Development of B-cell memory in early childhood and the impact on antigen-specific tolerance after heart transplantation

CD27+ cells play a key role in T-independent B-cell activation. Response to ABH antigens is mediated by IgM+CD27+ B cells, and donor ABO-specific tolerance after ABO-incompatible transplantation in children is facilitated by low prevalence of these cells. The pattern of B-cell memory development is altered after ABO-incompatible transplant. Memory B cells may be quantified to assess eligibility for ABO-incompatible transplant and represent a potential therapeutic target to extend the benefits of the immature immune system to older age groups.