Background: The new kidney allocation system implemented in December 2014 allowed for use of A2/A2B donors to B recipients. However there is no mandate by UNOS and each center should decide what anti-A2 titers to accept and also what immunosuppressive protocol to use. We aimed to investigate the clinical outcomes of A2-incompatible kidney transplant recipients at our center after the new allocation system was implemented.

Methods: Between 3/2015 and 9/2016, we performed 21 A2-incompatible kidney transplants at our institution. A2-incompatible transplantation is performed if pretransplant anti-A2 titers are equal or less than 1/16 and all patients should receive anti-thymocyte globulin induction.

Results: Of the 21 recipients who received A2-incompatible transplant, 90% of the recipients were male, 47% African-American, with a mean age of 55 ± 18.8 years. There were 20 deceased donor renal transplants and one living related. Mean class I PRA at the time of the transplant was 4.8±17.8 % and class II was 18.5±31.4 %. Four patients had pretransplant donor-specific-antibodies. Pretransplant anti-A2 titers were 1/2 in 13 patients, 1/4 in 2, 1/8 in 3, and 1/16 in 3 recipients. Maintenance immunosuppression consisted of tacrolimus, mycophenolate and prednisone in all patients. During a median follow-up of 6 months (2-20), patient survival was 91% (2 patients died due to cardiovascular disease and sepsis). Death censored graft survival was 100%. There were no episodes of acute rejection. Four patients underwent a clinically indicated kidney biopsy. All the biopsies showed ATN without any acute rejection findings but C4d positivity without other evidence of rejection was seen in 3 patients. The median serum creatinine level at last follow up was 1.4 mg/dl (0.9-4.3). Only one patient developed BKV viremia (4.7%). None had developed CMV viremia or malignancy.

Conclusion: A2-incompatible transplantation appears to be safe in patients with anti-A2 titers less than 1/16 with good short-term kidney allograft outcomes. C4d positivity is frequent in allograft biopsies without acute rejection.

CITATION INFORMATION: Kamal L, Ajaimy M, Lubetzky M, DeBoccardo G, Bedi P, Greenstein S, Rocca J, Graham J, Kinkhabwala M, Chokechanachaisakul A, Courson A, Akalin E. A2 Incompatible Kidney Transplantation: A Single Center Experience. Am J Transplant. 2017;17 (suppl 3).

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