Effect of Different Rituximab Doses on B Cell Count, Anti-A/B Antibody Titer, Graft Function, and Infectious Complications in ABO-Incompatible Renal Transplantation: A Prospective Study.

BACKGROUND: ABO-incompatible kidney transplantation (ABOiKT) has been accepted as a viable and cost-effective modality with outcomes comparable to ABO-compatible transplants, but there is a concern regarding higher infectious complications in ABOiKT because of the heightened immunosuppression. The desensitization protocol normally includes antibody removal, B cell depletion by rituximab (RTX), and immunomodulation with intravenous immunoglobulin. Efforts have been made over the years to decrease the dose of RTX in an effort to decrease the infective complications. There is limited literature about the minimum effective dose of RTX, which can cause an effective B cell depletion. This prospective study was designed to correlate the RTX dose with peripheral absolute B cell count, graft function, graft and patient survival, and infective complications. METHODS: This study included 52 adult ABOiKT recipients with anti-A/B antibody titer up to a maximum of 1:512. The participants were divided into 2 groups of 26 each according to the RTX dosage used: Group A received 100 mg/patient, and Group B received 200 mg/patient. RTX was given 14 days prior to transplant after B cell measurement by flow cytometry. The outcomes were compared after 1 year of follow-up. RESULTS: Both the dosages effectively depleted the absolute B cell count. Although patient survivals, graft survival, graft function, acute rejection episodes, and post-transplant hospital stay were similar in both groups, infective complications were significantly higher in group B. CONCLUSION: A low dose (100 mg/patient) of RTX produces effective depletion of B cells while lowering the infective complications in ABOiKT.

Long-Term Outcome of ABO-Incompatible Kidney Transplantation in Patients Treated With Low-Dose Rituximab Regimen.

BACKGROUND: Introduction of rituximab in the desensitization protocols for ABO-incompatible (ABOI) kidney transplantation (KTX) has afforded excellent results. However, the acceptability of minimal dosage of rituximab in these protocols remains to be defined. METHODS: Sixty-three patients who underwent ABOI KTX were included in this study. The desensitization protocol consisted of plasmapheresis, tacrolimus, mycophenolate mofetil, methylprednisolone, intravenous immunoglobulin, basiliximab, and low-dose rituximab (100 mg/body). We evaluated the efficacy, safety, and long-term outcome of this protocol (group R, n = 39) and compared them with those of patients who underwent splenectomy (group S, n = 24). RESULTS: Graft and patient survival at 10 years after KTX were comparable between the groups (94.4% [group R] vs 95.4% [group S] and 94.6% [group R] vs 95.8% [group S], respectively). The incidence of acute antibody-mediated rejection (AAMR) was similar in the 2 groups (10.2% vs 12.5%). There were no significant differences in the incidence of chronic active antibody-mediated rejection. Of the patients, 7 developed AAMR and 3 of these patients (1 in group R and 2 in group S) lost their grafts. There were no significant differences in the incidence of chronic active antibody-mediated rejection. The incidence of postoperative cytomegalovirus infection in group R was significantly lower than that in group S. Furthermore, the incidence of postoperative late-onset neutropenia was low in group R. CONCLUSIONS: A low-dose rituximab regimen for ABOI KTX is acceptable for preventing AAMR with a low incidence of delayed adverse events.

Effect of Rituximab Used as Induction in Patients with ABO Mismatch Kidney Transplant: A Systematic Review and Meta-analysis.

INTRODUCTION: ABO-incompatible living kidney transplantation (ABOILKT) has steadily become more widespread. However, the optimal immunosuppressive regimen for ABOILKT remains uncertain. We aimed to determine the outcomes according to dose of rituximab induction. METHODS: We conducted a systematic review and meta-analysis using random-effects modeling. We searched the following databases for all studies published through May 15, 2019: Cochrane Central Register, OVID MEDLINE, EMBASE, and PubMed. We reviewed all relevant reviews, registered trials, and relevant conference proceedings to compare clinical outcomes and survival according to dose of rituximab as induction in kidney transplantation. RESULTS: Five trials with a total of 390 patients were included. Glomerular filtration rates, graft loss, antibody mediated rejection, T cell mediated rejection, fungal infection (Candida), and patient survival rates did not differ between the 200 mg single dose and 375 mg/m2 in rituximab groups. However, incidence rate of infection 0.470 (95% confidence interval [CI], 0.264 to 0.838) had a lower result than the 200 mg rituximab group. CONCLUSIONS: The using of a 200 mg single dose of rituximab induction in ABOILKT has not only the same results for rejection, graft survival, and patient survival but also low incidence of infection after transplantation.

Outcome of ABO Blood Type-Incompatible Living-Related Donor Kidney Transplantation Under a Contemporary Immunosuppression Strategy in Japan.

BACKGROUND: Because of the serious donor shortage in Japan, there is an increasing need for ABO blood type-incompatible kidney transplantation (ABOi-KT) in living-related donor kidney transplantation. We evaluated the outcomes of ABOi-KT performed at our hospitals using a contemporary immunosuppression strategy with low-dose rituximab. PATIENTS AND METHODS: Between June 2006 and April 2019, 107 patients underwent living-related donor kidney transplantation at our hospitals. The patients were divided into ABO-compatible (ABOc) and ABOi groups. The basic immunosuppression regimen differed between the 2 groups in the use of low-dose rituximab and therapeutic apheresis in the ABOi group. We compared graft survival, patient survival, rejection, viral infection, and posttransplant renal function between the 2 groups. RESULTS: Of 107 recipients, 37 (35%) underwent ABOi-KT. The 5-year graft survival rates in the ABOc and ABOi group were 91% and 100%, respectively. The Kaplan-Meier analyses showed no difference in graft survival (P = .168) or patient survival (P = .873) between the groups. Biopsy-proven rejection in the ABOc and ABOi groups was observed in 13 (19%) and 7 (19%) patients, respectively (P = .965), and viral infection was observed in 21 (30%) and 10 (27%) patients (P = .747), respectively. Renal function by estimated glomerular filtration rate from 1 week to 5 years after transplantation was similar in both groups. CONCLUSIONS: The outcomes of ABOi-KT with low-dose rituximab were comparable with those of ABOc-KT at our hospitals. ABOi-KT with proper immunosuppression may be an option to help resolve the severe donor shortage in Japan.

Early Steroid Withdrawal Protocol With Basiliximab and Rituximab in ABO-Incompatible Kidney Transplant Recipients.

OBJECTIVES: Corticosteroids remain an important component of immunosuppressive regimens in high-risk kidney transplants. In this study, we investigated the efficacy of early steroid withdrawal with basiliximab and rituximab in ABO-blood type incompatible (ABO-i) recipients of kidney transplants. METHODS: Between 2008 and 2019, 15 patients underwent ABO-i kidney transplantation. Seven of the 15 patients were treated with a steroid maintenance protocol and the remaining 8 with an early steroid withdrawal protocol. The immunosuppressive protocol consisted of tacrolimus, mycophenolate mofetil, and methylprednisolone (MP), with basiliximab administered as induction therapy. Rituximab was administered as a single 200-mg dose 1 to 4 weeks before kidney transplantation. Two to 4 sessions of either double-filtration plasmapheresis or regular plasmapheresis or both were performed to remove anti-AB antibodies before transplantation. During surgery, MP was administered at a dose of 500 mg; thereafter, the dosage was tapered rapidly, and the drug was discontinued on day 14 post transplant. RESULTS: In the steroid maintenance group, 2 patients experienced acute antibody-mediated rejection (AMR). One patient with severe AMR had graft loss on postoperative day 4. Patient and graft survival rates in the steroid maintenance group were 100% and 86%, respectively. MP was successfully withdrawn in the steroid withdrawal group. In this group, there was no biopsy-proven rejection. Patient and graft survival rates were 100%, and when last measured, serum creatinine level ± SD was 1.6 ± 0.8 mg/dL. CONCLUSIONS: Our protocol successfully enabled the early withdrawal of steroids in recipients of ABO-i grafts; however, further follow-up is necessary to confirm our results.

Analysis of the prevalence of systemic de novo thrombotic microangiopathy after ABO-incompatible kidney transplantation and the associated risk factors.

OBJECTIVES: To analyze the prevalence of systemic de novo thrombotic microangiopathy in ABO-incompatible kidney transplantation and risk factors associated with this condition. METHODS: A total of 201 patients who received living-donor kidney transplantation (114 patients with ABO-identical kidney transplantation and 87 patients with ABO-incompatible kidney transplantation) were retrospectively analyzed. Systemic de novo thrombotic microangiopathy was diagnosed clinically according to the presence of thrombocytopenia with microangiopathic hemolytic anemia and pathological findings of thrombotic microangiopathy. Anti-A and anti-B antibodies were purified from human plasma, and these antibodies' bindings to human kidney were investigated in vitro. RESULTS: ABO-incompatible kidney transplantation was a significant risk factor of systemic de novo thrombotic microangiopathy (odds ratio 55.9, 95% CI 1.8-8.9, P < 0.001) after transplantation. Multivariate logistic regression analysis showed that non-use of mycophenolate mofetil, pretreatment immunoglobulin G antibody titer ≥64-fold and pretransplant immunoglobulin M antibody titer ≥16-fold were significant risk factors for systemic de novo thrombotic microangiopathy in ABO-incompatible kidney transplantation. Microvascular inflammation of 1-h post-transplant biopsy could be observed more frequently in thrombotic microangiopathy patients than in non-thrombotic microangiopathy patients. Anti-A and anti-B antibodies purified from human plasma showed a strong in vitro reaction against human kidney when the antibody titer was ≥16-fold. CONCLUSIONS: Antibody titer should be decreased to ≤16-fold until the day of ABO-incompatible kidney transplantation by desensitization therapy including mycophenolate mofetil. The 1-h biopsy results might help to diagnose systemic de novo thrombotic microangiopathy.

Induction of Accommodation by Anti-complement Component 5 Antibody-based Immunosuppression in ABO-incompatible Heart Transplantation.

BACKGROUND: Plasmapheresis in combination with immunoglobulin and rituximab is often used to induce accommodation in ABO-incompatible (ABOi) living-donor transplantation; however, this regimen cannot be applied to cases of ABOi deceased-donor transplantation. Here, we investigated whether an anti-complement component 5 (C5) antibody-based regimen can induce accommodation in ABOi heart transplantation. METHODS: Both IgM and IgG anti-blood type A antibodies were induced in wild-type mice by sensitization using human blood type A antigen. Heterotopic ABOi heart transplantation was performed from human blood type A-transgenic C57BL/6J mice to sensitized wild-type DBA/2 mice. RESULTS: Either anti-C5 antibody or conventional triple immunosuppressants (corticosteroid, tacrolimus, mycophenolate mofetil) alone did not induce accommodation in majority of ABOi heart allografts, whereas their combination induced accommodation in more than 70% of cases despite the presence of anti-A antibodies. The combination therapy markedly suppressed the infiltration of T cells and macrophages into ABOi allografts, despite mild deposition of IgG and C4d. T-cell activation and differentiation into Th1, Th2, and Th17 cells were suppressed along with CD49dCD4 T and follicular helper T cells in the combination treatment group. CD24 B cells, including both CD24CD23 marginal zone B cells and CD24CD23 T2-marginal zone B cells, were increased in the accommodation group. CONCLUSIONS: C5 inhibitor-based immunosuppression induced accommodation in murine ABOi heart transplantation, presenting a promising strategy for ABOi deceased-donor transplantation.

Percentage of CD19+ Cells in Peripheral Blood Lymphocytes After Rituximab-Based Desensitization as a Predictor of Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation.

BACKGROUND: Rituximab (RIT) is effective as a part of the desensitization therapy before ABO-incompatible kidney transplantation (ABOi-KTx), and a single dose of RIT at 375 mg/m2 or less is recommended. However, adequate RIT dose recommendations have not yet been established for individual recipients. Therefore, we evaluated the relationship between the proportion of B cells in peripheral blood and acute antibody-mediated rejection (AAMR). METHODS: Forty-four consecutive ABOi-KTx recipients were enrolled in this retrospective study. Before transplantation, subjects were treated with RIT at various doses, ranging from 65 to 400 mg/body (46-263 mg/m2), followed by plasmapheresis and intravenous immunoglobulin as a desensitization therapy. The percentage of CD19+ cells in the total peripheral blood lymphocytes population (%CD19) was determined the day before transplantation. Transplant recipients were divided into 2 groups according to pretransplant %CD19, as follows: low %CD19 group, ≤ 1.2% (n = 35) and high %CD19 group, > 1.2% (n = 9). The relationship between %CD19 and incidence of AAMR was evaluated, and the predicting factors for AAMR incidence were determined by univariate and multivariate analyses. RESULTS: The incidence of AAMR was significantly higher in the high %CD19 group than in the low %CD19 group (44.4% vs 5.7%, P = .006). Furthermore, multivariate analysis showed that %CD19 > 1.2% was the only independent factor to predict AAMR, with an odds ratio of 14.31 (P = .038). CONCLUSION: High %CD19 values after rituximab administration in ABOi-KTx recipients implies insufficient depletion of B cells, which can lead to AAMR.

Isolated V-Lesion in an ABO-Incompatible Kidney Transplant Recipient Receiving Rituximab.

We report an ABO-incompatible kidney transplant performed on a 69-year-old female patient, whose donor was her 69-year-old husband. The patient received an immunosuppressive protocol using rituximab without splenectomy. Renal biopsy was done on posttransplant day 8 due to poor early graft function, and an isolated v-lesion was found, which responded to steroid pulse therapy and gusperimus hydrochloride administration. Our results indicate that isolated v-lesions can occur in ABO-incompatible kidney transplant recipients receiving rituximab and that this finding should be treated as acute rejection. To our knowledge, this is the first report of an isolated v-lesion in an ABO-incompatible kidney transplant recipient who had been administered rituximab.

Safety and Efficacy of Induction Therapy With Thymoglobulin in AB0-Incompatible Kidney Transplantation.

INTRODUCTION: Data suggest an additional role of T cells in antibody-mediated rejections. In 2001 a protocol for AB0-incompatible kidney transplantation based on B-cell-depleting anti-CD20 antibody rituximab, antigen-specific blood group IgG immunoadsorption, intravenous immunoglobulins, and triple immunosuppression was introduced in Europe, which used induction therapy with the use of interleukin-2 receptor antibody (IL2-RA) basiliximab. We used thymoglobulin in AB0-incompatible patients as induction in the face of high immunologic risk. METHODS: We retrospectively evaluated a cohort of 9 AB0i living donation (LD) recipients from 2011 to 2014. Desensitization included blood group-specific immunoadsorption. Eighteen AB0-compatible LD recipients receiving induction therapy with thymoglobulin served as control subjects. Another control group consisted of 18 AB0-compatible LD recipients receiving basiliximab. Follow-up was 24 months. We captured graft function by estimating glomerular filtration rate (eGFR by Modification of Diet in Renal Disease formula), rejection episodes, and bacterial and viral infections. RESULTS: All patients experienced immediate graft function. No significant or clinical differences were observed regarding graft function, rejection rates, or infections between the groups, although there seemed to be slightly higher cytomegalovirus infection rates due to preemptive therapy strategy. CONCLUSIONS: Thymoglobulin appears to be similar in safety and efficacy to IL-2-antagonists in AB0i kidney transplantation.

Late Steroid Withdrawal Following AB0-Incompatible Renal Transplantation.

BACKGROUND: Current evidence on steroid withdrawal following AB0-incompatible (AB0i) renal transplantation is low. We compared clinical outcomes of patients who agreed to late steroid withdrawal and patients who remained on steroid treatment. METHODS: Steroid withdrawal was carried out in 11 patients at ≥12 months after transplantation (group W). For comparison, we analyzed 19 patients who remained on triple immunosuppression including steroids (group M). Minimum follow-up was 24 months following transplantation and 12 months after steroid withdrawal. RESULTS: Baseline characteristics, including observation times, were not different between groups W and M. Graft survival was 100% in group W compared with 84% (16/19) in group M (P = .15). In group M, 1 patient experienced graft failure because of suspected antibody-mediated rejection (ABMR) following temporary cessation of mycophenolate treatment after a diagnosis of cryptococcal pneumonia. Two patients died with functioning graft because of sepsis. In group W, we observed 1 episode of ABMR following steroid withdrawal. At the end of follow-up, estimated glomerular filtration rates (eGFR) were 54 (19-91) versus 60 (15-85) mL/min/1.73 m2 in group W versus M, respectively (P = .67). CONCLUSIONS: Late steroid withdrawal following AB0i transplantation is feasible at a moderate risk of rejection. We recommend close monitoring of renal function and HLA antibodies during and after steroid withdrawal. On the other hand, the occurrence of severe infections causing death and graft loss in patients on triple maintenance immunosuppression including steroids should remind us to consider the overall immunosuppressive burden.

Eculizumab for Prevention of Antibody-Mediated Rejection in Blood Group-Incompatible Renal Transplantation.

Antibody-mediated rejection (AMR) is one of the leading causes of allograft failure especially in patients undergoing ABO-incompatible (ABOi) renal transplantation. We hypothesized that complement inhibition with eculizumab, a C5 inhibitor, would protect against AMR and maintain graft function in ABOi renal transplant recipients. Four patients undergoing living donor kidney transplant from ABOi donors were treated with a 9-week eculizumab course without therapeutic plasma exchange, intravenous immunoglobulin, or splenectomy. All patients had successful transplants and have normal graft function at the time of last follow-up. There were no cases of AMR or acute cellular rejection. Of note, 2 patients were transplanted despite persistent ABO antibody titers of 1:32, conventionally considered a contraindication to proceed in standard protocols. Eculizumab is a promising option to prevent AMR with ABOi renal transplantation without the need for splenectomy, post-transplant therapeutic plasma exchange, and intravenous immunoglobulin. Future multicenter studies are needed to determine long-term efficacy and safety.

Four-Way Kidney Exchange Transplant With Desensitization Increases Access to Living-Donor Kidney Transplant: First Report From India.

OBJECTIVES: This study reports our experience of the first 4-way kidney exchange transplant combined with desensitization in India, which allows increased access to living-donor kidney transplant for sensitized patients. MATERIALS AND METHODS: Four-way kidney exchange transplant procedures were approved by the ethics committee of our institution and the Organ Transplantation Authorization Committee of state governments of India (as per the Transplantation of Human Organs Act of India). The protocols conformed to Declaration of Istanbul principles and the ethical guidelines of the 1975 Helsinki Declaration. Written informed consent was obtained from patients, donors, and their guardians. RESULTS: In April 2016, our transplant team completed simultaneous 4-way kidney exchange transplant procedures without any medical (rejection and infections) or surgical complications. Reasons for being included for kidney exchange transplant were ABO incom-patible (2 recipients) and sensitization (2 recipients). All 4 recipients had stable graft function with no proteinuria and donor-specific antibody at 11-month follow-up on standard triple immunosup-pression. Patient and graft survival rates were both 100%. CONCLUSIONS: To the best of our knowledge, this is the first single-center report of 4-way kidney exchange transplant combined with desensitization from India. This procedure has the potential to expand living-donor kidney transplant in disadvantaged groups (eg, sensitized patients). Recipients who are hard to match due to high panel reactive antibody and difficult to desensitize due to strong donor-specific antibodies can receive a transplant with a combination of kidney exchange and desensitization. Our study suggests that 4-way kidney exchange transplant can be performed in developing countries (India) similar to that shown in programs in developed countries with team work, kidney exchange registry, and counseling.

First case report of using Ofatumumab in kidney transplantation AB0 incompatible. / PRIMO CASE REPORT DI UTILIZZO DELL' OFATUMUMAB NEL TRAPIANTO RENALE AB0 INCOMPATIBILE.

Modern methods for desensitization protocol rely heavily on combined apheresis therapy and Rituximab, a chimeric (murine and human) anti-CD20 antibody used in AB0 incompatible kidney transplants. Severe infusion related reactions due to the administration of Rituximab are reported in 10% of patients. These adverse reactions may hinder the completion of the desensitization protocol. Therefore, it's useful to test alternative B cell depleting therapies. Our clinical case focuses on a 41-year-old male who developed an adverse infusion reaction following the administration of Rituximab and was given Ofatumumab as an alternative treatment. Ofatumumab is a fully humanized monoclonal anti-CD20 antibody. As a fully humanized antibody, Ofatumumab may avoid immunogenic reactions. The patient tolerated the administration of the drug showing no signs of adverse side effects and with good clinical efficacy. Our case report suggest that Ofatumumab is a valid alternative B cell depleting agent.

Beneficial Effects of High-Dose Mizoribine on ABO-Incompatible Living-Related Kidney Transplantation: Two-Year Results by a Japanese Multicenter Study.

BACKGROUND: Mizoribine (MZ) has been developed as an immunosuppressive agent in Japan, but it has a less-potent immunosuppressive effect up to 3 mg/kg/d. In the previous study, a Japanese multicenter study, we reported that high-dose MZ, at 6 mg/kg/d, with a calcineurin inhibitor was effective and safe in reducing the frequency of cytomegalovirus (CMV)-related events in ABO-incompatible (ABO-i) living-related kidney transplantation (LKT). In the present study, therefore, we investigated the effects of high-dose MZ with a CNI in ABO-i LKT recipients in a Japanese multicenter study. METHODS: A total of 37 patients were treated with high-dose MZ (6 mg/kg), a CNI (cyclosporine [CsA] or tacrolimus [Tac]), basiliximab (Bas), rituximab (Rit), and corticosteroids. CsA was started at a dose of 7 mg/kg to maintain blood levels [200 ng/mL (C0), 6000 ng-h/mL (AUC 0-9)]. Tac was started at a dose of 0.2 mg/kg to maintain blood levels [8-10 ng/mL (C0), 100 ng-h/mL (AUC 0-9)]. Bas (20 mg/body) was administrated on day 0 and day 4 after transplantation. Rit (100-200 mg/body) was administrated on day -14 and day -7 before transplantation. MZ was adjusted to maintain target C0 levels of 1.5 to 2.0 µg/mL. RESULTS: Patient and graft survival rates for 2 years were 100% in the CsA group (n = 22) and 93.3% in the Tac group (n = 15) (not significant, NS). Overall incidence of acute rejection for 2 years was 22.7% in the CsA group and 26.7% in the Tac group. Mean serum creatinine levels at 2 years were 1.29 ± 0.2 mg/dL in the CsA group and 1.21 ± 0.34 mg/dL in the Tac group (NS). The incidence of CMV disease was 0% in both groups, and positive rates of CMV antigenemia were 50.0% and 26.7% in the CsA and Tac groups, respectively (NS). Mean serum uric acid levels were 5.5 ± 1.3 mg/dL and 6.4 ± 1.2 mg/dL at 2 years (NS) in the CsA and Tac groups, respectively. CONCLUSIONS: A high-dose MZ regimen including calcineurin inhibitor (CsA or Tac), Bas, Rit, and steroids was effective and safe in reducing the frequency of CMV-related events in ABO-i LKT.

First successful perinatal management of pregnancy after ABO-incompatible liver transplantation.

Many papers have reported on pregnancy and delivery after liver transplantation, but there have been no reports on pregnancy after ABO-incompatible liver transplantation. This paper reports the first successful pregnancy and delivery of a newborn after ABO-incompatible liver transplantation for fulminant hepatic failure. The patient was a 39-year-old female. She had an ABO-incompatible liver transplantation, donated from her husband, due to subacute fulminant hepatitis of unknown etiology. She was taking tacrolimus, methylprednisolone, and mizoribine orally for the maintenance of immunosuppression at the time of discharge. She was discharged uneventfully on postoperative day 38 without any rejection episodes. At 1 year and 6 mo after transplantation, she indicated a wish to become pregnant. Therefore, treatment with mycophenolate mofetil was interrupted at that time. After two miscarriages, she finally became pregnant and delivered transvaginally 3 years after the transplantation. All of the pregnancies were conceived naturally. The newborn was female with a birth weight of 3146 g; the Apgar scores were 9 and 10. Delivery was performed smoothly, and the newborn exhibited no malformations. The mother and the newborn were discharged uneventfully. We suggest that pregnancy is possible for recipients after ABO-incompatible liver transplantation.

Optimal dosage regimen for rituximab in ABO-incompatible living donor liver transplantation.

BACKGROUND: Rituximab has greatly improved the outcomes of ABO-incompatible living donor liver transplantation (ABO-I LDLT). To clarify the optimal regimen for rituximab in adult ABO-I LDLT, a multicenter study was conducted in Japan. METHODS: Clinical data of 33 adult patients undergoing ABO-I LDLT at 15 centers in 2013 were retrospectively corrected. RESULTS: The targeted blood type was A1 in 18, B in 14, and AB in one patient. Rituximab was administered at 7 to 48 days before LT, at a dose of 375 mg/m2 in 12 patients, 500 mg in 15 patients, 300 mg in five patients, and 100 mg in one patient. Adverse effects of rituximab were tolerable. Overall 1-year patient survival was 81%; antibody-mediated rejection (AMR) occurred in three patients (9%), two of whom died. Rituximab dose was significantly lower in patients with AMR (P < 0.001, 137 ± 61 vs. 307 ± 66 mg/m2 ). Among rituximab dose (n = 28), local infusion (n = 11), splenectomy (n = 23), prophylactic intravenous immunoglobulins (n = 12), preoperative tacrolimus (n = 9), preoperative antimetabolites (n = 21), and plasmapheresis (n = 23), only rituximab dose was a significantly favorable factor for AMR (P < 0.001). CONCLUSION: The use of rituximab at sufficient doses is recommended in adult ABO-I LDLT.

Results of a multicenter prospective clinical study in Japan for evaluating efficacy and safety of desensitization protocol based on rituximab in ABO-incompatible kidney transplantation.

BACKGROUND: Deceased organ donations are rare in Japan, with most kidney transplants performed from a limited number of living donors. Researchers have thus developed highly successful ABO-incompatible transplantation procedures, emphasizing preoperative desensitization and postoperative immunosuppression. A recent open-label, single-arm, multicenter clinical study prospectively examined the efficacy and safety of rituximab/mycophenolate mofetil desensitization in ABO-incompatible kidney transplantation without splenectomy. METHODS: Mycophenolate mofetil and low dose steroid were started 28 days pretransplant, followed by two doses of rituximab 375 mg/m2 at day -14 and day -1, and postoperative immunosuppression with tacrolimus or ciclosporin and basiliximab. The primary endpoint was the non-occurrence rate of acute antibody-mediated rejection. Patient survival and graft survival were monitored for 1 year posttransplant. RESULTS: Eighteen patients received rituximab and underwent ABO-incompatible kidney transplantation. CD19-positive peripheral B cell count decreased rapidly after the first rituximab infusion and recovered gradually after week 36. The desensitization protocol was tolerable, and most rituximab-related infusion reactions were mild. No anti-A/B antibody-mediated rejection occurred with this series. One patient developed anti-HLA antibody-mediated rejection (Banff 07 type II) on day 2, which was successfully managed. Patient and graft survival were both 100 % after 1 year. CONCLUSION: Our desensitization protocol was confirmed to be clinically effective and with acceptable toxicities for ABO-I-KTx (University Hospital Medical Information Network Registration Number: UMIN000006635).

Bortezomib decreases the magnitude of a primary humoral immune response to transfused red blood cells in a murine model.

BACKGROUND: Few therapeutic options currently exist to prevent or to mitigate transfusion-associated red blood cell (RBC) alloimmunization. We hypothesized that bortezomib, a proteasome inhibitor currently being utilized for HLA alloantibody and ADAMTS13 autoantibody reduction, may be beneficial in a transfusion setting. Herein, we utilized a reductionist murine model to test our hypothesis that bortezomib would decrease RBC alloimmune responses. STUDY DESIGN AND METHODS: Wild-type mice were treated with bortezomib or saline and transfused with murine RBCs expressing the human KEL glycoprotein. Levels of anti-KEL immunoglobulins in transfusion recipients were measured by flow cytometry. The impact of bortezomib treatment on recipient plasma cells (PCs) and other immune cells was also assessed by flow cytometry and immunofluorescence. RESULTS: After bortezomib treatment, mice had a 50% reduction in splenic white blood cells and a targeted reduction in marrow PCs. Mice treated with bortezomib before the transfusion of KEL RBCs became alloimmunized in three of three experiments, although their serum anti-KEL IgG levels were 2.6-fold lower than those in untreated mice. Once a primary antibody response was established, bortezomib treatment did not prevent an anamnestic response from occurring. CONCLUSION: To the extent that these findings are generalizable to other RBC antigens and to humans, bortezomib monotherapy is unlikely to be of significant clinical benefit in a transfusion setting where complete prevention of alloimmunization is desirable. Given the impact on PCs, however, it remains plausible that bortezomib therapy may be beneficial for RBC alloimmunization prevention or mitigation if used in combination with other immunomodulatory therapies.

Immune Desensitization Allows Pediatric Blood Group Incompatible Kidney Transplantation.

BACKGROUND: Blood group incompatible transplantation (ABOi) in children is rare as pretransplant conditioning remains challenging and concerns persist about the potential increased risk of rejection. METHODS: We describe the results of 11 ABOi pediatric renal transplant recipients in the 2 largest centers in the United Kingdom, sharing the same tailored desensitization protocol. Patients with pretransplant titers of 1 or more in 8 received rituximab 1 month before transplant; tacrolimus and mycophenolate mofetil were started 1 week before surgery. Antibody removal was performed to reduce titers to 1 or less in 8 on the day of the operation. No routine postoperative antibody removal was performed. RESULTS: Death-censored graft survival at last follow-up was 100% in the ABOi and 98% in 50 compatible pediatric transplants. One patient developed grade 2A rejection successfully treated with antithymocyte globulin. Another patient had a titer rise of 2 dilutions treated with 1 immunoadsorption session. There was no histological evidence of rejection in the other 9 patients. One patient developed cytomegalovirus and BK and 2 others EBV and BK viremia. CONCLUSIONS: Tailored desensitization in pediatric blood group incompatible kidney transplantation results in excellent outcomes with graft survival and rejection rates comparable with compatible transplants.