Immune Disease Institute and Program in Molecular and Cellular Medicine, Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, 02115 MA, USA.
Immunity. 2012 Aug 24;37(2):199-207. doi: 10.1016/j.immuni.2012.08.002.
The complement system of innate immunity is important in regulating humoral immunity largely through the complement receptor CR2, which forms a coreceptor on B cells during antigen-induced activation. However, CR2 also retains antigens on follicular dendritic cells (FDCs). Display of antigen on FDCs is critical for clonal selection and affinity maturation of activated B cells. This review will discuss the role of complement in adaptive immunity in general with a focus on the interplay between CR2-associated antigen on B cells with CR2 expressed on FDCs. This latter interaction provides an opportunity for memory B cells to sample antigen over prolonged periods. The cocrystal structure of CR2 with its ligand C3d provides insight into how the complement system regulates access of antigen by B cells with implications for therapeutic manipulations to modulate aberrant B cell responses in the case of autoimmunity.
补体系统在调节体液免疫中起着重要作用，主要通过补体受体 CR2 实现，该受体在抗原诱导的 B 细胞激活过程中形成 B 细胞的辅助受体。然而，CR2 也能在滤泡树突状细胞（FDC）上保留抗原。FDC 上抗原的展示对于激活 B 细胞的克隆选择和亲和力成熟至关重要。本综述将讨论补体在适应性免疫中的一般作用，重点是 B 细胞上与 CR2 相关的抗原与 FDC 上表达的 CR2 之间的相互作用。这种相互作用为记忆 B 细胞提供了长时间采样抗原的机会。CR2 与其配体 C3d 的共晶结构提供了关于补体系统如何调节 B 细胞获得抗原的见解，这对治疗性操纵具有重要意义，可以调节自身免疫情况下异常 B 细胞反应。
