Fc alpha/mu receptor mediates endocytosis of IgM-coated microbes

Nat Immunol. 2000 Nov;1(5):441-6. doi: 10.1038/80886.


IgM is the first antibody to be produced in a humoral immune response and plays an important role in the primary stages of immunity. Here we describe a mouse Fc receptor, designated Fc alpha/microR, and its human homolog, that bind both IgM and IgA with intermediate or high affinity. Fc alpha/microR is constitutively expressed on the majority of B lymphocytes and macrophages. Cross-linking Fc alpha/microR expressed on a pro-B cell line Ba/F3 transfectant with soluble IgM or IgM-coated microparticles induced internalization of the receptor. Fc alpha/microR also mediated primary B lymphocyte endocytosis of IgM-coated Staphylococcus aureus. Thus, Fc alpha/microR is involved in the primary stages of the immune response to microbes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / metabolism*
  • B-Lymphocytes / immunology
  • Base Sequence
  • COS Cells
  • Cattle
  • Cell Line
  • Cloning, Molecular
  • DNA Primers / genetics
  • Endocytosis
  • Humans
  • Immunoglobulin A / metabolism
  • Immunoglobulin M / metabolism*
  • In Vitro Techniques
  • Macrophages / immunology
  • Mice
  • Molecular Sequence Data
  • Rats
  • Receptors, Fc / genetics
  • Receptors, Fc / metabolism*
  • Sequence Homology, Amino Acid
  • Staphylococcus aureus / immunology
  • Transfection


  • Antigens, CD
  • DNA Primers
  • Fc(alpha) receptor
  • Immunoglobulin A
  • Immunoglobulin M
  • Receptors, Fc
  • immunoglobulin M receptor