Zapping Wayward Cells: Therapy sheds light on transplant complication
By Nathan Seppa
Doctors sometimes recommend ultraviolet (UV) light exposure for people suffering from complications of a bone marrow transplant from a donor. The radiation can ameliorate skin lesions, such as rashes and ulcers, that are a common side effect of the procedure. But UV radiation isn’t a standard treatment, in part because its mechanism of action is unknown and no large-scale study has established its effectiveness.
An experiment in which mice received marrow transplants now suggests that UV light wipes out troublemaking immune cells of the skin. Earlier research had suggested that these Langerhans cells react with immune cells derived from the transplant and cause graft-versus-host disease (GVHD), a dangerous complication in which donor immune cells attack the skin, liver, and gut. In the mouse experiment, by hematologist Miriam Merad of the Mount Sinai School of Medicine in New York and her colleagues at several institutions, UV-light exposure before the transplantation prevented GVHD.