almost 300-fold lower dose of Le(x)-OVA induced balanced interferon-gamma-secreting cells compared to OVA alone. Furthermore, secretion of interleukin-10, a reported mediator of immune suppression related to DC-SIGN, was not increased by Le(x)-OVA, either alone or together with sCD40L-stimulated groups. A blocking antibody against DC-SIGN (12507) reduced the numbers of interferon-gamma-secreting cells during Le(x)-OVA stimulation, yet it did not prevent Le(x) oligosaccharides from promoting the secretion of interleukin-10 that was induced by ultra-pure lipopolysaccharide. These results suggested that the strategy of DC-SIGN targeting mediated by Le(x) oligosaccharides could promote a T-cell response. This DC-targeting may imply a novel vaccination strategy.