As viral complications in these patients are clearly associated with the lack of recovery of virus-specific cellular immune responses, reconstitution of the host with in vitro expanded CTLs is an effective approach to prevent and treat these diseases. Adoptive immunotherapy with in vitro expanded CTLs has proved effective in preventing and treating diseases related to Epstein Barr virus (EBV) infections 5; 6 and cytomegalovirus (CMV) reactivations7 in hematopoietic stem cell transplant (HSCT) recipients. A promising strategy to generate donor-derived Ad-specific CTL is the infection of monocytes that direct the CTL response to viral capsid antigens8. This approach allows exposure to all proteins in the Ad protein coat, leading to presentation of multiple, undefined antigen epitopes. Hence, the investigators now plan to use a recombinant Ad vector for infection of donor-derived monocytes. These infected monocytes will then be used as antigen presenting cells (APC) to generate Ad-specific CTL in vitro. For the expansion of the Ad-specific CTL, the second stimulation will use irradiated, Ad-infected monocytes and subsequent stimulations will use donor-derived Lymphoblastoid Cell Lines (LCL) transduced with the Ad vector as an APC 9.