Viral particles drive rapid differentiation of memory B cells into secondary plasma cells producing increased levels of antibodies.
Zabel F., Mohanan D., Bessa J., Link A., Fettelschoss A., Saudan P., Kündig TM., Bachmann MF.
Extensive studies have been undertaken to describe naive B cells differentiating into memory B cells at a cellular and molecular level. However, relatively little is known about the fate of memory B cells upon Ag re-encounter. We have previously established a system based on virus-like particles (VLPs), which allows tracking of VLP-specific B cells by flow cytometry as well as histology. Using allotype markers, it is possible to adoptively transfer memory B cells into a naive mouse and track responses of naive and memory B cells in the same mouse under physiological conditions. We have observed that VLP-specific memory B cells quickly differentiated into plasma cells that drove the early onset of a strong humoral IgG response. However, neither IgM(+) nor IgG(+) memory B cells proliferated extensively or entered germinal centers. Remarkably, plasma cells derived from memory B cells preferentially homed to the bone marrow earlier and secreted increased levels of Abs when compared with primary plasma cells derived from naive B cells. Hence, memory B cells have the unique phenotype to differentiate into highly effective secondary plasma cells.