Session Name: Poster Session C: Kidney Deceased Donor Allocation
Session Type: Poster Session
Date: Saturday, May 30, 2020
Session Time: 3:15pm-4:00pm
Presentation Time: 3:30pm-4:00pm
*Purpose: Decreased antigen expression among blood group A subtype 2 (A2) donor kidneys allows these organs to be considered as universal donors; under the new Kidney Allocation System, they are preferentially transplanted into blood group B recipients with low anti-A titers. Blood group B and O recipients with low titer pre-transplant anti-A have had excellent outcomes after A2-incompatible transplantation. However, post-transplant acute antibody-mediated rejection (AbMR) still occurs, and anti-A titer rebound is common. To date, no study has examined the correlation between this rebound and likelihood of AbMR.
*Methods: We report 22 ABO-incompatible A2/A2B to B/O transplants at a single center with pre-transplant anti-A gel titers ≤64 who underwent prospective post-transplant titer monitoring. Immunosuppression consisted of anti-thymocyte globulin induction, tacrolimus, mycophenolate mofetil and prednisone. No patients received pre-transplant conditioning regimen with therapeutic plasma exchange (TPE). Anti-A titers were measured at baseline and daily for 14 days post-operatively. Biopsy was performed if anti-A titers rebounded above pre-transplant levels.
*Results: Recipients were predominantly blood type B (B:59%; O:41%), male (64%), black (55%), and received deceased donor kidneys (55%). Median pre-transplant gel titers were ≤64 (range 2-64) and declined in all patients immediately after transplantation. Median time to onset of rebound was 5 days (range 4-6). Median time to peak rebound was 10 days (range 9-12 days). Three/22 (13%) patients had biopsy-proven Banff AbMR (>1: thrombotic microangiopathy, glomerulities and peritubular capillaritis), no graft dysfunction at the time of rise in titer, but mild graft dysfunction at biopsy. Baseline pre-transplant titers did not correlate with AbMR but post-transplant titers did (Figs. 1&2). Three patients with AbMR were treated with TPE, low-dose IVIg, and anti-C5 antibody with excellent clinical response; follow up allograft biopsy at 3 months showed complete morphologic resolution and no allografts were lost to AbMR.
*Conclusions: Pre-transplant anti A titers do not tell the full story regarding AbMR. Until further pathophysiology of the AbMR is defined, it is essential to continue monitoring anti A titers immediately following transplant as it appears to herald AbMR. Furthe more with prompt and aggressive treatment, AbMR in this setting appears to resolve completely .
To cite this abstract in AMA style:Kumar V, Mompoint-Williams D, Marques M, MacLennan P, Mustian M, Locke J. Post-Transplant Rebound and Not Baseline Anti-A Titers are Associated with Acute Antibody-Mediated Rejection in A2– to B/O Incompatible Kidney Transplantation [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/post-transplant-rebound-and-not-baseline-anti-a-titers-are-associated-with-acute-antibody-mediated-rejection-in-a2-to-b-o-incompatible-kidney-transplantation/. Accessed December 3, 2023.
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