Analysis of the CD33-related siglec family reveals that Siglec-9 is an endocytic receptor expressed on subsets of acute myeloid leukemia cells and absent from normal hematopoietic progenitors

Leuk Res. 2007 Feb;31(2):211-20. doi: 10.1016/j.leukres.2006.05.026. Epub 2006 Jul 10.


CD33 (Siglec-3) is expressed on most acute myeloid leukemia (AML) cells and is currently being exploited as a therapeutic target. The purpose of this study was to investigate the expression pattern and potential utility of the seven recently described CD33-related siglecs as markers in AML. Besides CD33, Siglec-9 was the most highly expressed, particularly on AML cells with features of monocytic differentiation that also expressed Siglecs-5 and -7. Siglec-9 was absent from normal bone marrow myeloid progenitors but present on monocytic precursors. Using primary AML cells or transfected rat basophilic leukemia cells, Siglec-9 mediated rapid endocytosis of anti-Siglec-9 mAb. In contrast to CD33 and Siglec-5, levels of soluble Siglec-9 were low or undetectable in bone marrow plasma from AML patients and serum from normal donors. These features suggest that Siglec-9 provides not only a useful marker for certain subsets of AML, but also a potential therapeutic target.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Antigens, CD / analysis*
  • Antigens, CD / biosynthesis
  • Antigens, Differentiation, Myelomonocytic / analysis*
  • Antigens, Differentiation, Myelomonocytic / biosynthesis
  • Biomarkers, Tumor / analysis
  • Biomarkers, Tumor / biosynthesis
  • Flow Cytometry / methods
  • Hematopoietic Stem Cells / immunology*
  • Humans
  • Lectins / analysis*
  • Lectins / biosynthesis
  • Leukemia, Myeloid / immunology*
  • Sialic Acid Binding Ig-like Lectin 3
  • Sialic Acid Binding Immunoglobulin-like Lectins


  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • Biomarkers, Tumor
  • CD33 protein, human
  • Lectins
  • SIGLEC5 protein, human
  • SIGLEC7 protein, human
  • SIGLEC9 protein, human
  • Sialic Acid Binding Ig-like Lectin 3
  • Sialic Acid Binding Immunoglobulin-like Lectins