Proposed scheme of B-cell activation with BAFF in GCs. GC B cells receive signals for activation by FDCs through the BCR and B-cell coreceptor complex. The B-cell responses are further enhanced by BAFF providing CD19 and probable BLNK up-regulation through Pax5 activation and the high ability of BCR to phosphorylate CD19, which in turn amplifies BCR signaling. Moreover, up-regulation of CD40 by BAFF renders the same B cells more susceptible to T-cell help by CD154. See “Discussion” for details.