Transient reduction in IgA⁺ and IgG⁺ memory B cell numbers in young EBV-seropositive children: the Generation R Study

The EBV is known to persist in memory B cells, but it remains unclear how this affects cell numbers and humoral immunity. We here studied EBV persistence in memory B cell subsets and consequences on B cell memory in young children. EBV genome loads were quantified in 6 memory B cell subsets in EBV⁺ adults. The effects of EBV infection on memory B cell numbers and vaccination responses were studied longitudinally in children within the Generation R population cohort between 14 mo and 6 yr of age. EBV genomes were more numerous in CD27⁺IgG⁺, CD27⁺IgA⁺, and CD27^-IgA⁺ memory B cells than in IgM-only, natural effector, and CD27^-IgG⁺ B cells. The blood counts of IgM-only, CD27⁺IgA⁺, CD27^-IgG⁺, and CD27⁺IgG⁺ memory B cells were significantly lower in EBV⁺ children than in uninfected controls at 14 mo of age-the age when these cells peak in numbers. At 6 yr, all of these memory B cell counts had normalized, as had plasma IgG levels to previous primary measles and booster tetanus vaccinations. In conclusion, EBV persists predominantly in Ig class-switched memory B cells, even when derived from T cell-independent responses (CD27^-IgA⁺), and EBV infection results in a transient depletion of these cells in young children.