Depletion Induction With Rabbit Anti-Thymocyte Globulin, Followed by Two Approaches Toward Monotherapy Immunosuppression in Kidney Transplant Recipients

* INCLUSION CRITERIA: Candidates for a kidney transplant at the Clinical Center. Willingness and legal ability to give informed consent. Availability of donor tissue for testing. This could include splenic or peripheral blood lymphocytes from a cadaveric donor or a willing living donor who consents to periodic phlebotomy for peripheral blood lymphocyte isolation. EXCLUSION CRITERIA: Immunosuppressive drug therapy at the time of or 2 months prior to enrollment. Specifically, candidates may not be taking prednisone, cyclosporine, tacrolimus, azathioprine, mycophenolate mofetil, anti-lymphocyte agents, cyclophosphamide, methotrexate, or other agents whose therapeutic effect is immunosuppressive. Any active malignancy or any history of any hematogenous malignancy or lymphoma. Patients with primary, cutaneous basal cell or squamous cell cancers may be enrolled providing the lesions are appropriately treated prior to transplant. Any known immunodeficiency syndrome, or other condition that, in the opinion of the investigators, would likely increase the risk of protocol participation or confound the interpretation of the data. Any history of sensitization to rabbits or extensive exposure to rabbits, as defined by symptomatic allergic response upon exposure to rabbits. Inability or unwillingness to comply with protocol monitoring and therapy including, among others, a history of noncompliance, circumstances where compliance with protocol requirements is not feasible due to living conditions, travel restrictions, access to urgent medical services, or access to anti-rejection drugs after the research protocol is completed. Peak Panel Reactive Antibody greater than 20%, or historically positive crossmatch due to HLA (human leukocyte antigen)-specific antibodies. HLA (human leukocyte antigen) identity between the donor and recipient. Pregnancy or unwillingness to practice an approved method of birth control. Acceptable methods of birth control may include barrier methods (condom and/or diaphragm with spermicide), oral contraceptives, Norplant, Depo-Provera or partner sterility.