Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA.
Molecular and Cellular Biology Program, University of Washington, Seattle, WA.
J Immunol. 2024 Mar 15;212(6):1022-1028. doi: 10.4049/jimmunol.2300132.
Plasma cells secrete an abundance of Abs and are a crucial component of our immune system. The intestinal lamina propria harbors the largest population of plasma cells, most of which produce IgA. These Abs can bind to beneficial gut bacteria to reinforce intestinal homeostasis and provide protection against enteric pathogens. Plasma cells downregulate many cell-surface proteins commonly used to identify B cells. In mice, expression of the surface marker CD138 has been widely used to identify plasma cells in lymph nodes, bone marrow, and spleen. Intestinal plasma cells require liberation via extensive tissue processing involving treatment with collagenase. We report that detection of CD138 surface expression is reduced following collagenase treatment. Using a mouse in which yellow fluorescent protein expression is controlled by the plasma cell requisite transcription factor Blimp-1, we show that surface detection of transmembrane activator and CAML interactor captures a significant proportion of Ab-secreting plasma cells in the intestinal lamina propria and gut-draining mesenteric lymph nodes. Additionally, we describe a flow cytometry panel based on the detection of surface markers to identify murine B cell subsets in the intestinal lamina propria and, as a proof of concept, combine it with a cutting-edge fate-tracking system to characterize the fate of germinal center B cells activated in early life. By identifying plasma cells and other key intestinal B subsets in a manner compatible with several downstream applications, including sorting and culturing and in vitro manipulations, this efficient and powerful approach can enhance studies of mucosal immunity.
浆细胞分泌大量的 Abs，是我们免疫系统的重要组成部分。肠固有层拥有最多的浆细胞群体，其中大多数产生 IgA。这些 Abs 可以与有益的肠道细菌结合，以加强肠道稳态并提供针对肠道病原体的保护。浆细胞下调许多常用于识别 B 细胞的细胞表面蛋白。在小鼠中，表面标记物 CD138 的表达已被广泛用于识别淋巴结、骨髓和脾脏中的浆细胞。肠浆细胞需要通过涉及胶原酶处理的广泛组织处理来释放。我们报告说，胶原酶处理后 CD138 表面表达的检测减少了。使用由浆细胞必需转录因子 Blimp-1 控制黄色荧光蛋白表达的小鼠，我们表明跨膜激活剂和 CAML 相互作用物（transmembrane activator and CAML interactor）的表面检测捕获了固有层肠道和肠道引流肠系膜淋巴结中很大一部分分泌 Ab 的浆细胞。此外，我们描述了一个基于表面标记物检测的流式细胞术面板，用于鉴定固有层肠道中的小鼠 B 细胞亚群，并作为概念验证，将其与前沿的命运追踪系统结合，以表征早期生活中激活的生发中心 B 细胞的命运。通过以兼容几种下游应用的方式鉴定浆细胞和其他关键肠 B 细胞亚群，包括分选和培养以及体外操作，这种高效且强大的方法可以增强黏膜免疫研究。
