Extracorporeal photopheresis: clinical use so far.

Extracorporeal photopheresis (ECP or photopheresis) is an advanced therapeutic apheresis procedure in which blood is separated into its various components and the isolated buffy coat is treated with 8-methoxypsoralen (a photoactivating drug), exposed to ultraviolet light and returned to the patient. All other remaining blood components are also returned to the patient. The purpose of this procedure is immunomodulation. The treated leukocytes, specifically T-cells, are returned to the patient's circulation and will induce cytotoxicity and reduce proliferation of new T-cells. In the United States, ECP was initially approved for the treatment of cutaneous T-cell lymphoma by the US Food and Drug Administration in the late 1980s. Since that time, it has been used as an "off-label" therapy to treat several other autoimmune diseases in the United States and even more extensively in Europe and Asia. The following review is limited to the current clinical use of ECP in cutaneous T-cell lymphoma, Crohn's disease, systemic sclerosis, graft versus host disease, and emerging data on nephrogenic systemic fibrosis.