One-two punch injury to tolerance mechanisms in graft-versus-host disease.

Chronic graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplantation that resembles autoimmunity, with unclear pathogenesis and few effective therapeutic options. In this issue of the JCI, Dertschnig et al. used mouse models to investigate the basis of T cell autoreactivity following GVHD. Notably, GVHD caused irreversible damage to a population of tolerogenic stromal cells that display peripheral tissue-restricted antigens in lymph nodes, which impaired their capacity to purge and suppress autoreactive T cells. Together with damage to central tolerance mechanisms in the thymus, these findings outline a critical one-two punch injury that profoundly disrupts immune tolerance in this devastating disease.