Photopheresis Those who have skin conditions associated with advanced cutaneous T-cell lymphoma (CTCL) and possibly those with autoimmune diseases, graft-vs-host disease (GvHD), or solid organ transplant rejection problems may benefit from photopheresis treatment. The apheresis machine separates some white blood cells from the rest of the blood and adds methoxsalen, a photoactive chemical, to the separated white blood cells. The rest of the blood returns to the patient. The white blood cells that were treated with methoxsalen are exposed to ultraviolet light and then return to the patient. The treated white blood cells are believed to stimulate the host immune system and help the body control the cells that contribute to the disease. The James P. Wilmot Cancer Center has one of the leading centers in the nation for adult and pediatric blood and marrow transplantation.