Interaction of the capsular polysaccharide A from Bacteroides fragilis with DC-SIGN on human dendritic cells is necessary for its processing and presentation to T cells.

• Main Authors: Karien eBloem, Juan J Garcia-Vallejo, Ilona M Vuist, Brian eCobb, Sandra J van Vliet, Yvette eVan Kooyk
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2013-05-01
• Series: Frontiers in Immunology
• Subjects: dendritic cell; T cell proliferation; pathogen; C-type lectin; polysaccharide
• Online Access: http://journal.frontiersin.org/Journal/10.3389/fimmu.2013.00103/full

The zwitterionic capsular polysaccharide A (PSA) of Bacteroides fragilis is the first carbohydrate antigen described to be presented in major histocompatibility complex (MHC) class II for the induction of CD4+ T cell responses. However, the identity of the receptor mediating binding and internalization of PSA in antigen presenting cells remains elusive. C-type lectins are glycan-binding receptors known for their capacity to target ligands for antigen presentation to T cells. Here, we investigated whether C-type lectins were involved in the internalization of PSA and identified dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) as the main receptor for PSA on human dendritic cells. The induction of PSA-specific T cell proliferation appeared to be completely dependent on DC-SIGN. These data reveal a crucial role for DC-SIGN in the endocytosis and routing of PSA in human dendritic cells for the efficient stimulation of PSA-specific CD4+ T cells.