P052 In search of a gold standard for a low immune risk kidney transplant. Flow cytometry crossmatch or single antigen beads?

Abstract

Aim After several years of the introduction of the single antigen bead assay (SAB), no consensus have been reached about the most reliable way to interpret its positive results and many different protocols have been tested (denatured beads, EDTA, heat, dilutions, C1q and others). The absence of reaction, leading to a negative virtual crossmatch, is probably the only result widely accepted. It is the policy of our hospital to offer a kidney graft to every patient on the waiting list, even in the presence of anti-HLA antibodies against the donor (DSA) by the SAB, provided that the flow crossmatch is negative. The aim of this study is to analyze the outcome of these transplants and validate, or not, this liberal policy. Methods All deceased kidney donor transplants (N = 526) performed between March 2013 and March 2016 were included. All had a negative pre-transplant T and B cell flow crossmatch. The presence of anti-HLA antibodies was done by single antigen beads (OneLambda) using the Luminex platform after heat treatment of the sera. Anti HLA-DP antibodies were excluded from this study because of lack of HLA-DP typing of the donors. Results We evaluated the following parameters: graft survival, patient survival, creatinine at 1 year and donor age. These parameters were compared with the presence or absence of DSAs anti-A, B, C, DR and/or DQ, and also with the sum of the mean fluorescence index (MFI) of the combined DSAs. None of the parameters included showed any statistical difference. One year patient survival was 92.7 × 90.2% ( p= 0.723) comparing presence or absence of DSAs. One year graft survival was 83.6 and 85.7% (including loss by death) with and without pre-transplant DSAs (p = 0.689). The 1 year mean creatinine was 1.85 and 1.77 with and without DSAs (p = 0.318) and the donor age (>60 or Conclusions Our results showed no difference in patient, graft survival and the 1 year creatinine in recipients transplanted with or without DSAs, provided that the pre-transplant flow crossmatch was negative. We believe that our liberal policy of offering a kidney to patients in spite of DSAs is justified, at least in this small series and in this short follow up.