13Strategies used to avoid/minimize transplant rejection HLA typing and matching of recipient/donor pairsDetection of donor specific HLA antibodies.Lymphocyte crossmatchComplement dependent cytotoxicity (CDC) crossmatch.Flow cytometry crossmatch (newer technique, much more sensitive)Virtual crossmatchIdentification of HLA antibodies in recipient serum by solid phase assayHLA typing of the donor (and recipient)Correlation of recipient HLA antibodies and donor/recipient typing
14HLA antibody identification by Luminex (solid phase) AssayHLA antigen coated microspheresTells the instrumentwhich bead is being examined2 lasersTells the instrument how much antibody is bound to the bead
15HLA antibody detection by Luminex assay 12345678910
16HLA antibody detection by Luminex assay 12345678910A1A2A3A11A23A24A25A26A29A30
17HLA antibody detection by Luminex assay 897A26A29A254106810A119A3015A24A26A301A29A1A232A15A236A237A3A24342A25A3A11A2
18HLA antibody detection by Luminex assay 897A26A29A254106810A119A3015A24A26A301A29A1A232A15A236A237A3A24342A25A3A11A2
19HLA antibody detection by Luminex assay 897A26A29A254106810A119A3015A24A26A301A29A1A232A15A236A237A3A24342A25A3A11A2
20HLA antibody detection by Luminex assay 897A26A29A254106810A119A3015A24A26A301A29A1A232A15A236A237A3A24342A25A3A11A2
21HLA antibody detection by Luminex assay PE-a-IgG897A26A29A254106810A119A3015A24A26A301A29A1A232A15A236A237A3A24342A25A3A11A2
22HLA antibody detection by Luminex assay 897A26A29A254106810A119A3015A24A26A301A29A1A232A15A236A237A3A24342A25A3A11A2
24HLA Class I antibody analysis Patient A3,31 B7,60 DR1,14 (52) DQB5,6
25HLA Class I antibody analysis Patient A3,31 B7,60 DR1,14 (52) DQB5,6Donor A1, B DR7,17 (53,52) DQB2
26HLA Class I antibody analysis Patient A3,31 B7,60 DR1,14 (52) DQB5,6Donor A1, B DR7,17 (53,52) DQB2Unacceptable antigens: A1, A36, B8
27HLA Class II antibody analysis Patient A3,31 B7,60 DR1,14 (52) DQB5,6Donor A1, B DR7,17 (53,52) DQB2
28HLA Class II antibody analysis Patient A3,31 B7,60 DR1,14 (52) DQB5,6Donor A1, B DR7,17 (53,52) DQB2Unacceptable antigens: DR7, DR53, DQ2
29What is the clinical relevance of donor specific HLA antibodies detected pre-transplant by solid phase assay?
30Amico et al. Transplantation 2009 Significant increase in biopsy proven AMR in patients with pre-transplant DSA
31Lefaucheur et al. JASN 2010Significant decrease in graft survival in patients with pre-transplant DSAClass I and Class II DSA confer similar risk.
32What about PRA? (probability of a positive crossmatch)
33Calculated PRAcalculated PRA (cPRA) is based on the unacceptable HLA antigens listed for a patientcPRA is determined using an established algorithm (Zachary et al) and HLA frequencies derived from the HLA phenotypes of more than 12,000 donors recently entered into the US OPTN registry
34CPRA Calculator http://optn.transplant.hrsa.gov/ Resources, professional resources, choose cPRA calculator from options
36Tambur et al. AJT 2009Correlation between virtual and Flow crossmatchFP 3.1%Non-HLA absFalse pos FCXMFN 14%Some allele specific non-DSASome weak DSA
37Tambur et al. AJT 2009Virtual crossmatch is a good tool to predict HLA compatibility.Caveats:Antibodies against all donor HLA antigens have to be investigated.Strength of the antibody has to be considered.Non-HLA antibodies.
38A Virtual Crossmatch Protocol Significantly Increases Access of Highly Sensitized Patients to Deceased Donor Kidney Transplantation.Bingaman et al. Transplantation 2008FP = 3%12%Cost effectiveDecreased TATIncreases access to transplantation of highly sensitized patients
39Negative virtual crossmatch predicts negative flow crossmatch Crossmatches performed since implementationof flow crossmatch (June 2010 – September 2011).157FP rate = 2.5%4
41Renal Transplant Patient Workup HLA typing, SSO.Sera collected monthly and after sensitizing event.Antibody identification by Luminex every 3 months.Unacceptable antigens and HLA typing are entered into MOTP database.Donor HLA typing performed and entered into MOTP database.Smartmatch excludes potential recipients with unacceptable mismatches.Top 5 potential recipients are selected for crossmatch.Top 2 recipients with negative crossmatch proceed to TxDay of transplant serum and sera collected at 3 weeks and 3 months post transplant are also tested.
58Living Donor Paired Exchange National Program for incompatible recipient/donor pairs (living kidney donation)Pairs incompatibility due to:Presence of donor specific HLA antibodiesABO blood group incompatibilityRecipient/donor pair information is entered into databaseHLA typing, HLA antibodies, blood group, clinical parameters.Computer program matches incompatible pairs with others using a virtual crossmatch principle.Major impact on rate of kidney transplantation.
59Living Donor Paired Exchange Group AHLA-A1,3Donor 2Group OHLA-A2,3XXRecipient 1Group BNo HLA absRecipient 2Group AAnti-HLA-A22 way exchange
60Living Donor Paired Exchange Donor NRecipient 1Recipient 2Recipient 3Recipient NN way exchange
61Conclusions Major improvement in HLA testing over the last few years Implementation of state of the art technology and methodologyAllows more complete assessment of immunologic riskBetter clinical outcomesDecreased TAT/Decreased costIncreased rate of transplantation through participation in LDPE program