美国匹兹堡大学Mark Jay Shlomchik研究团队近日发现，肝脏是B细胞响应埃立克体（Ehrlichia muris）的产生位点。2019年11月12日，国际知名学术期刊《免疫》发表了这一成果。

据研究人员介绍，B细胞对埃立克体的反应主要由浆母细胞（PB）决定，很少有（如果有的话）生殖器中心（GC），但它会产生保护性免疫球蛋白M（IgM）记忆B细胞（MBC），其表达转录因子T-bet并带有V区突变。

由于埃立克体主要感染肝脏，因此他们研究了肝脏B细胞反应和脾脏的本质。受感染的肝脏中的B细胞增殖并经历体细胞高频突变（SHM）。Vh区测序揭示了脾脏和肝脏之间的克隆运输，并经常随后出现T-bet阳性MBC的局部克隆扩增和实质内定位。T-bet阳性MBC表达了MBC亚群标志物CD80和PD-L2。许多T-bet阳性MBC缺乏CD11b或CD11c表达，但具有边缘区（MZ）B细胞表型并在脾脏MZ上定殖，这显示T-bet阳性MBC可塑性。因此，肝脏和脾脏是B细胞反应的产生位点，它们包括V区突变并导致肝脏MBC定位。

附：英文原文

Title: Liver Is a Generative Site for the B Cell Response to Ehrlichia muris

Author: Nikita Trivedi, Florian Weisel, Shuchi Smita, Stephen Joachim, Muhamuda Kader, Aditya Radhakrishnan, Chris Clouser, Aaron M. Rosenfeld, Maria Chikina, Francois Vigneault, Uri Hershberg, Nahed Ismail, Mark Jay Shlomchik

Issue&Volume: November 12, 2019

Abstract: The B cell response to Ehrlichia muris is dominated by plasmablasts (PBs), with few—if any—germinal centers (GCs), yet itgenerates protective immunoglobulin M (IgM) memory B cells (MBCs) that express thetranscription factor T-bet and harbor V-region mutations. Because Ehrlichia prominently infects the liver, we investigated the nature of liver B cell responseand that of the spleen. B cells within infected livers proliferated and underwentsomatic hypermutation (SHM). Vh-region sequencing revealed trafficking of clones betweenthe spleen and liver and often subsequent local clonal expansion and intraparenchymallocalization of T-bet+ MBCs. T-bet+ MBCs expressed MBC subset markers CD80 and PD-L2. Many T-bet+ MBCs lacked CD11b or CD11c expression but had marginal zone (MZ) B cell phenotypesand colonized the splenic MZ, revealing T-bet+ MBC plasticity. Hence, liver and spleen are generative sites of B cell responses,and they include V-region mutation and result in liver MBC localization.

DOI: 10.1016/j.immuni.2019.10.004

Source: https://www.cell.com/immunity/fulltext/S1074-7613(19)30448-0