B Cell Activating Factor, Renal Allograft Antibody-Mediated Rejection, and Long-Term Outcome

Figure 2

Expression of BAFF-R, BCMA, and TACI on B cells at different stages of development and activation. (a) BAFF-R begins to be expressed at the late transitional stage and is present on all mature B cells. Its expression is reduced on B cell entry into the GC reaction and is reexpressed on memory B cells but absent on plasmablasts and plasma cells. (b) TACI expression can be detected after the late transitional stage and also on plasmablasts and plasma cells. (c) BCMA expression is restricted to plasmablasts and plasma cells. (d and e) BAFF promotes the maturation of transitional B cells and the subsequent survival of mature B cells, whereas BAFF and APRIL can both promote plasma cell survival. Memory B cell survival and reactivation are independent of BAFF or APRIL signaling. (f) BAFF-R signals interplay with BCR signals in determining B cell maturation and survival. Under conditions of limiting BAFF availability, ligation of the BCR by antigen leads to anergy and reduced lifespan in immature transitional B cells.