Mastering the risk of HLA antibodies in kidney transplantation: an algorithm based on pretransplant single-antigen flow bead techniques.
The utilization of sensitive techniques of detection of HLA antibodies to define and measure sensitization has greatly evolved in recent years. We present here an approach to minimize the risk of HLA antibodies in kidney transplantation based on the evaluation of graft accessibility of sensitized patients by calculated PRA (cPRA) and estimation of potential matched donors (PMD) using a national simulation software program. This study included all registered patients on our waiting list (WL) for deceased donor (DD) kidney transplants. All patients were screened by single-antigen flowbead (SAFB) techniques. Of the 502 registered patients, 174 (34.7%) were sensitized. Among these, 48.3% (84 pts) had a cPRA>85%. For 75.3% of sensitized patients (90 pts with cPRA≤85% and 41 pts with cPRA>85%), the flow of PMD was considered sufficient to allow a transplant avoiding all unacceptable antigens. The 41 patients with a cPRA>85% (48.8%) had a satisfactory donor flow in the framework of the national prioritization program for highly sensitized patients. Finally, 43 sensitized patients (24.7%) were deemed eligible for a strategy of higher immunological risk through desensitization protocols or transplantation against HLA-DSAs. This approach provides a logical and systematic strategy to rationalize the access of sensitized patients to kidney transplantation minimizing the risk of HLA antibodies.
JASN - PMID: 20634297
The clinical importance of preexisting HLA antibodies at the time of transplantation, identified by contemporary techniques, is not well understood. We conducted an observational study analyzing the association between preexisting donor-specific HLA antibodies (HLA-DSA) and incidence of acute antibody-mediated rejection (AMR) and survival of patients and grafts among 402 consecutive deceased-donor kidney transplant recipients. We detected HLA-DSA using Luminex single-antigen assays on the peak reactive and current sera. All patients had a negative lymphocytotoxic cross-match test on the day of transplantation. We found that 8-year graft survival was significantly worse (61%) among patients with preexisting HLA-DSA compared with both sensitized patients without HLA-DSA (93%) and nonsensitized patients (84%). Peak HLA-DSA Luminex mean fluorescence intensity (MFI) predicted AMR better than current HLA-DSA MFI (P = 0.028). As MFI of the highest ranked HLA-DSA detected on peak serum increased, graft survival decreased and the relative risk for AMR increased: Patients with MFI >6000 had >100-fold higher risk for AMR than patients with MFI <465 (relative risk 113; 95% confidence interval 31 to 414). The presence of HLA-DSA did not associate with patient survival. In conclusion, the risk for both AMR and graft loss directly correlates with peak HLA-DSA strength. Quantification of HLA antibodies allows stratification of immunologic risk, which should help guide selection of acceptable grafts for sensitized patients.
Comparison of combination Plasmapheresis/IVIg/anti-CD20 versus high-dose IVIg in the treatment of antibody-mediated rejection.
American Journal of Transplantation - PMID: 19422335
Different strategies appear to improve the success in treatment of antibody-mediated rejection (AMR), although no one best method has yet emerged. The objective of this study was to compare the efficacy of the combination of Plasmapheresis/intravenous immunoglobulin (IVIg)/anti-CD20-based regimes versus high-dose IVIg alone in the treatment of AMR. Group A (12 patients) was treated with high-dose IVIg between January 2000 and December 2003; group B (12 patients) was treated by Plasmapheresis/IVIg/anti-CD20 between January 2004 and December 2005. Graft survival at 36 months was 91.7% in group B versus 50% in group A (p = 0.02). Donor-specific human leukocyte antigens (DSA) levels detected by Luminex single antigen (Luminex SA) and ELISA, 3 months postrejection are significantly lower in group B than in group A: DSA ELISA class 2 score 6-8 (p = 0.02), DSA mean intensity of fluorescence (MFI) max (p = 0.009) and DSA mean MFI (p = 0.0004). The persistence of elevated DSA levels posttreatment is more frequent in patients with graft loss as compared to those with preserved renal function: score 6-8 on ELISA (p = 0.04); mean MFI (p = 0.00009) and MFImax (p = 0.018). We conclude that: (1) high dose IVIg alone is inferior to Plasmapheresis/IVIg/anti-CD20 as therapy for AMR and (2)DSA postrejection can be quantified using solid phase assays, showing that 3 months after AMR, DSA levels are higher in patients with graft loss.
Paris Transplant Group
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