Memory B cell survival and function in the absence of secreted antibody and immune complexes on follicular dendritic cells.

Ag, in the form of immune complexes retained on follicular dendritic cells, has been implicated in the development and maintenance of B cell memory. We addressed this question using a H chain transgenic (Tg) mouse model that lacks secreted Ig (mIg), and thus does not deposit Ag-containing immune complexes. We compared the ability of the mIg strain and a control Tg strain, which secretes IgM, to develop and maintain long-lived memory cells. After immunization, there was an increase of Ag-specific B cells in both strains that was maintained for at least 20 wk. We labeled the long-lived Ag-specific cells with BrdU and found that this population was similarly maintained. In addition, both Tgs were able to maintain a functional memory response as measured by secondary germinal center reactions. Our studies indicate that localization of Ag on follicular dendritic cells is not necessary for development and maintenance of B cell memory.