Figure 2.

After conditioning by tissue-derived factors and TLR ligands, DCs activate T cells which provide for costimulatory signals (CD40-CD40L) and specific cytokines (TD), or DCs provide for alternative costimulatory signals, like BAFF and APRIL (TI) to initiate class switch recombination and expression of IgA by the mature B cells (IgA⁺ B cell). From the inductive site, the IgA⁺-B cells will migrate to the draining effector sites, where, in response to additional signals, they become plasma cells (PCs) and start to secrete IgA.