Predictive Value of the Strength and Class of Pre Transplant Donor Specific Antibodies (DSA) On Clinical Outcomes in Renal Allograft Recipients.

Abstract

Background: The strength of pre-transplant donor-specific HLA antibodies (DSA) has been questioned as a quantifiable tool in the prediction of future immunologic injury. Desensitization is often considered based upon DSA MFI in the setting of a negative flow cytometry crossmatch (FCXM). The type of DSA has also been purported to be predictive of post-transplant outcomes. However, attempts to identify pre-transplant DSA characteristics that correlate with graft outcomes have yielded inconsistent results.[/bold] Methods: 547 consecutive recipients of a first kidney or kidney/pancreas transplant with a negative pre-transplant FCXM between September 2007 and August 2012 at our center were included in the analysis. All patients underwent cell-based FCXM and SAB analysis (LABScreen beads, One Lambda Inc.) on current and historic sera prior to transplantation. Results: Of 547 patients with a negative FCXM included in the analysis, 196 had DSA (DSA+, MFI ≥500) detected at any point prior to transplant by SAB analysis. One year acute rejection (AR) and three year graft survival were similar in DSA+ vs. DSA- patients. AR was more likely in patients with DSA MFI ≥1000 at any time prior to transplant (20% vs. 9% and 11% for MFI < 1000 and DSA-, p=0.039), but did not correlate with DSA class. With a median follow-up period of 2.3 years, graft function and proteinuria were similar in all groups irrespective of DSA strength or class. Three year graft survival was similar with DSA strength ≥ 1000 MFI, ≥ 3000 MFI (p=0.74), and with respect to class.Figure: No Caption available.Conclusion: Pre-transplant DSA with a negative FCXM is not associated with poor graft outcomes, and further characterization of DSA by strength and class does not reveal a correlation with long term graft survival. While pre-transplant DSA MFI ≥ 1000 warrants careful monitoring for AR, neither antibody strength nor class should represent a barrier to transplant in the setting of negative FCXM.