The germinal center (GC) reaction begins with a diverse and expanded group of B cell clones bearing a wide range of antibody affinities. During GC colonization, B cells engage in long-lasting interactions with T follicular helper (Tfh) cells, a process that depends on antigen uptake and antigen presentation to the Tfh cells. How long-lasting T–B interactions and B cell clonal expansion are regulated by antigen presentation remains unclear. Here, we use in vivo B cell competition models and intravital imaging to examine the adhesive mechanisms governing B cell selection for GC colonization. We find that intercellular adhesion molecule 1 (ICAM-1) and ICAM-2 on B cells are essential for long-lasting cognate Tfh–B cell interactions and efficient selection of low-affinity B cell clones for proliferative clonal expansion. Thus, B cell ICAMs promote efficient antibody immune response by enhancement of T cell help to cognate B cells.

生发中心（GC）反应始于具有广泛抗体亲和力的B细胞克隆的多样化和扩展组。在GC定植期间，B细胞与T滤泡辅助细胞（Tfh）进行持久的相互作用，该过程取决于抗原的摄取和抗原向Tfh细胞的呈递。目前尚不清楚抗原呈递调控多长时间的T–B相互作用和B细胞克隆扩增。在这里，我们使用体内B细胞竞争模型和活体成像来检查控制B细胞选择进行GC定植的粘附机制。我们发现B细胞上的细胞间粘附分子1（ICAM-1）和ICAM-2对于持久的同源Tfh-B细胞相互作用和低亲和力B细胞克隆的有效选择对于增殖性克隆扩增是必不可少的。因此，