Marginal zone B-cell

Marginal zone B cells are noncirculating mature B cells that segregate anatomically into the marginal zone (MZ) of the spleen.[1] This region contains multiple subtypes of macrophages, dendritic cells, and the MZ B cells; it is not fully formed until 2 to 3 weeks after birth in rodents and 1 to 2 years in humans.[2] The MZ B cells within this region typically express high levels of IgM, CD21, CD1, CD9 with low to negligible levels of secreted-IgD, CD23, CD5, and CD11b that help to distinguish them phenotypically from follicular (FO) B cells and B1 B cells. In humans the splenic marginal zone B cells have evidence of somatic hypermutation in their immunoglobulin genes, indicating that they have been generated through a germinal centre reaction to become memory cells. [3]

Similar to B1 B cells, MZ B cells can be rapidly recruited into the early adaptive immune responses in a T cell independent manner.[4] The MZ B cells are especially well positioned as a first line of defense against systemic blood-borne antigens that enter the circulation and become trapped in the spleen.[5] It is believed they are especially reactive to bacterial cell wall components and self-antigens which are the products of aging.[4] MZ B cells also display a lower activation threshold than their FO B cell counterparts with heightened propensity for plasma cell differentiation that contributes further to the accelerated primary antibody response.[6]

In specimens where the tyrosine kinase for Pyk-2 has been knocked-out, marginal zone B-cells will fail to develop while B-1 cells will still be present.[4]

MZ B-cells are the only B-cells dependent on NOTCH2 signaling for proliferation.[4]

References

  1. ↑ Martin F, Kearney JF. Marginal-zone B cells. Nat Rev Immunol. 2002;2(5):323–335.
  2. ↑ MacLennan IC, Bazin H, Chassoux D, et al. Comparative analysis of the development of B cells in marginal zones and follicles. Adv Exp Med Biol. 1985;186:139–144.
  3. ↑ Dunn-Walters, DK; Isaacson, PG; Spencer, J (1995). "Analysis of mutations in immunoglobulin heavy chain variable region genes of microdissected marginal zone (MGZ) B cells suggests that the MGZ of human spleen is a reservoir of memory B cells". J. Exp. Med. 182: 559–566. doi:10.1084/jem.182.2.559. PMC 2192131.
  4. 1 2 3 4 Hardy, Richard (2008). "Chapter 7: B Lymphocyte Development and Biology". In Paul, William. Fundamental Immunology (Book) (6th ed.). Philadelphia: Lippincott Williams & Wilkins. pp. 237–269. ISBN 0-7817-6519-6.
  5. ↑ Balazs M, Martin F, Zhou T, et al. "Blood dendritic cells interact with splenic marginal zone B cells to initiate T-independent immune responses". Immunity. 2002;17(3):341–352.
  6. ↑ Lopes-Carvalho T, Foote J, Kearney JF. Marginal zone B cells in lymphocyte activation and regulation. Curr Opin Immunol. 2005; 17(3):244–250
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