C1796 Immune Phenotyping and Efficacy of Low Dose ATG in NonSensitized Kidney Recipients Undergoing Early Steroid Withdrawal: A Randomized Pilot Study. B. Smith,1 M. Grafals,2 N. Murakami,1 A. Trabucco,2 K. Hamill,2 E. Marangos,2 H. Gilligan,2 J. Pomposelli,2 E. Pomfret,2 J. Azzi,1 N. Najafi an,1 L. Riella.1 1Transplantation Research Center, Renal Division, Brigham & Women’s Hospital, Harvard Medical School, Boston, MA; 2Department of Transplant Surgery, Lahey Clinic Medical Center, Burlington. Rabbit antithymocyte globulin (ATG) is commonly used as an induction agent in renal transplant recipients, but the ideal dosage in tacrolimus-based early steroid withdrawal protocols has not been established. The purpose of this pilot study was to determine the safety and effi cacy of lower dose ATG as induction therapy in low immunological-risk kidney transplant recipients. In this prospective study, 45 patients were randomized (1:1) to our standard dose ATG (total dose of 3.75 mg/kg) (sATG) vs. lower dose of 2.25 mg/kg (lowATG). All patients received tacrolimus and mycophenolate mofetil and underwent early steroid withdrawal within 7 days. The primary end point was biopsy-proven acute rejection at 12 months. Prospective immune phenotyping of freshly isolated PBMCs was performed at baseline, 3, 6 and 12 months after transplantation. The rate of acute rejection was 17% and 10% in the sATG and lowATG, respectively. Analysis of PBMCs revealed equal depletion of CD4 and CD8 effector memory (CD45RO+CD62Llow) T cells at 3 months post-transplant in both ATG arms followed by similar recovery kinetics at 6 and 12 months post-transplant. In contrast, Treg/CD4effmem ratio peaked at 3 months with slightly higher trend in lowATG compared to sATG. No statistically signifi cant differences were found in graft survival, patient survival or infections between the two groups, though there was a trend towards more leukopenia(43% vs. 30%), CMV(8% vs. 0) and BK(4% vs. 0) infections in sATG group vs. lowATG. Recent thymic emigrants T cells (CD4+CD31+CD45RA+) were signifi cantly reduced in both groups post-transplant and had no correlation with the incidence of leukopenia. Lastly, a cost saving of ~US$3,000/patient was seen with lowATG. In sum, in low immunological risk kidney recipients undergoing steroid withdrawal, low dose ATG seems to be safe and effi cacious in preventing acute rejection with potentially lower infectious complications and cost savings. Abstract# C1797 Transition From Dosing Rabbit Antithymocyte Globulin Using Total Body Weight to Adjusted Body Weight Preserves Excellent Outcomes in Obese Renal Transplant Patients. M. Hurrell, W. Ally, C. Eymard, D. Keith, K. Brayman, A. Agarwal. University of Virginia Health System, Charlottesville, VA. Background: The dosing weight utilized to calculate rabbit antithymocyte globulin (ATG) doses for renal transplantation varies according to transplant center and includes ideal body weight, total body weight (TBW) and adjusted body weight (ABW). However, there is limited literature regarding the optimal dosing weight of ATG in obese patients. This study aims to evaluate graft outcomes associated with the use of ABW as compared to TBW in renal transplant patients. Methods: This is a retrospective single center study of adult obese (BMI ≥ 30) solitary renal transplant patients from 2011 to 2013. All patients received either 4.5 mg/kg ATG C1797 Transition From Dosing Rabbit Antithymocyte Globulin Using Total Body Weight to Adjusted Body Weight Preserves Excellent Outcomes in Obese Renal Transplant Patients. M. Hurrell, W. Ally, C. Eymard, D. Keith, K. Brayman, A. Agarwal. University of Virginia Health System, Charlottesville, VA. Background: The dosing weight utilized to calculate rabbit antithymocyte globulin (ATG) doses for renal transplantation varies according to transplant center and includes ideal body weight, total body weight (TBW) and adjusted body weight (ABW). However, there is limited literature regarding the optimal dosing weight of ATG in obese patients. This study aims to evaluate graft outcomes associated with the use of ABW as compared to TBW in renal transplant patients. Methods: This is a retrospective single center study of adult obese (BMI ≥ 30) solitary renal transplant patients from 2011 to 2013. All patients received either 4.5 mg/kg ATG for immediate graft function or 6 mg/kg for delayed graft function (DGF) based on respective dosing weight. One year actuarial patient and graft survival, renal function, and prevalence of rejection were reported. Univariate analysis was performed and p<0.05 was consider signifi cant. Results: 41 obese patients underwent renal transplantation: 28 in the TBW group and 13 in the ABW group. One year patient survival (TBW: 96% vs. ABW: 100; p=ns) and graft survival (96% vs. 100; p=ns) was comparable. Baseline demographics were similar between groups, including BMI (34.1±2.6 vs. 34.1±3.0; p=ns), % patients morbidly obese (BMI >35) (32% vs.38; p=ns), and % patients with DGF (14.3% vs. 38.5; p=ns). The TBW group received more ATG per patient as compared to the ABW group (542±102 mg vs. 430 mg±102, p<0.05) or a 21% reduction in total usage. This represents a decreased cost of $1,388 per patient ($10,789± 3,663 vs. 9,401±2,246; p<0.05). No difference in renal function, as determined by estimated glomerular fi ltration rate, was observed between groups at 3, 6, and 12 months post-transplantation (59±16 ml/min/1.73m2 vs. 57±20; p=ns, 60±19 vs. 56±19; p=ns, 57±22 vs. 51±18; p=ns). Rates of acute rejection were similar between the two groups at 3 and 6 months respectively (21.4% vs. 14.3%; p=ns and 21.4% vs. 15.4%; p=ns). Conclusions: These data suggest that ABW may be safely used to dose ATG while improving value of care through a 21% reduction in ATG usage. Utilizing ABW to dose ATG maintains excellent clinical outcomes with comparable rates of rejection in obese renal transplant patients. Abstract# C1798 Immunoglobulin Induction Therapy in Renal Transplant Recipients Five Year Data of a Prospective Randomized Pilot Study. R. Weimer,1 B. Bartylak,1 A. Staak,1 F. Renner,1 C. Suesal,2 H. Dietrich,1 L. Rainer,1 W. Padberg,3 G. Opelz.2 1Department of Internal Medicine, University of Giessen, Giessen, Germany; 2Institute of Immunology, University of Heidelberg, Heidelberg, Germany; 3Department of Surgery, University of Giessen, Giessen, Germany. Intravenous immunoglobulin (IVIG) administration provides an established treatment modality to reverse steroid resistant rejection and to suppress alloantibody formation in sensitized recipients. To analyze graft protective effects of IVIG induction therapy, we performed a prospective randomized study in 50 renal transplant recipients who were randomly assigned to receive 7x10g IVIG and 7x10g iv albumin infusions, respectively. Immunological tests were performed up to 3 years, and clinical followup data were analyzed up to 5 years posttransplant. IVIG induction therapy did not affect sCD30 and sIL1-RA levels. However, regulatory autoantibody levels were increased in IVIG patients on day 10 (IgG anti-Fab and anti-F(ab)2: p≤0.005; IgA anti-Fab, anti-F(ab)2 and anti-hinge: p<0.05). IVIG patients showed an enhanced monocyte IL-10 production early posttransplant (day 30: p=0.011, unstimulated; p=0.049, LPS), followed by downregulated monocyte activation (p=0.024, 4-month neopterin) and profoundly suppressed 1-year CD4 helper activity compared to non-IVIG patients (p=0.003; logistic regression: p=0.001). However, between IVIG and non-IVIG patients no signifi cant differences were found in 5-year patient and graft survival, graft function, incidence of acute rejections and chronic graft dysfunction. In non-IVIG patients, serum IgG and IgA levels were signifi cantly decreased only within the fi rst 20 days posttransplant compared to IVIG patients (p=0.001, IgG; p=0.039, IgA). The incidence of severe infectious disease, CMV viremia and CMV disease was not signifi cantly different at any time point. Our data show that IVIG induction is associated with potentially graft protective immunological effects: increased regulatory autoantibody levels and upregulated monocyte IL-10 production early posttransplant, followed by downregulation of monocyte activation at 4 months and a profound decrease in CD4 helper activity at 1 year posttransplant. However, no improved clinical outcome (graft outcome; risk of infection) was found up to 5 years posttransplant in this cohort of immunologically low-risk patients. DISCLOSURES: Weimer, R.: Grant/Research Support, Astellas, Novartis. Abstract# C1799 Comparison of Effi cacy and Safety of Different Induction Therapies in Kidney Transplantation From Donation After Cardiac Death. G. Chen, X. Lai, J. Qiu, C. Wang, M. Han, X. He, L. Chen. Organ Transplant Center, The First Affi liated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China. Background Thymoglobulin and ATG-Fresenius (ATG-F) are both commonly used as induction therapy in kidney transplantation from donation after cardiac death (DCD). We carried out a retrospective study to compare the effi cacy and safety between these two induction therapies in DCD kidney transplantation. Method We retrospectively analyzed 255 cases of DCD kidney transplantation performed in our hospital from February 2007 to October 2013. The patients were divided into two groups based on their induction therapies with thymoglobulin (n=188) or ATG-Fresenius (n=67). All patients were followed up for at least 3 months. The primary endpoints included delayed graft function (DGF), acute rejection, graft loss and patient death. Postoperative complications were also compared between two groups, including infection, leucopenia, thrombocytopenia, and tumors. Results DGF occurred in 36(19.1%) patients in thymoglobulin group versus 17(25.4%) patients in ATG-F group (p=0.281). However, if we selected the patients with increased risk factors for DGF (includi