Acute Allograft Rejection: Cellular and Humoral Processes

Martinu, Tereza; Pavlisko, Elizabeth N; Chen, Dong-Feng; Palmer, Scott M.

Acute cellular rejection affects greater than a third of lung transplant recipients. Alloreactive T lymphocytes, responding directly or indirectly to donor antigen, constitute the basis of lung allograft rejection, as diagnosed by well-established histopathological criteria that reflect the severity of perivascular or peribronchial inflammation in the lung allograft. Recent evidence supports a more complex immune response to the allograft with involvement of humoral mechanisms, characterized by circulating antibody to donor HLA and specific patterns of lung injury, occurring in parallel with T cell-based rejection. Emerging evidence further suggests that the interaction between recipient genetics, immunosuppression therapies, and allograft environmental exposures, including pulmonary infection, contributes to high rejection rates after lung transplantation. A greater understanding of the heterogeneous mechanisms of lung rejection is critical to developing effective therapies that target the precise pathophysiology of the disease and ultimately improve long-term lung transplant outcomes.