This study will examine the safety and effectiveness of a combination kidney and bone marrow transplant from a haplo-identical related donor. An investigational medication and other treatments will be given prior to and after the transplant to help protect the transplanted kidney from being attacked by the body's immune system

Inclusion Criteria:

• Male or female 18-60 years of age
• Candidate for a living-donor renal allograft from an HLA mismatched donor
• First or second transplant with either a living donor or cadaveric transplant as the first transplant.
• Use of FDA-approved methods of contraception by all recipients from the time that study treatment begins until 104 weeks (24 months) after renal transplantation.
• Ability to understand and provide informed consent.
• Serologic evidence of prior exposure to EBV.

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)
• Leukopenia or thrombocytopenia.
• Positive for HIV-1, hepatitis B core antigen, or hepatitis C virus; or positivity for hepatitis B surface antigen.
• Cardiac ejection fraction < 40% or clinical evidence of insufficiency.
• Forced expiratory volume FEV1 < 50% of predicted.
• Lactation or pregnancy.
• 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 membranoprolifertive glomerulonephritis).
• Prior dose-limiting radiation therapy.
• Known genetic disease or family history that may result in greater sensitivity to the effects of irradiation, or a physical deformity that would preclude adequate shielding or appropriate dosing during the irradiation component of the conditioning regimen.
• Enrollment in other investigational drug studies within 30 days prior to enrollment.
• Abnormal (>2 times lab normal) values for (a) liver function chemistries (ALT, AST, AP), (b) bilirubin, (c) coagulation studies (PT, PTT).
• Allergy or sensitivity to any component of belatacept, ATG, tacrolimus, or rituximab.
• Maintenance immunosuppression within 3 months prior to conditioning other than physiological doses of steroids, defined as ≤ 50 mg of hydrocortisone or dose equivalent.
• The presence of any medical condition that the investigator deems incompatible with participation in the trial.

5 years

An adverse event is any occurrence or worsening of an undesirable or unintended sign, symptom, laboratory finding, or disease that occurs during participation in the trial.

An adverse event will be followed until it resolves or until 30 days after a participant terminates from the study, whichever comes first.

The incidence of adverse events found around 10 days after bone marrow transplant.