Interstitial pneumonitis following bone marrow transplantation: pathogenesis and therapeutic considerations.

High-dose chemo-radiotherapy followed by allogeneic bone marrow transplantation has become standard treatment for a variety of hematological malignancies. Interstitial pneumonitis (IP) is a major complication after bone marrow transplantation, the incidence being approximately 50% (range 20-65%). Cytomegalovirus (CMV) is found in about half of these cases. If no infectious cause can be detected, the interstitial pneumonitis is labeled 'idiopathic'. The occurrence of CMV IP is related to the state of severe immunosuppression in combination with graft-vs-host disease (GvHD) in these patients. The most important factors contributing to idiopathic IP seem to be: chemotherapy, total-body irradiation, agents to prevent GvHD and GvHD itself. For preventing CMV IP hyperimmune globulin seems to be the most promising method at this moment. As long as the etiology of idiopathic IP remains unclear, no measures can be taken to prevent or treat this disease.