Enhancing Graft vs Leukemia Via Delayed Ex-Vivo Co-Stimulated DLI After Non-Myeloablative Stem Cell Transplantation

Patient-related Parameters: * Patients must have a healthy histocompatible donor (A, B and DR match); either sibling or unrelated volunteer identified through the NMDP * Age between 18 and 70 years old * Life expectancy greater than 3 months. * ECOG performance status 0-1. * Patients must have acceptable organ function: * total bilirubin \<2.0 * AST and ALT \< 3 x normal, unless increases are thought to be either from non-hepatic causes (i.e hemolysis) or related to underlying disease (such as liver involvement with leukemia); * creatinine \<2.0 or creatinine clearance \>40 ml/min (calculated or collected); * Cardiac: An ejection fraction \>40% on MUGA or echocardiogram; * Pulmonary: corrected DLCO \>50% Exclusion Criteria: Subjects: * Patients who have had chemotherapy or radiotherapy within 4 weeks prior to entering the study. Patients must have recovered from adverse events due to agents administered more than 4 weeks earlier. * Patients with uncontrolled or untreated central nervous system involvement * Patients with uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * HIV positive patients are excluded * Pregnant women * Patients who are breastfeeding Donors: * Sibling donors will be evaluated according to the standard practice of the University of Pennsylvania Bone Marrow and Stem Cell Transplant Program * Unrelated donor evaluations and consent will be performed by an NMDP donor center according to standard guidelines and procedures.