Why do we need IgM memory B cells?

Federica Capolunghi, M. Manuela Rosado, Matilde Sinibaldi, Alaitz Aranburu, Rita Carsetti

Research output: Contribution to journalArticlepeer-review


Immunological memory is our reservoir of ready-to-use antibodies and memory B cells. Because of immunological memory a secondary infection will be very light or not occur at all. Antibodies and cells, generated in the germinal center in response to the first encounter with antigen, are highly specific, remain in the organism virtually forever and are mostly of IgG isotype. Long lived plasma cells homing to the bone marrow ensure the constant production of protective antibodies, whereas switched memory B cells proliferate and differentiate in response to secondary challenge. IgM memory B cells represent our first-line defense against infections. They are generated by a T-cell independent mechanism probably triggered by Toll-like receptor-9. They produce natural antibodies with anti-bacterial specificity and the spleen is indispensable for their maintenance.We will review the characteristics and functions of IgM memory B cells that explain their importance in the immediate protection from pathogens. IgM memory B cells, similar to mouse B-1a B cells, may be a remnant of a primitive immune system that developed in the spleen of cartilaginous fish and persisted throughout evolution notwithstanding the sophisticated tools of the adaptive immune system.

Original languageEnglish
Pages (from-to)114-120
Number of pages7
JournalImmunology Letters
Issue number2
Publication statusPublished - 2013


  • CpG
  • IgM memory B cells
  • Memory B cells
  • Natural antibodies
  • Spleen
  • TLR9

ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy
  • Medicine(all)

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