Shared B cell memory to coronaviruses and other pathogens varies in human age groups and tissues

Yang, Fan; Nielsen, Sandra C. A.; Hoh, Ramona A.; Lee, Ji-Yeun; Pham, Tho D.; Jackson, Katherine J. L.; Roskin, Krishna M.; Liu, Yi; Ohgami, Robert S.; Osborne, Eleanor M.; Niemann, Claus U.; Parsonnet, Julie; Boyd, Scott D.

Vaccination and infection promote the formation, tissue distribution, and clonal evolution of B cells encoding humoral immune memory. We evaluated convergent antigen-specific antibody genes of similar sequences shared between individuals in pediatric and adult blood, and deceased organ donor tissues. B cell memory varied for different pathogens. Polysaccharide antigen-specific clones were not exclusive to the spleen. Adults’ convergent clones often express mutated IgM or IgD in blood and are class-switched in lymphoid tissues; in contrast, children have abundant class-switched convergent clones in blood. Consistent with serological reports, pre-pandemic children had class-switched convergent clones to SARS-CoV-2, enriched in cross-reactive clones for seasonal coronaviruses, while adults showed few such clones in blood or lymphoid tissues. These results extend age-related and anatomical mapping of human humoral pathogen-specific immunity. One Sentence Summary Children have elevated frequencies of pathogen-specific class-switched memory B cells, including SARS-CoV-2-binding clones.