In a new animal study, researchers identified the principal culprit in GVHD: an immune cell in the skin known as a Langerhans cell. These cells normally function as flag posts for the immune system, signaling infection-fighting T-cells to come to a particular site to fight off a virus or bacteria. But in transplants, they do patients a great disservice, alerting T-cells to attack the patient's own tissues, researchers found.
The researchers were able to effectively eliminate the Langerhans cells in transplanted mice by exposing them to ultraviolet light, giving the animals mild sunburn. Transplanted mice that received this treatment experienced no GVHD while those that didn't showed severe signs of the disease, said Edgar Engleman, MD, professor of pathology and medicine and senior author of the study.
"The experiment not only provided the proof that these cells cause graft-versus-host disease, but also provides a way of thinking about how you might prevent it," said Engleman, who also directs the Stanford Blood Center. The study appears in the May issue of the journal Nature Medicine.
Bone marrow or stem cell transplants are commonly used to treat patients with cancers of the blood system, such as leukemia, lymphoma or myeloma. Patients first receive radiation treatment to wipe out their defective immune systems, which then are replaced by healthy donor cells.
Sometimes, however, the process fails as GVHD sets in. The effects of the disease are most commonly seen in the skin as a reddish rash or, in more s
Contact: Ruthann Richter
Stanford University Medical Center