Tomohiro Kurosaki: "Unique Properties of Memory B Lymphocytes"

Tomohiro Kurosaki
Lab of Lymphocyte Differentiation, WPI Immunology Frontier Research Center, Osaka University, Osaka and RCAI, RIKEN, Yokohama

Unique Properties of Memory B Lymphocytes

Understanding the mechanism by which memory B cells are generated and maintained, as well as defining the basis of their heightened responsiveness, is of fundamental inter-est to reveal the basis of immunological memory.
In terms of location of memory B cells, we have recently shown that NP-CGG-induced IgG1 type memory B cells resided adjacent to waned germinal centers (GCs) in the spleen. Since we also observed that CD4+ T cells existed in close proximity to IgG1 memory B cells, we would propose that this close proximity of memory IgG1 B cells to memory T cells can explain, at least partly, the more rapid kinetics of humoral memory responses.
In terms of longevity of memory B cells, we found that IgG1 type memory B cell homeo-stasis was severely hampered by inducible deletion of PLCy2. Based on these observa-tions, together with in vitro analysis, we would like to propose that a BCR signal, pre-sumably similar to that needed for the survival of naïve B cells, is required for mainte-nance of IgG1 type memory B cells, and that this survival signal is mediated by PLCy2.