Graft-versus-host disease: the need for a new terminology.

For some decades, graft-versus-host (GVH) reactions seemed readily comprehensible. It was generally accepted that after introduction of immunocompetent, histoincompatible lymphocytes into an immunodeficient host the grafted lymphocytes would start a 'rejection' response against their host. As a result, GVH disease developed. Acute disease might result in death and survivors became chimaeras with varying pathology--chronic GVH disease. In recent years, however, some intriguing exceptions to the general rules for the development of GVH disease have been reported. These exceptions, particularly the activation of GVH disease by stimuli other than histocompatibility barriers prompted Gerard Bos and colleagues to propose this change in terminology.