Renal Allograft Tolerance Through Mixed Chimerism

Key Inclusion Criteria: * Male or female 18-60 years of age * Candidate for a living-donor renal allograft with a one haplotype identical donor identified. * First or second transplant with either a living donor or cadaveric transplant as the first transplant. * Positive serologic testing for EBV indicating past exposure. Key Exclusion Criteria: * ABO blood group-incompatible renal allograft. * Evidence of anti-HLA antibody within 60 days prior to transplant as assessed by routine methodology (AHG and/or ELISA) * Positive testing for: HIV, hepatitis B core antigen, or hepatitis C virus or positivity for hepatitis B surface antigen. * Cardiac ejection fraction \< 40% or clinical evidence of insufficiency. * History of cancer other than basal cell carcinoma of the skin or carcinoma in situ of the cervix. * Underlying renal disease etiology with a high risk of disease recurrence in the transplanted kidney (such as focal segmental glomerulosclerosis, type I or II nonproliferative glomerulonephritis). * Prior dose-limiting radiation therapy. * Abnormal (\>2 times lab normal) values for (a) liver function chemistries (ALT, AST, AP), (b) bilirubin, (c) coagulation studies (PT, PTT). * The presence of any medical condition that the investigator deems incompatible with participation in the trial.