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Renal Transplantation |












* Renal Division,
Recanati/Miller Transplantation Institute, Mount Sinai School of Medicine,
Immunogenetics Laboratory, Rogosin Institute, and
Renal Division and Transplant Services, North Shore University Hospital, New York, New York
Correspondence: Dr. Enver Akalin, Mount Sinai Medical Center, One Gustave L. Levy Place, Box 1104, New York, NY 10029-6574. Phone: 212-659-8086; Fax: 212-348-2474; E-mail: enver.akalin{at}msnyuhealth.org
| Abstract |
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Design, setting, participants, & measurements: Thirty-five complement-dependent cytotoxicity T cell cross-match–negative but complement-dependent cytotoxicity B cell and/or flow cytometry cross-match–positive kidney transplant recipients were treated with high-dosage intravenous Ig plus Thymoglobulin induction treatment. Donor-specific antibody strength was stratified as strong, medium, or weak by Luminex flow beads. Group 1 patients had weak/moderate and group 2 strong donor-specific antibodies
Results: Whereas no group 1 patients had acute rejection, 66% of group 2 had acute rejection (44% antibody-mediated rejection, 22% cellular rejection). The protocol was then changed to the addition of peritransplantation plasmapheresis to patients with strong donor-specific antibodies (group 3). This change resulted in a dramatic decrease in the acute rejection rate to 7%. During a median 18 mo of follow-up, patient survival was 100, 100, and 93% and graft survival was 100, 78, and 86% in groups 1, 2, and 3, respectively. During follow-up, 17 (52%) patients lost donor-specific antibodies completely, and 10 (30%) lost some of donor-specific antibodies and/or decreased the strength of existing donor-specific antibodies.
Conclusions: These results indicated that in patients with strong donor-specific antibodies, the addition of plasmapheresis to high-dosage intravenous Ig decreases the incidence of acute rejection. The majority of the patients, whether they received intravenous Ig alone or with plasmapheresis, lost their donor-specific antibodies during follow-up.
| Introduction |
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Whereas CDC T cell cross-match positivity is an absolute contraindication to kidney transplantation, the clinical significance of CDC B cell or flow cytometry (FC) T and/or B cell cross-match positivity are less clear. Most studies have demonstrated that CDC T cell cross-match–negative but CDC B or FC T/B cell cross-match–positive patients with DSA are at higher risk for developing acute cellular, antibody-mediated, and chronic rejection and graft loss (9,10). The role of desensitization protocols for these patients has not been studied in a large cohort. We previously reported our initial experience using low-dosage IVIG (300 mg/kg) and Thymoglobulin induction treatment in 15 patients (11,12). Because of early AMR in three patients, the IVIG dosage was increased to a total of 2.0 mg/kg in subsequent patients. Now, we present our experience in CDC T cell–negative but CDC B cell or FC T and/or B cell cross-match–positive kidney transplant recipients with DSA, who were stratified according to mean fluorescence indices of Luminex flow beads. The results showed that patients with strong DSA were at much higher risk for developing acute AMR early after transplantation, and the addition of peritransplantation PP to high-dosage IVIG and Thymoglobulin treatment significantly decreased the incidence of AMR. The majority of the patients, whether they received IVIG alone or with PP, lost DSA during follow-up.
| Materials and Methods |
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Cross-Match Methods and Detection of Anti-HLA Antibodies
The CDC assay was performed with the anti-human globulin method. The FC cross-match detected human IgG antibodies bound to the target T and B lymphocytes labeled with Becton-Dickinson (BD Biosciences, San Jose, CA) Mouse Anti-human antibodies (CD3-PerCP and CD19-PE). The samples were run on a Becton-Dickinson FacsCalibur flow cytometer and quantified by median fluorescence intensity (MFI). The difference between these two samples determined the channel displacement (Chd). Cross-matches with a Chd of
40 for T lymphocytes and
150 for B lymphocytes were interpreted as positive.
Anti-HLA antibodies were studied by Luminex Flow Beads (LABScreen products; One Lambda, Canoga Park, CA) that use a panel of color-coded beads, which were coated with purified HLA antigens. Test serum was incubated with LABScreen beads, and HLA antibodies bound to the beads labeled with R-Phycoerythrin–conjugated goat anti-human IgG (One Lambda). Beads were analyzed with the Luminex 100 flow analyzer and IS V2.3 software. Antigen-specific analysis was performed, and the strength of the reaction was assigned (HLA Visual V2.0; One Lambda). The strength of the reactions was graded by two methods: Ratio (sample test bead/sample negative control bead)/(negative serum test bead/negative serum negative control bead) for the first five patients or baseline (sample test bead – sample negative control bead) – (negative serum test bead – negative serum negative control bead) for the remaining 30 patients. The following strengths were assigned to the reactions: Strong, median ratio
10 or median baseline
6000; moderate, median ratio
5 and <10 or median baseline
4000 to 5999; or weak, median ratio
1.5 and <5 or median baseline
1500 to 3999.
Histopathology
Biopsies were performed for an increase in creatinine level and/or proteinuria. All biopsy specimens were examined by light microscopy and C4d staining. C4d staining was performed on paraffin sections using polyclonal rabbit anti-C4d antibody (Rabbit polyclonal; American Research Products, Inc., Belmont, MA). The histologic lesions and AMR were classified and scored according to the Banff classification (13,14). There are three types of acute AMR: Type 1, ATN-like, acute tubular injury with a few tubulointerstitial neutrophil infiltrates; type 2, mainly involves glomeruli with neutrophils and monocyte infiltration (glomerulitis) and fibrin microthrombi, resembling thrombotic microangiopathy; and type III, arterial inflammation with or without fibrinoid changes.
Immunosuppressive Treatment Protocol
All patients received Thymoglobulin (1.5 mg/kg per d for 5 d) induction treatment, along with tacrolimus, mycophenolate mofetil, and a steroid taper. Corticosteroids were initiated intraoperatively at 500 mg of methylprednisolone, followed by an oral prednisone taper to 10 mg/d by 2 to 3 mo and 5.0 mg/d by 4 to 6 mo after transplantation. All patients received mycophenolate mofetil at 1.0 g twice a day. Tacrolimus was started at 0.1 to 0.2 mg/kg twice a day, and the dosage was adjusted to keep trough levels 10 to 15 ng/ml for the first 3 mo, 8 to 12 ng/ml between 4 and 6 mo, and 5 to 8 ng/ml thereafter. All patients received valganciclovir 450 mg/d for 6 mo and trimethoprim/sulfamethoxazole for 3 mo.
All patients received high-dosage IVIG (1.0 g/kg during transplant surgery and 500 mg/kg on each of postoperative days 1 and 2). After early AMR was observed in four patients with strong class I DSA, all patients with strong class I DSA received PP. Living-donor kidney transplant candidates with strong class I DSA received four to eight sessions of pretransplantation PP over 2 to 3 wk and underwent transplantation after their DSA strength decreased to moderate or weak. Deceased-donor kidney transplant recipients with DSA received three sessions of PP every other day starting on postoperative day 1.
AMR was treated with pulse methylprednisolone 250 mg for 3 d; PP four to eight sessions, with each session followed by IVIG 500 mg/kg; and a single dose of rituximab (375 mg/m2) after PP and IVIG treatment completed. Acute cellular rejection grade Ia and Ib was treated with pulse methylprednisolone 250 mg for 3 d, and rejection grade IIa or higher was treated with Thymoglobulin 1.5 mg/kg for 5 to 7 d.
| Results |
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Acute Rejection and Patient and Graft Survival
Whereas four (80%) of five patients who had strong class I DSA and were not receiving PP (group 2) had acute rejection within 10 d after transplantation (three AMR and one cellular rejection), none of the patients who had weak- and/or moderate-strength DSA and were not receiving PP (group 1) had an acute rejection episode (Table 2). After the addition of PP to the patients with strong class I DSA (group 3), none of the four living-donor recipients and only one of 10 patients who received a deceased-donor transplant developed acute AMR (7%). This patient had three strong class I and two class II DSA. Two of the four patients who had strong class II DSA and were receiving high-dosage IVIG without PP developed acute rejection. Overall, six (66%) of nine group 2 patients with strong DSA (class I and/or II) had acute rejection (44% AMR and 22% cellular rejection). After this experience, we decided to perform peritransplantation PP in all patients with strong DSA, whether class I or class II.
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During a median 16 mo of follow-up (range 8 to 35 mo) in group 1 and 22 mo (range 8 to 31 mo) in group 2, none of the patients died (100% patient survival; Table 3). In group 3, during a median 12 mo of follow-up (range 6 to 18 mo), one patient died as a result of gastrointestinal bleeding with stable kidney function (93% patient survival). Whereas all group 1 patients had functioning allografts (100% graft survival), one patient in group 2 lost the allograft as a result of acute AMR at 3 mo and the other as a result of sepsis and acute tubular necrosis 10 mo after transplantation (78% graft survival). In group 3, one deceased-donor kidney transplant recipient lost the allograft as a result of donor-related factors. This patient had four follow-up biopsies after transplantation, which showed progressive fibrosis, but all were negative for acute rejection and C4d staining (86% graft survival).
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Donor-Specific Anti-HLA Antibodies
DSA were studied after transplantation by Luminex Flow Beads in all groups 2 and 3 patients and 10 of 12 group 1 patients, and the results of DSA at the last clinic visit are shown in Table 2. Seven (70%) group 1 patients lost DSA completely, one patient lost all class I DSA, and only two patients continued to have weak DSA. In group 2, four (44%) patients lost DSA completely and three patients lost some of their DSA and/or decreased the strength of DSA. In group 3, six (43%) patients lost DSA completely, two patients all class I DSA, and four patients lost some DSA and/or decreased the strength of DSA. Overall, in 33 patients whose posttransplantation DSA were studied, 17 (52%) lost their DSA completely and 10 (30%) partially.
We analyzed the Luminex data for non-DSA. Our patients were highly sensitized with a median PRA level of 67 (range 14 to 100) and multiple anti-HLA antibodies, which makes difficult to interpret the outcome of each non-DSA specifically; however, the mean MFI of non-DSA decreased after transplantation in all three groups. The decrease in MFI of class I non-DSA was 34% in group 1 (from 2080 ± 2228 to 1383 ± 1402), 24% in group 2 (from 6040 ± 2887 to 4567 ± 3825), and 38% in group 3 (from 7707 ± 3792 to 4781 ± 3528). The decrease in MFI of class II non-DSA was 64% in group 1 (from 5625 ± 2213 to 1900 ± 1980), 31% in group 2 (from 8333 ± 3830 to 5714 ± 4645), and 24% in group 3 (from 9429 ± 3309 to 7128 ± 2650).
Complications
One patient each in groups 1 and 2 had non–tissue-invasive cytomegalovirus disease and responded to treatment, whereas none in group 3 had cytomegalovirus infection. One patient in the group 3 developed biopsy-proven polyoma nephropathy 14 mo after transplantation and has stable renal function with a creatinine level of 1.8. None in groups 1 and 2 developed polyoma nephropathy. One patient in group 1 developed cryptococcal meningitis 9 mo after transplantation and responded to treatment.
| Discussion |
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The acute rejection rate has been >30% in patients who receive desensitization protocols, and it is still not clear which protocol (high-dosage IVIG, PP/low-dosage IVIG), what type of induction treatment (Thymoglobulin, anti–IL-2R antibodies, alemtuzumab), or addition of rituximab is better for the prevention of early acute AMR. The Cedars-Sinai group using high-dosage IVIG reported the outcome of 97 kidney transplant recipients in terms of two types of induction treatment (3). Although 2-yr graft survival was 84% in daclizumab-treated and 90% in Thymoglobulin-treated patients, acute rejection rate was 36% (22% AMR) and 31% (21% AMR), respectively. These results indicated that neither agent was effective in reducing the incidence of acute AMR; however, the authors did not report DSA of the patients, and it is not clear whether patients with positive cross-match but negative DSA received transplantation. Thymoglobulin is a more potent induction agent compared with anti–IL-2R antibodies in terms of preventing acute rejection (17). Its efficacy may relate to effects on B cells, such as the ability to induce apoptosis of naive and memory B cells in vitro (18) and treat acute AMR in vivo (19).
A low-dosage IVIG with PP protocol has been used mainly in living-donor recipients. Schweitzer et al. (7) reported a 36% acute rejection rate by using this protocol. Stegall et al. (8) used several methods in CDC T cell cross-match–positive recipients, including rituximab, a chimeric murine/human mAb that binds to CD20 on pre-B and mature B lymphocytes. Thirteen patients received high-dosage IVIG (group 1); 32 patients received PP, low-dosage IVIG, and rituximab (group 2); and 16 patients received PP, low-dosage IVIG, rituximab, and pretransplantation Thymoglobulin (group 3). The acute rejection rate was 80% in group 1, 37% in group 2, and 29% in group 3. The authors concluded that no regimen was completely effective in preventing AMR. A significant decrease in AMR incidence in our patients with the addition of PP indicated that use of high-dosage IVIG is better than the low-dosage IVIG plus PP combination, probably because of increased immunomodulatory effects with high-dosage IVIG.
The clinical significance of positive CDC B cell or FC T or B cell cross-match results on graft outcome is controversial. Whereas some studies did not find any effect on graft outcome, most studies demonstrated increased acute and chronic rejection and decreased graft survival (9,10). The main reason for the controversial outcomes in the literature is the lack of studies to confirm DSA. Le Bas-Bernardet et al. (20) showed that only 23% of B cell cross-match–positive patients had DSA and demonstrated lower allograft survival, whereas cross-match–positive patients without DSA had similar graft survival to that of B cell cross-match–negative control subjects. Bray et al. (21) showed that whereas patients with pretransplantation-positive FC cross-match and 0% FlowPRA had 100% 1-yr graft survival, it was only 40% in patients with both FC cross-match positivity and DSA by FlowPRA. Our study demonstrates the importance of treating these DSA with an effective desensitization protocol despite the negative pretransplantation CDC T cell cross-match. Some patients may even have DSA without positive CDC and FC cross-match result. Patel et al. (22) reported that four of 20 patients with pretransplantation DSA but negative CDC and FC cross-match developed acute AMR. Three patients in our series also had DSA without any cross-match positivity.
One of the long-term problems in patients who receive desensitization protocol is TGP and chronic AMR. Two recent studies by Gloor et al. (23) and Anglicheau et al. (24) documented 22 and 28% TGP at 12-mo protocol biopsies of patients who received desensitization protocols, respectively. Three of our patients who had early AMR developed TGP 3 to 12 mo after transplantation. Because of lack of baseline as well as protocol biopsies, it is difficult to determine the true incidence of CAN and TGP in our patients.
Montgomery et al. (25) followed up DSA of 49 kidney transplant recipients who underwent a desensitization protocol of PP/low-dosage IVIG and demonstrated that 63% lost DSA at the end of the treatment and 89%
2 mo after the end of treatment; however, the Mayo Clinic group showed that the majority of their desensitized patients continued to have low levels of DSA (26). In our study, 52% of patients lost DSA completely, and 30% lost some of their DSA or decreased DSA strength, indicating that both methods, high-dosage IVIG alone and PP/high-dosage IVIG, are effective in downregulating antibody production. Not only DSA but also the mean MFI of non-DSA decreased in all three groups, suggesting a nonspecific decrease in overall antibody production.
| Conclusions |
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| Disclosures |
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| Acknowledgments |
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| Footnotes |
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Received November 29, 2007. Accepted February 13, 2008.
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