Graft-versus-host disease.

Graft-versus-host disease, both acute and chronic, continues to be the major complication of human bone marrow transplantation. Improved posttransplant chemoprophylaxis has reduced the incidence of acute graft-versus-host disease, but the incidence of the chronic form of the disease remains unchanged. The use of donors that are not genotypically identical at the major histocompatibility complex increases the incidence of acute and chronic graft-versus-host disease. The clinical consequences of acute and chronic graft-versus-host disease are discussed.