Human anti-glycan reactivity emerges from B cells utilizing private gene rearrangements that are affinity maturated in germinal centers

The human antibody repertoire includes reactivity toward a broad array of carbohydrate antigens associated with commensal microflora and pathogenic organisms. Here, we examined the ontogeny and diversity of the human anti-glycan repertoire. Antibodies reactive with group A Streptococcus cell wall carbohydrate (GAC) were absent at birth but reached adult frequencies in childhood, concomitant with the emergence of circulating GAC-reactive memory B cells. GAC-binding B cells expressing germinal cen