Testing Immunosuppression Threshold in Renal Allografts To Extend eGFR

kSORT assay in pre-established days: 14, 45, 90, 180, 365 and 540 of post transplantation follow-up. If kSORT result is positive maintenance immunosuppressive will be increased (tacrolimus trough levels 12-15 ng/mL, Mofetil Mycophenolate 1.5 mg every 24 hours and prednisone 5 mg/day) and graft biopsy will be obtained. Kidney biopsy will be obtained one mo after treatment as well as kSORT assay. If kSORT result is negative, the maintenance immunosuppressor dosages will remain as established in our institutional guidelines. If after a year of follow-up, the kSORT result is negative, immunosuppression will be decreased (Tacrolimus levels 5 - 10 ng/ml and mofetil mycophenolate 500 mg every 12 hours).

Surveillance will be the usual, includes creatinine determinations and clinical evaluation as often as established in the institutional protocol. A kidney graft biopsy will be obtained in case of dysfunction (increase in serum creatinine \>25% above baseline or 0.3 mg/mL above baseline) or as part of our institutional programmed biopsies (months 3 and 12). Treatment will be established in accordance with biopsy results. In all cases of rejection a kidney biopsy will be obtained one month after initiating treatment. In this control group, samples for kSORT analysis will be collected on pre-established dates for the study, but patient treatment will not be contingent on the assay's results; investigators will be blinded to the result in this control patient group.