Chapter 16 - The Cellular Basis of B Cell Memory

Abstract

This chapter describes mechanisms of (true) immunological memory in the humoral immune system of a mouse and a human. They are based on two specific modes of cellular differentiation, the first resulting in the generation of long-lived and antigen-independent memory cells that respond to renewed antigenic challenge by the rapid differentiation into plasma cells and production of secreted antibodies. While the other generates a compartment of long-lived plasma cells dedicated to long-term antibody production, independent of sustained antigenic challenge. Both types of cells are selected in the germinal center reaction for the production of high-affinity antibodies resulting from somatic hypermutation of rearranged antibody variable region genes. Both memory and long-lived plasma cells are generated, and later reside in defined cellular microenvironments, whose integrity is critical for the survival of the cells. Upon antigenic re-encounter, memory cells recruit T cell's help through efficient antigen presentation, which in turn drives their expansion and terminal differentiation and thus replenish the plasma cell pool.