Bronchiolitis obliterans syndrome (BOS) is a form of chronic lung allograft dysfunction that
affects a majority of lung transplant recipients and is the principal factor limiting long-term
transplant survival. BOS is characterized by progressive airflow obstruction unexplained by
acute rejection, infection, or other coexistent condition. Although BOS is a proven useful
clinical syndrome that identifies patients at increased risk for death, its clinical course and
underlying causative factors are now recognized to be increasingly heterogeneous …