Immunological memory is a composite of lasting antibody titers maintained by plasma cells in conjunction with memory T and B cells. Memory B cells are a critical reservoir for plasma cell generation in the secondary response. Identification of memory B cells requires that they be distinguished from naïve, activated, and germinal center precursors and from plasma cells. Memory B cells are heterogeneous in isotype usage, immunoglobulin mutational content, and phenotypic marker expression. Phenotypic subsets of memory B cells are defined by PD-L2, CD80, and CD73 expression in mice, by CD27 and FCRL4 expression in humans and by T-bet in both mice and humans. These subsets display marked functional heterogeneity, including the ability to rapidly differentiate into plasma cells versus seed germinal centers in the secondary response. Memory B cells are located in the spleen, blood, other lymphoid organs, and barrier tissues, and recent evidence indicates that some memory B cells may be dedicated tissue-resident populations. Open questions about memory B cell longevity, renewal and progenitor-successor relationships with plasma cells are discussed.

中文翻译：

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记忆 B 细胞和浆细胞：体液免疫的分化连续体

免疫记忆是由浆细胞与记忆 T 细胞和 B 细胞共同维持的持久抗体滴度的复合物。记忆 B 细胞是二级反应中浆细胞生成的关键储存库。识别记忆 B 细胞需要将它们与幼稚、活化和生发中心前体以及浆细胞区分开来。记忆 B 细胞在同种型使用、免疫球蛋白突变内容和表型标记表达方面是异质的。记忆 B 细胞的表型亚群由小鼠中的 PD-L2、CD80 和 CD73 表达、人类中的 CD27 和 FCRL4 表达以及小鼠和人类中的 T-bet 定义。这些亚群显示出显着的功能异质性，包括在二级反应中快速分化为浆细胞与种子生发中心的能力。记忆 B 细胞位于脾脏、血液、其他淋巴器官和屏障组织中，最近的证据表明，一些记忆 B 细胞可能是专门的组织驻留群体。讨论了有关记忆 B 细胞寿命、更新和与浆细胞的祖-继细胞关系的开放性问题。