INTRODUCTION

Graft-versus-host disease (GVHD) is a complication usually associated with allogenic bone marrow transplantation, occurring in 40–80% of recipients. Rarely, GVHD can develop subsequent to solid organ transplantation, particularly after liver and small-bowel transplantation. It has been reported to occur in 1.2% (12/1082) to 1.5% (7/453) in two series of liver transplant recipients and 4.7% (6/128 adults) to 6.5% (8/122 children) of small-bowel transplant recipients. GVHD is rare after cardiac, lung, and renal transplantation, having been reported in only 2 heart/lung transplant patients, 4 lung transplant patients, and 1 kidney transplant patient. This chapter will focus on GVHD, which occurs in solid organ transplant recipients.

PATHOGENESIS

For GVHD to occur, donor tissue containing immunocompetent T cells must be placed into an immunocompromised recipient possessing tissue antigens otherwise absent from the donor. The pathogenesis of GVHD is initiated prior to transplantation with damage to host tissue caused by underlying illness, therapeutic intervention, infection, or pretransplant conditioning. These insults can lead to host antigen presenting cell activation and release of tumor necrosis factor alpha, interleukin-1, and interleukin-6. Once the transplant occurs, these factors facilitate activation of donor T cells transferred with the allograft, which differentiate into T-helper 1 cells that secrete interferon-gamma and interferon-2. The net result of these events is activation of cytotoxic T cell lymphocytes, natural killer cells, and macrophages that attack host cells, primarily in the skin.