Patients undergo bronchoscopy with bronchoalveolar lavage (BAL) prior to allogeneic hematopoietic stem cell transplantation (HSCT). ELISA assays for cytokines are performed. Patients are followed post-HSCT for the development of transplant related pulmonary complications. A repeat bronchoscopy with BAL is performed at the time pulmonary complications develop or at day 60 post-HSCT if no complications develop. Cytokine assays are repeated.