Acute GVHD results in a severe DC defect that prevents T-cell priming and leads to fulminant cytomegalovirus disease in mice

Matthew E Wikstrom, Peter Fleming, Rachel D Kuns, Iona S Schuster, Valentina Voigt, Gregory Miller, Andrew D Clouston, Siok-Keen Tey, Christopher E Andoniou, Geoffrey R Hill, Mariapia A Degli-Esposti

Viral infection is a common, life-threatening complication after allogeneic bone marrow transplantation (BMT), particularly in the presence of graft-versus-host disease (GVHD). Using cytomegalovirus (CMV) as the prototypic pathogen, we have delineated the mechanisms responsible for the inability to mount protective anti-viral responses in this setting. While CMV infection was self-limiting after syngeneic BMT, in the presence of GVHD after allogeneic BMT, CMV induced a striking cytopathy resulting in universal mortality in conjunction with a fulminant necrotizing hepatitis. Critically, GVHD induced a profound DC defect that led to a failure in the generation of CMV-specific CD8(+) T cell responses. This was accompanied by a defect in anti-viral CD8(+) T cells. In combination, these defects dramatically limited anti-viral T cell responses. The transfer of virus-specific cells circumvented the DC defects and provided protective immunity, despite concurrent GVHD. These data demonstrate the importance of avoiding GVHD when reconstructing anti-viral immunity after BMT, and highlight the mechanisms by which the adoptive transfer of virus-specific T cells overcome the endogenous defects in priming invoked by GVHD.