During this time, patients were monitored for pulmonary toxicity and 16% were diagnosed with IPS and 11% ultimately diagnosed with BO. Multivariable analysis showed that any RV infection was associated with subsequent development of an alloimmune lung syndrome (P < 0.0001) independent of the type of viral infection. Interestingly the development of acute GVHD was associated with a lower risk of an alloimmune lung syndrome (P 5 0.004), perhaps related to the protective effects of prolonged immunosuppression. Most striking was the finding that development of an alloimmune lung syndrome was the only predictor for mortality (P 5 0.04). Overall survival was 73% for all patients but 53% for patients who developed pulmonary toxicity.