Donor-specific anti-HLA antibodies (DSA) cause acute and chronic antibody-mediated rejection (AMR) and significantly compromise allograft survival. Clinical relevance of antiHLA-Cw antibodies is still unclear with conflicting reports about their pathogenicity. Their role, in the absence of any other anti-class I and II antibodies, remains unknown. We evaluated the clinical relevance of the presence of DSA anti-Cw present at day 0 (D0) in renal transplant recipients (RTR).

Methods: 19 RTR with isolated anti-Cw DSA (measured by Luminex) at D0 prior to transplantation were followed during one year. Immunosuppressive treatment included steroids, mycophenolatemofetil, calcineurin inhibitors, and induction therapy with basiliximab (n=6) or antithymocyte globulin (n=12). To prevent AMR, some patients received plasma exchanges (PE, n=7), anti-CD20 (n=5) and intravenous immunoglobulins (IVIg, n=15). AMR was classified according to Banff classification.

Results: Although one year graft and patient survival were respectively 94,7% and 100%, AMR were diagnosed in five patients (26,3%). Mean level of DSA at D0 was 7622,2 [978-17941] Mean Fluorescent Intensity (MFI) for those patients and 2927,4 [522-8012] MFI for those without AMR. AMR were treated with methylprednisolone, PE, IVIg and anti-CD20. At one year post-transplant, GFR was respectively 48 mL/min/1.73m² in the AMR group and 53,8 mL/min/1,73 m² in controls. The one-year biopsy showed persistant glomerulitis (grade1 and 2) and peritubular capillaritis (grade 1 to 3) in all but one patient.

Conclusion: Patients with high level of pretransplant donor-specific HLA-Cw antibodies are likely to develop acute AMR. Their presence must therefore be taken into account to choose immunosuppressive regimen.

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