 This is a randomized, open-label, pilot intervention trial. Post transplant patients with deteriorating renal function defined as 20 reduction in GFR will be screened for the development of DSA and biopsied for the presence of C4d deposition. All patients with DSA and those meeting inclusionexclusion criteria will undergo protocol renal biopsy and will be assessed for C4d deposition. Participants will be randomized to treatment with eculizumab plus standard of care SOC or SOC only. Randomization will be stratified by C4d status C4dC4d- with 10 subjects 7 eculizumab, 3 SOC only in each stratum. 