<qa>  What is the technique used to expose peripheral white blood cells to?ECP is a technique in which peripheral white blood cells are exposed to a photoactivatable compound UVADEX administered extracorporeally and ultraviolet A light. After cells are reinfused into the patient, their function is altered, thereby activating mechanisms that allow for further regulation of specific lymphocyte populations. ECP has shown activity in several inflammatory and autoimmune diseases, including scleroderma, rheumatoid arthritis, transplantation rejection, acute and chronic GvHD. 