Antibodies play pivotal roles in host protection. Once generated, serum antibodies provide rapid and system-wide protection against virtually any type of microbe or toxin, and in the gut, antibodies combat infection while also regulating the composition of commensal microbes. The vast majority of antibodies are generated by terminally differentiated B cells known as plasma cells. It is thought that fully functional plasma cells routinely and consistently secrete some 10 000 antibodies/s. To achieve high-throughput antibody secretion, activated B cells undergo a stunning metamorphosis (Figure 1A): Overall increases in cellular volume are accompanied by a massive expansion of the endoplasmic reticulum and Golgi together with increased expression of numerous proteins that serve to promote protein translation and secretion. In essence, plasma cell differentiation might be viewed as the formation of protein secretion machines.

With this special issue, we have assembled a series of reviews focused on the unique biology of the plasma cell. Many of these articles center on the biochemistry and molecular biology surrounding the transition from an activated B cell to a fully functional plasma cell. These articles look at this process from several vantage points from gene regulation to organelle biogenesis. You could say that collectively these reviews center on the question of how to build a plasma cell from a B cell. Additionally, you will find several reviews on emerging data, suggesting that plasma cells including IgA-secreting plasma cells can take on functions in addition to antibody secretion. In addition, because IgA-secreting plasma cells in the gut outnumber all other plasma cells, we include an article on the continually enigmatic function(s) of IgA antibodies. Finally, because antibodies can at times cause disease, we conclude with reviews of current attempts to exploit the unique biology of plasma cells to curb the production of pathogenic antibodies.

抗体在宿主保护中起着关键作用。一旦产生，血清抗体就可以提供针对几乎任何类型的微生物或毒素的快速和全系统保护，并且在肠道中，抗体可以对抗感染，同时还可以调节共生微生物的组成。绝大多数抗体是由终末分化的 B 细胞（称为浆细胞）产生的。据认为，功能齐全的浆细胞通常会持续分泌约 10 000 个抗体/秒。为了实现高通量抗体分泌，活化的 B 细胞经历了惊人的变态（图 1A）：细胞体积的整体增加伴随着内质网和高尔基体的大规模扩张，以及许多促进蛋白质翻译的蛋白质表达增加和分泌物。在本质上，

在本期特刊中，我们汇集了一系列关于浆细胞独特生物学的评论。这些文章中有许多围绕着从活化的 B 细胞到功能齐全的浆细胞转变的生物化学和分子生物学展开。这些文章从基因调控到细胞器生物发生的几个有利角度审视了这一过程。你可以说这些评论集中在如何从 B 细胞构建浆细胞的问题上。此外，您会发现一些关于新兴数据的评论，表明包括 IgA 分泌浆细胞在内的浆细胞除了分泌抗体外还可以承担其他功能。此外，由于肠道中分泌 IgA 的浆细胞数量超过所有其他浆细胞，因此我们收录了一篇关于 IgA 抗体持续神秘功能的文章。