S. G. Lattimore1, N. J. Skill1, M. A. Maluccio1 1Indiana University School Of Medicine,Transplant,Indianapolis, IN, USA
Introduction: Rabbit thymoglobulin is an anti-thymocyte globulin (rATG) used in transplant to eliminate lymphocytes. However, anti-rATG antibodies are associated with both acute and chronic rejection. The purpose of this study is three-fold. Firstly, to report the incidence of anti-rATG in a large renal transplant center. Secondly, to evaluate outcomes, risk factors, hazard ratios, and costs associated with positive ATG antibody titer. Finally, investigate CD40L and IL21, both linked to antibody mediated rejection, as alternate targets for patients with anti-ATG antibodies.
Methods: Clinical records were reviewed of renal transplant recipients between January 2004 and May 2018 for anti ATG antibody titers. Serum CD40L and IL21 quantifications were performed using commercially available ELISA. Cost analysis was extracted from billing records 0-7 days post rATG titer using total charges as a proxy for cost.
Results: Between 2004 and May 2018 the Indiana University Hospital transplant program performed, on average, 160 renal transplants per year. Anti rATG antibody ELISAs was requested and performed for 19 patients per year (11.8%), 4.8 patients per year were positive at 1:100 titer (25.3%). anti rATG antibodies was associated with a significantly lower time to rejection (137days) when compared to negative patients (873 days). No correlation between rATG antibodies and time of dialysis, or lymphocytes populations was found. A slight correlation was observed between positive rATG antibody titer and recipient age. Anti rATG rates were greater in patients receiving a second kidney (37.5%). Cost of treatment in patients with positive anti-ATG titer was significantly lower ($39,549±9,504 vs 117,503±16,273 ttest p=0.0001). IL21 and CD40L were significantly greater in patients with positive anti-ATG antibody titer when compared to patients whom were negative.
Conclusion: Anti rATG antibodies significantly impact outcomes and costs of kidney rejection. Monitoring of anti rATG antibody titer is required to evaluate outcomes and treatment options, especially in the setting of second transplants. Elucidation of the mechanisms associated with positive anti rATG antibody is required. IL21 and CD40L are potential targets.
