Maintenance of serological memory.

Long-lived plasma cells are key to maintaining long-term humoral immunity after infection or vaccination. Some vaccines and/or infections induce antibody levels that remain stable for the life of the individual. However, the mechanism whereby these long-lived plasma cells are maintained over long periods of time remains an open question. Furthermore, given a finite number of sustainable plasma cells within the bone marrow, it is also unclear how space for newly induced plasma cells is generated without compromising the pre-existing repertoire. Here we review the current understanding of these important issues.