Does graft-versus-host disease attack epithelial stem cells?

Graft-versus-host disease (GvHD) is the opposite of graft rejection in that a transplant containing donor lymphocytes attacks the host's skin, liver and gut. This disease can usefully also attack host tumor cells. There is a peculiar distribution of normal tissue targets in epithelial stem cell sites, suggesting that GvHD may be the abnormal counterpart of a physiological growth control system. Efforts to understand how the graft-versus-tumor effect could be therapeutically separated from GvHD require further understanding of the mechanisms involved in GvHD.