With the longest wait times and lowest rate of transplantation, ABO type B renal transplant candidates are at a disadvantage when compared to their type O, A, and AB counterparts. The transplant community has long attempted to ameliorate this discrepancy, and in 2014 the national Kidney Allocation System (KAS) officially recognized A2 and A2B donors as compatible contributors for a subset of ABO type B candidates with low anti-A IgG titers. Anti-A IgG titers have been regarded as integral to long term graft survival and studies have shown that titers of < 1:8 yield excellent outcomes in A2 to B renal transplantation. Additionally, with appropriately low levels of anti-A titers, there have been exceptional results reported without the need to initiate desensitization or significantly deviate from standard immunosuppression protocols in A2 to B recipients. Despite the changes made to enhance donor allocation to ABO type B recipients, the rate of A2 to B ABO incompatible renal transplantation has yet to reach its full potential.

Due to a longstanding regional variance, our center has a 20-year experience with A2 to B renal transplantation. With that data and the long-term follow-up it affords us, the aim of this study is to illustrate both clinical and immunologic outcomes of 10 ABO incompatible (A2 to B) renal transplant recipients with associated anti-A titer data. The outcomes were compared to a matched subset of 10 ABO compatible renal transplant recipients (B to B). Graft and patient survival were found to be equivalent, as were secondary endpoints, which included; DSA, rates of DGF, rejection episodes and types of immunosuppression regimens. Of equal significance, ABO incompatible renal transplant recipients were found to have little to no change in anti-A titers in the first two weeks post-operatively. There was a single patient with elevated titers post-operatively (1:16), however this failed to correlate clinically with no rejection episodes to date. None of the patients in the study received desensitization or deviated from our standard immunosuppression regimen, with follow-up between 1-6 years. This limited study exposes the hidden repository of donor allografts for one of our most vulnerable patient populations without additional patient burden or over-utilization of healthcare resources.

CITATION INFORMATION: Barnhill C., Warner P., Weiss A., Kuhr C., Cowan N., Brandenberger J. Equivalent Clinical Outcomes and Stable Post-Operative Anti-A IgG Titers in A2 to B Renal Transplant Recipients Compared to Matched B to B Cohort Am J Transplant. 2017;17 (suppl 3).

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