The molecular characterization of the fetal stem cell marker AA4

Immunity. 1999 Jun;10(6):691-700. doi: 10.1016/s1074-7613(00)80068-0.


We have identified and characterized the stem cell antigen AA4. This molecule is a type I transmembrane protein whose overall structure suggests a role in cell adhesion. During fetal ontogeny (days 9-14 of development), AA4 is expressed in three major cell types: vascular endothelial cells, aorta-associated hematopoietic clusters, and primitive fetal liver hematopoietic progenitors. In the adult, AA4 is abundant in lung, heart, and whole bone marrow. In the adult hematopoietic compartment, aa4 transcripts are present in bone marrow CD34(-/lo) Lin- Sca-1+ c-Kit+ and CD34hi Lin- Sca-1+ c-Kit+ stem and progenitor cell subsets. Our observations suggest that AA4 plays a role in cell-cell interactions during hematopoietic and vascular development.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Amino Acid Sequence
  • Animals
  • Antigens, Surface / biosynthesis
  • Antigens, Surface / chemistry*
  • Base Sequence
  • Biomarkers / chemistry
  • Cloning, Molecular
  • Fetus / immunology*
  • Hematopoietic Stem Cells / chemistry
  • Hematopoietic Stem Cells / immunology*
  • Hematopoietic Stem Cells / metabolism
  • Humans
  • In Situ Hybridization
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • RNA, Messenger / analysis
  • Recombinant Proteins / biosynthesis
  • Sequence Alignment
  • Sequence Analysis, DNA


  • Antigens, Surface
  • Biomarkers
  • RNA, Messenger
  • Recombinant Proteins

Associated data

  • GENBANK/AF081789