Immunologic consequences of transplantation.

With current immunosuppressive regimens, rejection is common after lung transplantation. Acute rejection is usually easily reversible with therapy, but chronic rejection often responds poorly and is the leading cause of late morbidity and mortality. Although the pathogenesis of chronic rejection is not fully understood and might be different from ACR, the studies summarized in this review support the concept that alloimmune responses are of fundamental importance. Acute rejection and infection, particularly with CMV, appear to promote changes within the allograft that increase the risk of chronic rejection. Although the progression of OB in some patients might be arrested with immunosuppression, a large percentage of patients with OB suffer from a continuous loss of lung function. Improvement in the long-term outcome of lung transplant recipients will require both better immunosuppressive agent and more specific therapy such as induction of donor-specific tolerance.