60-P

Abstract

HLA Ab or DSA pre/post transplantation (Tx) has been associated with poor renal graft outcomes. It is unclear which HLA sensitized patient will or will not experience rejection or graft loss. The purpose of our study was to identify recipients (recips) at greatest risk for post Tx rejection and/or graft loss. We evaluated 277 renal-Tx recips that had sufficient pre/post HLA Ab data. Antibody mediated rejections (AMR) were biopsy confirmed and treated with Thymoglobin, Pheresis and Rituxin while cellular rejections were treated with steroids. All donor-recips were ABO compatible and transplanted following a negative donor-specific FCXM using historical and pre-Tx recip sera. Recips were risk-ranked according to whether they had or did not have HLA and/or DSA post-Tx. A subgroup of patients with persistent HLA or DSA Ab (presenting at least two or more times) was identified. HLA Ab and/or DSA were identified using SAB (One Lambda, Inc.) and a Luminex based solid phase assay platform. Mean Fluorescence Intensity (MFI) of 1,000 was considered positive. Of 277 renal Tx recips, 92 presented with no HLA or DSA post-Tx while 185 recips had positive Ab post-Tx. Of the 185 recips with Ab post-Tx, 31% (58/185) presented with DSA. The frequency of AMR for no Ab vs positive Ab post-Tx was significantly different 8% (7/92) vs 21% (39/185), p < 0.01 as was the three year graft survival of 92% (82/92) vs 87% (164/185), p < 0.02 for the same patients. There were 58 patients with positive post-Tx Ab that were DSA positive, however, only 67% (39/58) of these displayed persistent Ab and only 54% (21/39) of these lost their grafts. Moreover, 50 recips that presented with a pre-Tx positive DSA would not have been considered for a donor crossmatch using the virtual crossmatch. These data suggest that not all post-Tx Abs that are DSA positive result in AMR or graft loss. Recips with persistent DSA appear to be at a higher immunological risk for AMR and/or graft loss.