PLC-gamma2 is essential for formation and maintenance of memory B cells.

Resting antigen-experienced memory B cells are thought to be responsible for the more rapid and robust antibody responses after antigen reencounter, which are the hallmark of memory humoral responses. The molecular basis for the development and survival of memory B cells remains largely unknown. We report that phospholipase C (PLC) gamma2 is required for efficient formation of germinal center (GC) and memory B cells. Moreover, memory B cell homeostasis is severely hampered by inducible loss of PLC-gamma2. Accordingly, mice with a conditional deletion of PLC-gamma2 in post-GC B cells had an almost complete abrogation of the secondary antibody response. Collectively, our data suggest that PLC-gamma2 conveys a survival signal to GC and memory B cells and that this signal is required for a productive secondary immune response.