RNA-seq profiles of germinal center B cells from spleens of wild-type and Il21r-deficient mice after immunization with NP-KLH

Humoral immune responses require germinal centres (GC) for antibody affinity maturation. Within GC, B-cell proliferation and mutation are segregated from affinity-based positive selection in the dark zone (DZ) and light zone (LZ) substructures, respectively. While IL21 is known to be important in affinity maturation and GC maintenance, here we show it is required for both establishing normal zone representation and preventing the accumulation of cells in G1 cell cycle stage in the GC LZ. Overall design: Wildtype and IL21 receptor deficient (Il21r-/-) mice were immunized with NP-KLH in alum. Germinal center B cells were extracted from spleens 7 days, 10 days and 14 days after immunization. RNA was extracted and profiled using RNA-seq. An Illumina HiSeq 2000 was used to generate 100bp single-end sequence reads. Each sample was generated from an independent mouse.

体液免疫应答依赖生发中心（Germinal Centres, GC）完成抗体亲和力成熟。在生发中心内部，B细胞增殖与体细胞突变发生于暗区（Dark Zone, DZ），而基于亲和力的阳性选择则定位于亮区（Light Zone, LZ），两类生物学过程彼此相互分隔。尽管已知IL21（白介素21）在抗体亲和力成熟与生发中心维持中发挥重要作用，本研究证实其同时具备两项核心功能：一是维持生发中心正常的分区占比，二是阻止生发中心亮区内细胞在G1细胞周期阶段发生蓄积。
总体实验设计：野生型与IL21受体缺陷型（Il21r-/-）小鼠经明矾佐剂中的NP-KLH（硝基苯基键联钥孔血蓝蛋白）免疫。分别于免疫后第7、10、14天，从小鼠脾脏中分离提取生发中心B细胞。提取总RNA并采用RNA测序（RNA-seq）进行转录组表达谱分析。使用Illumina HiSeq 2000测序平台生成100bp单端测序读段。所有样本均来自独立的个体小鼠。