THE BRAZILIAN ACCEPTABLE MISMATCH PROGRAM PROPOSAL TO ENHANCE TRANSPLANTATION FOR HIGHLY SENSITIZED PATIENTS

摘要

A program based on acceptable HLA mismatches (AM) has shown to be an efficient tool to increase the transplantability of highly sensitized patients (HSP) in Eurotransplant (1). The purpose of this report is to describe the Brazilian experience using a similar approach. For the definition of HLA-A, B AM for 40 HSP (Class I PRA >=80%, LabScreen~R PRA, One Lambda Inc), we combined information from the HLAMatchmaker analysis (ABC Eplet Antibody Analysis Version 1.3) (2, 3) and results of the serum screening with Single Antigen (SA) assay (One Lambda). The cutoff of the SA was determined for each serum, using the following algorithm: (1) reactions with nMFI (normalized median fluorescence intensity) values>=500 corresponding to different alleles of the same specificity were taken as surrogates of positive reactions and the cut-off value was tentatively set immediately below the allele with the lowest nMFI; (2) reactions with nMFI < 500 ("truly negatives") were inserted into the HLAMatchmaker program, along with patient's HLA-A, B phenotype; (c) if no more than five AM defined by the Matchmaker presented MFIs above the tentative cut-off, this cut-off was validated; otherwise, the cut-off was set at 500 nMFI.