Monday, September 27, 2010 2:00 PM - American Society for ...

7-ORTHE IMPACT OF A POSITIVE ENDOTHELIAL CELL CROSSMATCH (ECXM) IN ANINCOMPATIBLE RENAL TRANSPLANT RECIPIENT.Annette M. Jackson 1 , Robert A. Montgomery 2 , Lorraine C. Racusen 3 , Edward S. Kraus 1 . 1 Medicine, JohnsHopkins University, Baltimore, MD, USA; 2 Surgery, Johns Hopkins University, Baltimore, MD, USA;3 Pathology, Johns Hopkins University, Baltimore, MD, USA.Aim: To investigate the impact of non-HLA antibodies following an ABO and HLA incompatibletransplant (tx).Methods: Flow cytometric crossmatches were performed using donor lymphocytes (FCXM) andendothelial cell precursor cells (ECXM) as targets. ECs were isolated using magnetic beads coated withanti-Tie2 antibodies. Donor specific HLA antibodies (DSA) were detected using solid phaseimmunoassays. Allograft rejection was defined using Banff criteria.Results: A 60 year old male with a cPRA of 55% received a kidney tx via paired kidney donation. Thedonor was ABO incompatible (blood group B to O) but provided a reduced HLA barrier (FCXM+) whencompared to his original donor (CDC+, titer 32). Positive T and B cell FCXMs were consistent with DSAto HLA-A11 and A31.The patient was desensitized using plasmapheresis (PP), low dose IVIg, anti-CD25,and anti-CD20 antibodies. The patient’s anti-B titer fell from 256 to 8 and FCXMs were negative by day oftx. The patient was discharged with a serum creatinine (SCr) of 1.3 mg/dl and an anti-B titer of 4. A biopsy,24 days post-tx, showed 2A cellular rejection with a component of AMR with no rise in DSA or anti-Btiter. Following treatment with a T cell depleting antibody and PP, his SCr returned to baseline. Biopsiesperformed at 3 and 4 months post-tx showed persistent AMR with no significant change in DSA or ABOantibodies; the patient was treated with high dose IVIg. ECXM tests were performed and showed a positiveECXM pre-tx in the presence of HLA-A11 and A31 DSA, a negative post-tx ECXM followingdesensitization, and positive ECXMs at 4 and 7 month post-tx (pre and post high dose IVIg treatment).Conclusions: Non-HLA antibodies were detected concomitant with AMR in a patient following anincompatible tx. These antibodies were reduced following PP and low dose IVIg treatments but weobserved no reduction following treatment with high dose IVIg.8-ORARE HLA Cw DONOR SPECIFIC ANTIBODIES AS CLINICALLY SIGNIFICANT IN AMR INRENAL TRANSPLANTATION AS ARE OTHER HLA ANTIBODIES? A CASE STUDY.Luz Stamm 1 , Mauricio Monroy-Cuadros 2 , Kevin McLaughlin 2 , Noureddine Berka 1 . 1 Tissue Typing,Calgary Laboratory Services, Calgary, AB, Canada; 2 Southern Alberta Transplant Program, AlbertaHealth Services, Calgary, AB, Canada.Aim: A 35 year old female with Goodpasture’s disease was worked up for an unrelated living donorkidney.[table1]The AHG-CDC crossmatch was negative, Flow T cell crossmatch was positive. SingleAntigen (SA) by Luminex showed antibodies with specificity to Cw antigens with the strongest bead (MFI5000) directed to donor specific antibody (DSA) Cw9 (3).[table2]Methods: Patient received 360 mg of Mycophenolate Acid a week prior to the transplant and was inducedwith 75mg of ATG. A triple therapy immunosuppression was started with FK-506, Mychophenolate acidand steroids.Results: Creatinine level came down and reached her baseline of 85 µmol/L after the first week. The titerand specificity of DSA is being monitored closely in this patient and up to date DSA remain the same asinitially tested.Conclusions: Little information can be found in the literature as to the implication and relevance of HLACw donor specific antibodies in the risk of acute antibody mediated rejection in renal transplantation. Inthis unique case, this patient’s antibodies are specific to HLA Cw making it an interesting case for followup. Since the cell surface expression of the C locus antigens has been estimated at 10% in relation to A andB antigen, its relevancy in the importance of rejection is not known. Studies have been focusing on theimportance of the HLA epitopes sites to which the antibodies bind. With the development of SAtechnology, the identification of these epitopes has proven very useful. This case may help to prove theclinical importance in the future analysis of HLA Cw antibodies.