Date: Saturday, May 30, 2020
Session Name: Poster Session A: Histocompatibility and Immunogenetics
Session Time: 3:15pm-4:00pm
Presentation Time: 3:30pm-4:00pm
*Purpose: Donor specific HLA antibodies (DSA) that develop in the face of donor-recipient HLA mismatches are well-established independent predictors of graft loss in solid organ transplantation. We previously reported that pediatric patients whose donors were mismatched for a single epitope – a proline residue at position 55 that resides within all three HLA-DQ3 antigens (DQB1*07,*08,*09) – were at greater risk to develop de novo DSA compared to other donor HLA mismatches. Here, we aimed to determine underlying donor-recipient characteristics in our pediatric renal transplant cohort to explain the prevalence of DQ3 DSA post-transplant.
*Methods: We retrospectively studied 131 pediatric renal transplant recipients, including 48 African Americans (AA) and 55 Caucasian (Cs) recipients, transplanted between 2012 and 2016. We documented the development of DSA and the prevalence of DQ3 antigens among recipients and donors. We also compared the frequencies of DQ3 antigens in Cs and AA.
*Results: In total, 42 (32%) patients developed de novo DSA; of those 12 (29%) were DQ3 antibodies, which included 8 AA and 3 Cs recipients (and 1 non-AA, non-Cs). Cs were significantly more likely to express DQ3 antigens compared to AA (p=0.0014) when recipients and donors were assessed together. Among recipients, 17/48 (35%) AA expressed DQ3 antigen while 30/55 (55%) Cs expressed DQ3 antigen (p=0.052). Among donors, 12/32 (38%) AA expressed DQ3 antigen compared to 51/83 (61%) Cs (p=0.021). Finally, 50% (19/38) of the DQ3 mismatches were seen in AA recipients compared to 34% (13/38) in Cs (p=0.081).
*Conclusions: We observed that approximately one third of the de novo DSA that developed in our pediatric renal transplant population were to DQ3 antigens. Importantly, AA expressed DQ3 antigens significantly less than Cs, an unanticipated observation that, to our knowledge, has not been previously reported. Thus, when an AA recipient is paired with a Cs donor, there will be a higher probability of DQ3 antigen mismatches and the development of de novo DQ3 DSA. These data warrant further investigation to determine the long term allograft outcome among such mismatched pairs, especially AA recipients who, as shown here, are statistically less likely to express DQ3 antigens than their likely Cs donors.
To cite this abstract in AMA style:Gattis S, George R, Liverman R, Serluco A, Garro R, Figueroa J, Bray RA, Gebel HM, Sullivan HC. Anticipated Observations: The Role of DQ Antigen Frequencies among Donors and Recipients in a Pediatric Renal Transplant Cohort [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/anticipated-observations-the-role-of-dq-antigen-frequencies-among-donors-and-recipients-in-a-pediatric-renal-transplant-cohort/. Accessed November 30, 2020.
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