Lung immunogenicity, rejection, and obliterative bronchiolitis.

Evidence suggests that obliterative bronchiolitis (OB) following human heart-lung transplantation is a form of allograft rejection related to augmented expression of class II major histocompatibility complex antigens (MHCII) on airway epithelium and mediated by activated T cells. Other forms of OB, including those related to viral infection and autoimmune disease, may reflect a similar mechanism.