Memory B cells: total recall

- Multiple subsets of memory B cells exist, with distinct functions and developmental requirements.
- Human IgM+CD27+ memory B cells require innate signalling to form but germinal centres for re-modelling.
- Class-switched memory B cells require CD4+ T cell help and GC for their generation and maintenance.
- Memory B cells localise to distinct anatomical sites, according to isotype and site of activation.
- Memory B cell generation is controlled by transcriptional networks.

Immunological memory is a cornerstone of adaptive immune responses in higher vertebrates. The remarkable ability to generate memory cells following Ag exposure, in the context of natural infection or immunization, provides long-lived protection against infectious diseases, often for the hosts' lifetime. Indeed, the generation of memory B cells and long-lived plasma cells underpins the success of most vaccines. The concept of immunological memory is not new-it was first proposed nearly 2500 years ago. While our understanding of the complexities of humoral and cell-mediated memory continues to evolve, important aspects of this process remain unresolved. Here, we will provide an overview of recent advances in B-cell memory in mice and humans, and in health and disease.