Feldhahn Niklas, Schwering Ines, Lee Sanggyu, Wartenberg Maria, Klein Florian, Wang Hui, Zhou Guolin, Wang San Ming, Rowley Janet D, Hescheler Jürgen, Krönke Martin, Rajewsky Klaus, Küppers Ralf, Müschen Markus
Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, 50931 Köln, Germany.
J Exp Med. 2002 Nov 18;196(10):1291-305. doi: 10.1084/jem.20020881.
To identify changes in the regulation of B cell receptor (BCR) signals during the development of human B cells, we generated genome-wide gene expression profiles using the serial analysis of gene expression (SAGE) technique for CD34(+) hematopoietic stem cells (HSCs), pre-B cells, naive, germinal center (GC), and memory B cells. Comparing these SAGE profiles, genes encoding positive regulators of BCR signaling were expressed at consistently lower levels in naive B cells than in all other B cell subsets. Conversely, a large group of inhibitory signaling molecules, mostly belonging to the immunoglobulin superfamily (IgSF), were specifically or predominantly expressed in naive B cells. The quantitative differences observed by SAGE were corroborated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry. In a functional assay, we show that down-regulation of inhibitory IgSF receptors and increased responsiveness to BCR stimulation in memory as compared with naive B cells at least partly results from interleukin (IL)-4 receptor signaling. Conversely, activation or impairment of the inhibitory IgSF receptor LIRB1 affected BCR-dependent Ca(2+) mobilization only in naive but not memory B cells. Thus, LIRB1 and IL-4 may represent components of two nonoverlapping gene expression programs in naive and memory B cells, respectively: in naive B cells, a large group of inhibitory IgSF receptors can elevate the BCR signaling threshold to prevent these cells from premature activation and clonal expansion before GC-dependent affinity maturation. In memory B cells, facilitated responsiveness upon reencounter of the immunizing antigen may result from amplification of BCR signals at virtually all levels of signal transduction.
为了确定人类B细胞发育过程中B细胞受体(BCR)信号调节的变化,我们使用基因表达序列分析(SAGE)技术,对CD34(+)造血干细胞(HSC)、前B细胞、幼稚B细胞、生发中心(GC)B细胞和记忆B细胞进行全基因组基因表达谱分析。比较这些SAGE图谱,编码BCR信号正调节因子的基因在幼稚B细胞中的表达水平始终低于所有其他B细胞亚群。相反,一大类抑制性信号分子,大多属于免疫球蛋白超家族(IgSF),在幼稚B细胞中特异性表达或主要表达。SAGE观察到的定量差异通过半定量逆转录-聚合酶链反应(RT-PCR)和流式细胞术得到证实。在功能试验中,我们发现与幼稚B细胞相比,记忆B细胞中抑制性IgSF受体的下调和对BCR刺激反应性的增加至少部分是由白细胞介素(IL)-4受体信号传导引起的。相反,抑制性IgSF受体LIRB1的激活或损伤仅影响幼稚B细胞而非记忆B细胞中依赖BCR的Ca(2+)动员。因此,LIRB1和IL-4可能分别代表幼稚B细胞和记忆B细胞中两个不重叠的基因表达程序的组成部分:在幼稚B细胞中,一大类抑制性IgSF受体可以提高BCR信号阈值,以防止这些细胞在依赖GC的亲和力成熟之前过早激活和克隆扩增。在记忆B细胞中,再次遇到免疫抗原时反应性增强可能是由于在信号转导的几乎所有水平上BCR信号的放大。