Mechanisms of action of extracorporeal photochemotherapy in the control of GVHD: involvement of dendritic cells.

Despite the fact that extracorporal photochemotherapy (ECP) is now broadly used for the treatment of graft versus host disease or T-cell lymphomas, the mechanisms of its action remain enigmatic. This work provides a synthesis of the main results suggesting the initiation by ECP of an immune reaction responsible for the down modulation of pathogenic T-cell functions, with a special focus on the role of dendritic cells in this phenomenon.