Characterization of Siglec-H as a novel endocytic receptor expressed on murine plasmacytoid dendritic cell precursors

Blood. 2006 May 1;107(9):3600-8. doi: 10.1182/blood-2005-09-3842. Epub 2006 Jan 5.

Abstract

We describe the cloning and characterization of Siglec-H, a novel murine CD33-related siglec-like molecule with 2 immunoglobulin domains. Unlike other CD33-related siglecs, Siglec-H lacks tyrosine-based signaling motifs in its cytoplasmic tail. Although Siglec-H has the typical structural features required for sialic acid binding, no evidence for carbohydrate recognition was obtained. Specific monoclonal and polyclonal antibodies (Abs) were raised to Siglec-H and used to define its cellular expression pattern and functional properties. By flow cytometry, Siglec-H was expressed specifically on plasmacytoid dendritic cell (pDC) precursors in bone marrow, spleen, blood, and lymph nodes. Staining of tissue sections showed that Siglec-H was also expressed in a subset of marginal zone macrophages in the spleen and in medullary macrophages in lymph nodes. Using bone marrow-derived pDC precursors that express Siglec-H, addition of Abs did not influence cytokine production, either in the presence or absence of synthetic oligodeoxynucleotides containing unmethylated cytosine-guanine motifs (CpG). In comparison, Siglec-H functioned as an endocytic receptor and mediated efficient internalization of anti-Siglec-H Abs. By immunizing mice with ovalbumin-conjugated anti-Siglec-H Ab in the presence of CpG, we demonstrate generation of antigen-specific CD8 T cells in vivo. Targeting Siglec-H may therefore be a useful way of delivering antigens to pDC precursors for cross-presentation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / metabolism
  • Antigens, Differentiation, Myelomonocytic / metabolism
  • Base Sequence
  • CD8-Positive T-Lymphocytes / immunology
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • Dendritic Cells / cytology
  • Dendritic Cells / immunology*
  • Dendritic Cells / metabolism*
  • Endocytosis / immunology*
  • Gene Expression
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / immunology*
  • Hematopoietic Stem Cells / metabolism*
  • Mice
  • Mice, Inbred Strains
  • Mice, Knockout
  • Molecular Sequence Data
  • N-Acetylneuraminic Acid / metabolism
  • Plasma Cells / cytology
  • Plasma Cells / immunology*
  • Plasma Cells / metabolism*
  • Receptors, Immunologic / genetics*
  • Receptors, Immunologic / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Sialic Acid Binding Ig-like Lectin 3

Substances

  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • Cd33 protein, mouse
  • DNA, Complementary
  • Receptors, Immunologic
  • Recombinant Fusion Proteins
  • Sialic Acid Binding Ig-like Lectin 3
  • N-Acetylneuraminic Acid