The C-type lectin receptor CLEC9A mediates antigen uptake and (cross-)presentation by human blood BDCA3+ myeloid dendritic cells

Blood. 2012 Mar 8;119(10):2284-92. doi: 10.1182/blood-2011-08-373944. Epub 2012 Jan 10.

Abstract

CLEC9A is a recently discovered C-type lectin receptor involved in sensing necrotic cells. In humans, this receptor is selectively expressed by BDCA3(+) myeloid dendritic cells (mDCs), which have been proposed to be the main human cross-presenting mDCs and may represent the human homologue of murine CD8(+) DCs. In mice, it was demonstrated that antigens delivered with antibodies to CLEC9A are presented by CD8(+) DCs to both CD4(+) and CD8(+) T cells and induce antitumor immunity in a melanoma model. Here we assessed the ability of CLEC9A to mediate antigen presentation by human BDCA3(+) mDCs, which represent < 0.05% of peripheral blood leukocytes. We demonstrate that CLEC9A is only expressed on immature BDCA3(+) mDCs and that cell surface expression is lost after TLR-mediated maturation. CLEC9A triggering via antibody binding rapidly induces receptor internalization but does not affect TLR-induced cytokine production or expression of costimulatory molecules. More importantly, antigens delivered via CLEC9A antibodies to BDCA3(+) mDCs are presented by both MHC class I (cross-presentation) and MHC class II to antigen-specific T cells. We conclude that CLEC9A is a promising target for in vivo antigen delivery in humans to increase the efficiency of vaccines against infectious or malignant diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigen Presentation / immunology*
  • Antigens, CD / immunology
  • Antigens, CD / metabolism
  • Antigens, Surface / immunology
  • Antigens, Surface / metabolism
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism
  • Cells, Cultured
  • Cross-Priming / immunology*
  • Dendritic Cells / immunology*
  • Dendritic Cells / metabolism
  • Endocytosis / immunology
  • Flow Cytometry
  • Histocompatibility Antigens Class II / immunology
  • Histocompatibility Antigens Class II / metabolism
  • Humans
  • Lectins, C-Type / immunology*
  • Lectins, C-Type / metabolism
  • Minor Histocompatibility Antigens
  • Myeloid Cells / immunology
  • Myeloid Cells / metabolism
  • Receptors, Cell Surface / immunology
  • Receptors, Cell Surface / metabolism
  • Receptors, Mitogen / immunology*
  • Receptors, Mitogen / metabolism
  • Thrombomodulin
  • Toll-Like Receptors / immunology
  • Toll-Like Receptors / metabolism

Substances

  • Antigens, CD
  • Antigens, Surface
  • CLEC9a protein, human
  • DEC-205 receptor
  • Histocompatibility Antigens Class II
  • Lectins, C-Type
  • Minor Histocompatibility Antigens
  • Receptors, Cell Surface
  • Receptors, Mitogen
  • THBD protein, human
  • Thrombomodulin
  • Toll-Like Receptors