%0 Journal Article %A Hendricks, Jacobus %A Bos, Nicolaas A. %A Kroese, Frans G.M. %D 2018 %I Begell House %K memory B cells, marginal zone (MZ), immunoglobulin heavy (IGH) chain genes, spleen, rat %N 2 %P 145-158 %R 10.1615/CritRevImmunol.2018024985 %T Heterogeneity of Memory Marginal Zone B Cells %U https://www.dl.begellhouse.com/journals/2ff21abf44b19838,443ae0ff4b5271d1,1ad3fc0440adab85.html %V 38 %X The marginal zone (MZ) is largely composed of a unique subpopulation of B cells, the so-called MZ-B cells. At a molecular level, memory B cells are characterized by the presence of somatically mutated IGV genes. The earliest studies in the rat have documented the presence of hapten-specific MZ-B cells after immunization in the MZ. This work later received experimental support demonstrating that the IGHV-Cμ transcripts expressed by phenotypically defined splenic MZ-B cells (defined as CD90negIgMhighIgDlow B cells) can carry somatic hypermutation. However, only a minor fraction (< 10%–20%) of these MZ-B cells is mutated and is considered to represent memory B cells. Memory B cells can either be class-switched (IgG, IgA, IgE), or non–class-switched (IgM) B cells. B cells in the MZ are a heterogeneous population of cells and both naïve MZ-B cells; class switched and unswitched memory MZ-B cells are present at this unique site in the spleen. Naïve MZ-B cells carry unmutated Ig genes, produce low-affinity IgM molecules and constitute a first line of defense against invading pathogens. Memory MZ-B cells express high-affinity Ig molecules, directed to (microbial) antigens that have been encountered. In this review, we report on the memory compartment of splenic MZ-B cells in the rat to provide insights into the origin and function of these memory MZ-B cells. %8 2018-04-26