Extracorporeal photopheresis: a review

Extracorporeal phototherapy (ECP) is a therapeutic approach based on the bi ological effect of psoralen 8-methoxypsoralen (8-MOP) and ultraviolet light A (UVA) on mononuclear cells collected by apheresis, and reinfused into the patient. Photopheresis is widely used for the treatment of patients with a dvanced cutaneous T-cell lymphoma (CTLC). Evidence suggests that it prolong s life, and also induces 50-75% response rates. In addition, more and more reports indicate that photopheresis is a potent agent in the therapy of acu te allograft rejection among cardiac, lung and renal transplant recipients. There are increasing amounts of data showing that patients with chronic gr aft versus host disease benefit from this therapy. Likewise, there are indi cations that there may be a potential role for ECP in the therapy of certai n autoimmune diseases resistant to conventional therapy. The mechanism of t his treatment is likely due to the induction of anticlonotypic immunity dir ected against pathogenic clones of T lymphocytes. Treatment induces apoptot ic death of pathogenic T-cells, and it is postulated that activation of ant igen-presenting cells has important effects in this process. (C) 2001 Harco urt Publishers Ltd.