Vaccination and infection promote the formation, tissue distribution, and clonal evolution of B cells, which encode humoral immune memory. We evaluated pediatric and adult blood and deceased adult organ donor tissues to determine convergent antigen-specific antibody genes of similar sequences shared between individuals. B cell memory varied for different pathogens. Polysaccharide antigen–specific clones were not exclusive to the spleen. Adults had higher clone frequencies and greater class switching in lymphoid tissues than blood, while pediatric blood had abundant class-switched convergent clones. Consistent with reported serology, prepandemic children had class-switched convergent clones to severe acute respiratory syndrome coronavirus 2 with weak cross-reactivity to other coronaviruses, while adult blood or tissues showed few such clones. These results highlight the prominence of early childhood B cell clonal expansions and cross-reactivity for future responses to novel pathogens.

疫苗接种和感染会促进B细胞的形成，组织分布和克隆进化，而B细胞编码体液免疫记忆。我们评估了儿科和成年血液以及已故的成年器官供体组织，以确定在个体之间共享的相似序列的会聚抗原特异性抗体基因。B细胞记忆因不同的病原体而异。多糖抗原特异性克隆并非仅局限于脾脏。成人比血液具有更高的克隆频率和更大的淋巴组织类别转换，而儿科血液具有丰富的类别转换会聚克隆。与报道的血清学一致，大流行前儿童的类转换趋同克隆为严重的急性呼吸系统综合症冠状病毒2，与其他冠状病毒的交叉反应性较弱，而成人血液或组织中几乎没有此类克隆。