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Kidney Week

Abstract: PO2086

A Successful Approach for A2 to B Cadaveric Renal Transplantation

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical


  • Sogbein, Olusola, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
  • Kumar, Anand, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
  • Mujtaba, Muhammad Ahmad, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States

Approximately 20% of blood group A individuals have reduced levels of A-antigen, termed A2, with less immunogenicity toward anti-A1 immunoglobulins. This allows the safe transplant of A2 kidneys into B or AB recipients. In 2014, the Kidney Allocation System was modified to encourage transplant centers to provide A2 kidneys for type B patients to reduce inequities in access. Studies have reported that rates of A2 to B transplants remain underutilized due to high rates of early acute rejection or thrombotic microangiopathy (TMA). We report on outcome metrics of A2 to B transplantation at the University of Texas Medical Branch (UTMB).


A retrospective, single center analysis of 29 patients who received A2 to B kidney transplants at UTMB between July 2015 and December 2020. We included stable (2 consecutive) anti-A IgG titers ≤ 1:8 for A2 identified individuals. Anti-A titers were monitored quarterly in B waitlisted patients. All A2/A2B to B eligible recipients underwent pre-transplant volume exchange plasmapheresis, followed by 2 additional sessions on post-op days 1 and 3. Thymoglobulin was used for induction and steroids for maintenance immunosuppression.


A major concern in A2 to B transplant is the development of TMA or graft rejection. The incidence of rejection within the first year of all types of renal transplants ranges from 7.9% to 21.4%. We instituted an aggressive plasmapheresis protocol to reduce levels of potential pre-formed IgM anti-A antibodies that may induce graft failure. We report a rate of 3.4% for rejection or TMA within the first year of graft life which is less than previously published reports. This is due to pre- and post-transplant plasmapheresis in combination with intravenous immunoglobulin therapy. We elected not to follow anti-A titer levels post-transplant which did not result in higher rates of graft loss.


Our A2 to B transplant patients had a low rate of rejection and TMA demonstrating the efficacy of our triple maintenance immunosuppression protocol. Anti-A titers need not be followed post-operatively.

Cellular or Antibody mediated rejection at 1 year (%)3.45
Thrombotic Microangiopathy at 1 year (%)3.45
Kidney Allograft Survival at 1 year (%)96.55
Patient Survival at 1 year (%)100.00

Table 1