Immunological memory is required for protection against repeated infections and is the basis of all effective vaccines. Antibodies produced by memory B cells play an essential role in many of these responses. We have combined lineage tracing with antibody cloning from single B cells to examine the role of affinity in B cell selection into germinal centers (GCs) and the memory B cell compartment in mice immunized with an HIV-1 antigen. We find that contemporaneously developing memory and GC B cells differ in their affinity for antigen throughout the immune response. Whereas GC cells and their precursors are enriched in antigen binding, memory B cells are not. Thus, the polyclonal memory B cell compartment is composed of B cells that were activated during the immune response but whose antigen binding affinity failed to support further clonal expansion in the GC.

免疫记忆是防止反复感染所必需的，并且是所有有效疫苗的基础。记忆 B 细胞产生的抗体在许多这些反应中起着至关重要的作用。我们将谱系追踪与单个 B 细胞的抗体克隆相结合，以检查亲和力在 B 细胞选择进入生发中心 (GC) 和免疫 HIV-1 抗原的小鼠的记忆 B 细胞区室中的作用。我们发现同时发育的记忆和 GC B 细胞在整个免疫反应中对抗原的亲和力不同。GC 细胞及其前体富含抗原结合，而记忆 B 细胞则不然。因此，