The Reuse of Immunoadsorption Columns in ABO-Incompatible Kidney Transplantation Is Efficient: The Swiss Experience. Transplantation. 2015;99:1030-1035. [PMID: 25340594 DOI: 10.1097/tp.0000000000000457]

Chimeric AQP4-based immunosorbent for highly-specific removal of AQP4-IgG from blood

Anti-aquaporin-4 autoantibodies (AQP4-IgG) are implicated in the pathogenesis of neuromyelitis optica spectrum disorders (NMOSD), and their removal from the blood circulation is considered to be an effective method for acute treatment. An ideal extracorporeal AQP4-IgG removal system should have high specificity, which means that it can selectively remove AQP4-IgG without affecting normal immunoglobulins. However, the conventional tryptophan immobilized column lacks sufficient specificity and cannot achieve this goal. In this study, we successfully prepared a fusion protein chimeric AQP4, which consists of the complete antigenic epitopes of human AQP4 and the constant region of scaffold protein DARPin. Chimeric AQP4 was expressed and purified from Escherichia coli, and then immobilized on agarose gel as a ligand for selective capture of AQP4-IgG immunosorbent. The prepared immunosorbent had a theoretical maximum adsorption capacity of 20.48 mg/g gel estimated by Langmuir isotherm. In vitro plasma perfusion tests demonstrated that the chimeric AQP4 coupled adsorbent had remarkable adsorption performance, and could eliminate more than 85 % of AQP4-IgG under the gel-to-plasma ratio of 1:50. Moreover, it exhibited high specificity because other human plasma proteins were not adsorbed in the dynamic adsorption experiment. These results suggest that the chimeric AQP4 coupled immunosorbent can provide a new approach for specific immunoadsorption (IA) treatment of NMOSD.

Pre-transplant donor specific antibodies in ABO incompatible kidney transplantation - data from the Swiss transplant cohort study

Background

Living donor (LD) kidney transplantation in the setting of ABO blood group incompatibility (ABOi) has been previously reported to be associated with increased risk for antibody-mediated rejection (ABMR). It is however unclear if the presence of pre-transplant donor specific antibodies (DSA) works as an additive risk factor in the setting of ABOi and if DSA positive ABOi transplants have a significantly worse long-term outcome as compared with ABO compatible (ABOc) DSA positive transplants.

Methods

We investigated the effect of pre-transplant DSA in the ABOi and ABOc setting on the risk of antibody-mediated rejection (ABMR) and graft loss in a cohort of 952 LD kidney transplants.

Results

We found a higher incidence of ABMR in ABOi transplants as compared to ABOc transplants but this did not significantly affect graft survival or overall survival which was similar in both groups. The presence of pre-transplant DSA was associated with a significantly increased risk of ABMR and graft loss both in the ABOi and ABOc setting. We could not detect an additional risk of DSA in the ABOi setting and outcomes were comparable between DSA positive ABOi and ABOc recipients. Furthermore, a combination of DSA directed at both Class I and Class II, as well as DSA with a high mean fluorescence intensity (MFI) showed the strongest relation to ABMR development and graft loss.

Conclusion

The presence of pre-transplant DSA was associated with a significantly worse long-term outcome in both ABOi and ABOc LD kidney transplants and our results suggests that the risk associated with pre-transplant DSA is perhaps not augmented in the ABOi setting. Our study is the first to investigate the long-term effects of DSA in the ABOi setting and argues that pre-transplant DSA risk could potentially be evaluated similarly regardless of ABO compatibility status.

Large volume plasmapheresis using a single-use immunoadsorption column: A cost-effective approach for desensitization in ABO-incompatible liver transplant

INTRODUCTION

Liver transplant is a life-saving treatment, but due to the limited availability of suitable liver donors, ABO-incompatible liver transplants (ABOi-LT) are conducted to increase the availability of liver donors. Perioperative desensitization for ABOi-LT is an established strategy to circumvent the risk of graft rejection. A single prolonged session can be performed to achieve the desired titers to avoid using multiple immunoadsorption (IA) columns or off-label reuse of single-use columns. This study retrospectively assessed the effectiveness of a single prolonged plasmapheresis session using IA as a desensitization strategy in live donor liver transplant (LDLT).

MATERIALS AND METHODS

This retrospective observational study conducted at a center for liver diseases in North India on six ABOi-LDLT patients who underwent single prolonged IA sessions in the perioperative period from January 2018 to June 2021.

RESULTS

Median baseline titer in patients was 320 (64, 1024). The median plasma volume adsorbed was 7.5 volumes (4, 8) per procedure, with a mean procedure time of 600 min (310-753). The reduction in titer ranged from 4 log to 7 log reduction per procedure. Two patients developed transient hypotension during the procedure, which was managed successfully. The median duration of pre-transplant hospital stay was 1.5 days (1, 3).

CONCLUSION

Desensitization therapy helps overcome the ABO barrier and decreases the waiting period before a transplant when ABO identical donors are unavailable. A single prolonged IA session reduces the cost of additional IA columns and hospital stay, thus making it a cost-effective approach to desensitization.

Randomized Trial to Assess the Clinical Utility of Renal Allograft Monitoring by Urine CXCL10 Chemokine

SIGNIFICANCE STATEMENT

This study is the first randomized controlled trial to investigate the clinical utility of a noninvasive monitoring biomarker in renal transplantation. Although urine CXCL10 monitoring could not demonstrate a beneficial effect on 1-year outcomes, the study is a rich source for future design of trials aiming to explore the clinical utility of noninvasive biomarkers. In addition, the study supports the use of urine CXCL10 to assess the inflammatory status of the renal allograft.

BACKGROUND

Urine CXCL10 is a promising noninvasive biomarker for detection of renal allograft rejection. The aim of this study was to investigate the clinical utility of renal allograft monitoring by urine CXCL10 in a randomized trial.

METHODS

We stratified 241 patients, 120 into an intervention and 121 into a control arm. In both arms, urine CXCL10 levels were monitored at three specific time points (1, 3, and 6 months post-transplant). In the intervention arm, elevated values triggered performance of an allograft biopsy with therapeutic adaptations according to the result. In the control arm, urine CXCL10 was measured, but the results concealed. The primary outcome was a combined end point at 1-year post-transplant (death-censored graft loss, clinical rejection between month 1 and 1-year, acute rejection in 1-year surveillance biopsy, chronic active T-cell-mediated rejection in 1-year surveillance biopsy, development of de novo donor-specific HLA antibodies, or eGFR <25 ml/min).

RESULTS

The incidence of the primary outcome was not different between the intervention and the control arm (51% versus 49%; relative risk (RR), 1.04 [95% confidence interval, 0.81 to 1.34]; P = 0.80). When including 175 of 241 (73%) patients in a per-protocol analysis, the incidence of the primary outcome was also not different (55% versus 49%; RR, 1.11 [95% confidence interval, 0.84 to 1.47]; P = 0.54). The incidence of the individual end points was not different as well.

CONCLUSIONS

This study could not demonstrate a beneficial effect of urine CXCL10 monitoring on 1-year outcomes (ClinicalTrials.gov_ NCT03140514 ).

Current Perspectives in ABO-Incompatible Kidney Transplant

For a long time, ABO incompatible living donor kidney transplantation has been considered contraindicated, due to the presence of isohemagglutinins, natural antibodies reacting with non-self ABO antigens. However, as the demand for kidney transplantation is constantly growing, methods to expand the donor pool have become increasingly important. Thus, in the last decades, specific desensitization strategies for ABOi transplantation have been developed. Nowadays, these regimens consist of transient removal of preformed anti-A or anti-B antibodies by using plasmapheresis or immunoadsorption and B-cell immunity modulation by CD20+ cells depletion with rituximab, in association with maintenance immunosuppression including corticosteroids, tacrolimus and mycophenolate mofetil. The outcome in ABOi kidney transplantation have markedly improved over the years. In fact, although randomized trials are still lacking, recent meta analysis has revealed that there is no difference in terms of graft and patient's survival between ABOi and ABO compatible kidney transplant, even in the long term. However, many concerns still exist, because ABOi kidney transplantation is associated with an increased risk of bleeding and infectious complications, partly related to the effects of extracorporeal treatments and the strong immunosuppression. Thus, a continuous improvement in desensitization strategies, with the aim of minimize the immunosuppressive burden, on the basis of immune pathogenesis, antibodies titers and/or ABO blood group, is warranted. In this review, we discuss the main immune mechanisms involved in ABOi kidney transplantation, the pathogenesis of tolerance and the desensitization regimens, including immunoadsorption and plasmapheresis and the immunosuppressive protocol. Finally, we provide an overview on outcome and future perspectives in ABOi kidney transplant.

Infection Risk in the First Year After ABO-incompatible Kidney Transplantation: A Nationwide Prospective Cohort Study

BACKGROUND

ABO-incompatible (ABOi) kidney transplantation (KT) expands the kidney donor pool and may help to overcome organ shortage. Nonetheless, concerns about infectious complications associated with ABOi-KT have been raised.

METHODS

In a nationwide cohort (Swiss Transplant Cohort Study), we compared the risk for infectious complications among ABOi and ABO-compatible (ABOc) renal transplant recipients. Infections needed to fulfill rigorous, prespecified criteria to be classified as clinically relevant. Unadjusted and adjusted competing risk regression models were used to compare the time to the first clinically relevant infection among ABOi-KT and ABOc-KT recipients. Inverse probability weighted generalized mixed-effects Poisson regression was used to estimate incidence rate ratios for infection.

RESULTS

We included 757 living-donor KT recipients (639 ABOc; 118 ABOi) and identified 717 infection episodes. The spectrum of causative pathogens and the anatomical sites affected by infections were similar between ABOi-KT and ABOc-KT recipients. There was no significant difference in time to first posttransplant infection between ABOi-KT and ABOc-KT recipients (subhazard ratio, 1.24; 95% confidence interval [CI], 0.93-1.66; P = 0.142). At 1 y, the crude infection rate was 1.11 (95% CI, 0.93-1.33) episodes per patient-year for ABOi patients and 0.94 (95% CI, 0.86-1.01) for ABOc-KT recipients. Inverse probability weighted infection rates were similar between groups (adjusted incidence rate ratio, 1.12; 95% CI, 0.83-1.52; P = 0.461).

CONCLUSIONS

The burden of infections during the first year posttransplant was high but not relevantly different in ABOi-KT and ABOc-KT recipients. Our results highlight that concerns regarding infectious complications should not affect the implementation of ABOi-KT programs.

Urinary CXCL10 Measurement in Late Renal Allograft Biopsies Predicts Outcome Even in Histologically Quiescent Patients

BACKGROUND

CXCL10 is a promising early noninvasive diagnostic marker for allograft rejection and predictive for long-term outcomes. However, its value when measured later in the posttransplant course has not yet been accurately analyzed.

METHODS

We investigated urinary CXCL10 in 141 patients from a prospective, observational renal transplant cohort with 182 clinically indicated allograft biopsies performed >12 months posttransplant and corresponding urines. Urinary CXCL10 was retrospectively quantified on stored urines using the MSD V-Plex Chemokine Panel 1 sandwich immunoassay (Meso Scale Discovery). The primary outcome was a composite of allograft loss/renal function decline (>30% estimated glomerular filtration rate [eGFR]-decrease between index biopsy and last follow-up).

RESULTS

Seventy-two patients (51%) reached the primary outcome, and their urinary CXCL10 levels were significantly higher at the time of their biopsy compared with patients with stable allograft function (median 9.3 ng/mmol vs 3.3 ng/mmol, P < .0001). Time-to-endpoint analyses according to high/low urinary CXCL10 demonstrated that low urinary CXCL10 (≤7.0 ng/mmol) was associated with 73% 5-year event-free graft survival compared with 48% with high urinary CXCL10 (>7.0 ng/mmol; P = .0001). Even in histologically quiescent patients, high urinary CXCL10 was associated with inferior endpoint-free graft survival (P = .003), and it was an independent predictor of the primary outcome (P = .03).

CONCLUSIONS

This study demonstrates that urinary CXCL10 has a promising diagnostic performance for detection of late allograft rejection and is an independent predictor of long-term renal allograft outcomes, even in histologically quiescent patients.

Short- and long-term impact of neutropenia within the first year after kidney transplantation

The aim of this retrospective single-center study was to investigate short- and long-term impact of neutropenia occurring within the first year after kidney transplantation, with a special emphasis on different neutropenia grades. In this unselected cohort, 225/721 patients (31%) developed 357 neutropenic episodes within the first year post-transplant. Based on the nadir neutrophil count, patients were grouped as neutropenia grade 2 (<1.5-1.0*10⁹ /L; n=105), grade 3 (<1.0-0.5*10⁹ /L; n=65), and grade 4 (<0.5*10⁹ /L; n=55). Most neutropenia episodes were presumably drug-related (71%) and managed by reduction/discontinuation of potentially responsible drugs (mycophenolic acid [MPA] 51%, valganciclovir 25%, trimethoprim/sulfamethoxazole 19%). Steroids were added/increased as replacement for reduced/discontinued MPA. Granulocyte colony-stimulating factor was only used in 2/357 neutropenia episodes (0.6%). One-year incidence of (sub)clinical rejection, one-year mortality as well as long-term patient and graft survival were not different among patient without neutropenia and neutropenia grade 2/3/4. However, the incidence of infections was about 3-times higher during neutropenia grade 3 and 4, but not increased during grade 2. In conclusion, neutropenia within the first year after kidney transplantation represents no increased risk for rejection and has no negative impact on long-term patient and graft survival. Adding/increasing steroids as replacement for reduced/discontinued MPA might supplement management of neutropenia.

Selective ABO immunoadsorption in hematopoietic stem cell transplantation with major ABO incompatibility

OBJECTIVE

ABO mismatch between donor and recipient occurs in 40% of allogeneic hematopoietic stem cell transplantations (HCT). Different strategies have been described to reduce isohemagglutinins (IHA) before HCT. We describe the effect of selective ABO immunoadsorption (ABO IA) on erythrocyte transfusion rate and the development of post-transplant pure red cell aplasia (ptPRCA).

METHODS

63 patients with major ABO incompatibility were retrospectively analyzed. Nine patients with major ABO incompatibility and high-IHA titer were treated by ABO IA before HCT. We analyzed the need for transfusion and the occurrence of ptPRCA. We compared the outcome with patients treated by other methods to reduce IHA.

RESULTS

In all nine patients treated by ABO IA, IHA decreased in a median four times. PtPRCA occurred in one patient. The median number of transfusions was 8 (range: 0-36) between d0 and d100. In 25 patients with high-IHA titer without treatment or treated by other methods to reduce IHA, the need for transfusions was comparable. No difference in the incidence of ptPRCA was observed.

CONCLUSIONS

Selective ABO IA is a feasible, safe, and effective method to reduce IHA before HCT in major ABO incompatibility. No effect on transfusion rate or ptPRCA compared to other strategies could be observed.

Recent progress and remaining hurdles toward clinical xenotransplantation

BACKGROUND

Xenotransplantation has made tremendous progress over the last decade.

METHODS

We discuss kidney and heart xenotransplantation, which are nearing initial clinical trials.

RESULTS

Life sustaining genetically modified kidney xenografts can now last for approximately 500 days and orthotopic heart xenografts for 200 days in non-human primates. Anti-swine specific antibody screening, preemptive desensitization protocols, complement inhibition and targeted immunosuppression are currently being adapted to xenotransplantation with the hope to achieve better control of antibody-mediated rejection (AMR) and improve xenograft longevity. These newest advances could probably facilitate future clinical trials, a significant step for the medical community, given that dialysis remains difficult for many patients and can have prohibitive costs. Performing a successful pig-to-human clinical kidney xenograft, that could last for more than a year after transplant, seems feasible but it still has significant potential hurdles to overcome. The risk/benefit balance is progressively reaching an acceptable equilibrium for future human recipients, e.g. those with a life expectancy inferior to two years. The ultimate question at this stage would be to determine if a "proof of concept" in humans is desirable, or whether further experimental/pre-clinical advances are still needed to demonstrate longer xenograft survival in non-human primates.

CONCLUSION

In this review, we discuss the most recent advances in kidney and heart xenotransplantation, with a focus on the prevention and treatment of AMR and on the recipient's selection, two aspects that will likely be the major points of discussion in the first pig organ xenotransplantation clinical trials.

Use of immunoadsorption columns in ABO-incompatible renal transplantation: A prospective study at a tertiary care center in India

Background

We present our experience of ABO-incompatible renal transplant using immunoadsorption (IA) columns. We have compared efficacy of two commercially available columns.

Methods

This single-center prospective study was conducted at Army Hospital Research and Referral, Delhi. All consecutive ABO-incompatible renal transplants from January 2014 to February 2018 were analyzed. Of 30 patients who underwent transplantations, 28 underwent antibody depletion with immunoadsorption columns. Of them, 14 cases were in the "Glycosorb group," while 14 in the "Adsopak group."

Results

The donors in the Adsopak group were older than those in the Glycosorb group (p < 0.05). Both groups had spousal donors in majority. The cutoff for the antibody titer was 1:8. The median titer in the Adsopak group was 128 (range, 1:4 to 1:2048), while that in the Glycosorb group was 24 (range, 1:8 to 1:128). All patients in the Glycosorb group had baseline titers ≤1:128, while 13 patients in the Adsopak group had baseline titers ≤1:512. Nil titer was achievable with Glycosorb® (50%,7/14) but not with Adsopak® (P < 0.01). Around 4 sessions were required for the Glycosorb group, while around 8 sessions were required for the Adsopak group before transplantation (p < 0.001). The Glycosorb group was advantageous in terms of graft failure because no rejection was noticed in these patients in their follow-up period. Three patients in the Adsopak group developed rejection (two had mixed rejection, and one had antibody-mediated rejection). Four patients died of sepsis (three in the Glycosorb and one in the Adsopak group). Lower baseline serum creatinine level was achieved in the Glycosorb group.

Conclusions

Results of ABO-incompatible renal transplantation were satisfactory, and the use of immunoadsorption columns could effectively deplete antibody titers. Glycosorb columns were more efficient than Adsopak columns. Graft survival was better with Glycosorb. Posttransplant infections were a major cause of mortality.

Tailored immunosuppression after kidney transplantation - a single center real-life experience

Background

Kidney allograft survival continuously improved with introduction of novel immunosuppressants. However, also immunologically challenging transplants (blood group incompatibility and sensitized recipients) increase. Between 2006 and 2008, a new tailored immunosuppression scheme for kidney transplantation was implemented at the University Hospital in Zurich, together with an ABO-incompatible transplant program and systematic pre- and posttransplant anti-human leukocyte antigen (HLA) antibody screening by Luminex technology. This study retrospectively evaluated the results of this tailored immunosuppression approach with a particular focus on immunologically higher risk transplants.

Methods

A total of 204 consecutive kidney transplantations were analyzed, of whom 14 were ABO-incompatible and 35 recipients were donor-specific anti-HLA antibodies (DSA) positive, but complement-dependent cytotoxicity crossmatch (CDC-XM) negative. We analyzed patient and graft survival, acute rejection rates and infectious complications in ABO-compatible versus -incompatible and in DSA positive versus negative patients and compared those with a historical control group.

Results

Overall patient, death-censored allograft survival and non-death-censored allograft survival at 4 years were 92, 91 and 87%, respectively. We found that (1) there were no differences between ABO-compatible and -incompatible and between DSA positive and DSA negative patients concerning acute rejection rate and graft survival; (2) compared with the historical control group there was a significant decrease of acute rejection rates in sensitized patients who received an induction with thymoglobulin; (3) there was no increased rate of infection among the patients who received induction with thymoglobulin compared to no induction therapy.

Conclusions

We observed excellent overall mid-term patient and graft survival rates with our tailored immunosuppression approach. Induction with thymoglobulin was efficient and safe in keeping rejection rates low in DSA positive patients with a negative CDC-XM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-020-02137-5.

Isoagglutinin removal by plasma centrifugation or filtration (single or double): A prospective study in a single center

INTRODUCTION

ABO-incompatible (ABOi) kidney transplantation, a well-established procedure, has good long-term results provided pretransplant desensitization that includes immunosuppression and apheresis.

OBJECTIVE

To compare, within the first pretransplant apheresis session given to 29 ABOi kidney-transplant candidates, the effect on isoagglutinin titers (both IgG and IgM isotypes) of three modalities: centrifugation therapeutic plasmapheresis (cTP; n = 10), filtration TP (fTP; n = 9), and double-filtration plasmapheresis (DFPP; n = 10).

RESULTS

The three groups were comparable according to baseline demographics. Treated plasma volumes were similar across the three groups, that is, 4111 ± 403 mL (cTP), 3861 ± 282 mL (fTP), and 3699 ± 820 mL (DFPP): that is, 54 ± 7, 53 ± 7, and 53 ± 10 mL/kg respectively. One session of centrifugation or filtration TP reduced IgG anti-A/anti-B isoagglutinin titer by ~4, whereas one DFPP session reduced it by ~2. One session of cTP reduced IgM anti-A isoagglutinin titer by a little less than 4, whereas fTP and DFPP sessions reduced it by ~3. There were no statistical differences across the three groups regarding isoagglutinin rebound (IgG and IgM). However, isoagglutinin IgG rebound was >4 dilutions for anti-B titers compared with ~2 dilutions for anti-A titers. The median decreases in IgG level were -3.9 g/L (DFPP), -5.9 g/L (cTP), and - 6.06 g/L (fTP) (p = ns). Median fibrinogen depletions were ~ 60% (fTP), 64% (DFPP), and 76% (cTP).

CONCLUSIONS

Isoagglutinin depletions within the first apheresis session were similar across cTP, fTP, and DFPP: this was numerically lower for DFPP.

Immunoadsorption Column Reuse

Introduction:

Selective immunoadsorption (IA) is a technique to remove preformed Anti-ABO antibodies in ABO-incompatible renal transplants (ABOiRT). Since the cost of a single IA column is high and single use rarely achieves the target anti-ABO titers, its use is not widely spread. We studied the safety and efficacy of the reuse of IA columns in ABOiRT.

Methods:

Single-center, retrospective analysis of all patients who underwent ABOiRT with IA column reuse from January 2016 to July 2018. The column was reused after sterilization with ethylene oxide and flushed with normal saline before use. Target titers (IgG) were 1:4 preoperatively. Baseline IgG titers, plasma volume processed in each session, postoperative titer rebound were recorded. The primary outcome was IgG titer reduction after each use and adverse reaction during the IA column reuse. Patients were followed up until 1 year.

Results:

16 patients underwent ABOiRT using IA columns. Baseline IgG titer ranged from 1:32 to 1:512. Reuse of IA column was done 23 times and underwent 2^nd reuse for 9 times. The average plasma volume treated was 22 L. Efficacy of the IA column in log titer reduction of anti-ABO titer was 4 logs after the first use, 3 logs after 1^st reuse, and 1.5 logs after 2^nd reuse. 12 (75%) patients successfully reached the target IgG titer of ≤1:4 solely with column reuse. One patient received a single session of plasma exchange before transplantation. Postoperatively, one patient received one session of plasma exchange due to a rebound in anti-ABO antibodies. No serious side effects were noted during the reuse.

Conclusion:

IA column reuse up to two times showed efficacy in the successful reduction of antibody titers. Column reuse was not associated with any significant side effects.

Antigen-Specific Immunoadsorption With the Glycosorb® ABO Immunoadsorption System as a Novel Treatment Modality in Pure Red Cell Aplasia Following Major and Bidirectional ABO-Incompatible Allogeneic Hematopoietic Stem Cell Transplantation

Pure red cell aplasia (PRCA) after ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT) is caused by persisting host-derived isohemagglutinins directed against donor red blood cell (RBC) antigens. ABO antigen-specific immunoadsorption (ABO-IA) with Glycosorb®, commonly used for desensitization therapy in ABO-incompatible living donor renal transplantation, specifically eliminates circulating isohemagglutinins and might represent a novel treatment option for post-HSCT PRCA. In this prospective observational (n = 3) and retrospective (n = 3) analysis of six adult HSCT-recipients with PRCA, ABO-IA was initiated at 159 (range: 104–186) days following HSCT. The median treatment frequency was 4.5 (range: 3.9–5.5) sessions/week. ABO-IA-treatment led to a continuous decrease in isohemagglutinin titers. Reticulocytes increased to ≥30 G/L after 17.5 (range: 4–37) immunoadsorption sessions over 28.5 (range: 6–49) days and continued to rise after that. By the end of the 3-month follow-up period after discontinuation of ABO-IA, all patients showed a sustained remission of PRCA and were independent of erythropoietin-stimulating agents and transfusions. No case of infection or graft-versus-host disease was observed. After a median follow-up of 22.03 (range: 6.08–149.00) months after ABO-IA-treatment, all patients were alive and showed a stable RBC engraftment of the donor blood group. Our data provide the first evidence for ABO-IA as an effective treatment for post-HSCT PRCA.

Revisiting cytomegalovirus serostatus and replication as risk factors for inferior long-term outcomes in the current era of renal transplantation

BACKGROUND

Cytomegalovirus (CMV) serostatus and CMV replication are considered as risk factors for inferior graft and patient survival after renal transplantation, but long-term outcome data are limited. The aim of this retrospective single-centre study was to investigate the impact of CMV serostatus and CMV replication/disease on long-term outcomes in a well-defined cohort managed by a standardized CMV prevention/treatment protocol.

METHODS

We investigated 599 consecutive kidney transplantations having a CMV prevention protocol consisting of either prophylaxis (D+/R- and R+ with ATG induction) or screening/deferred therapy (R+ without ATG induction). Patients were grouped according to CMV serostatus [high risk (D+/R-): n = 122; intermediate risk (R+): n = 306; low risk (D-/R-): n = 171] and occurrence of CMV replication/disease (no CMV replication: n = 419; asymptomatic CMV replication: n = 110; CMV syndrome: n = 39; tissue-invasive CMV disease: n = 31). The median follow-up time was 6.5 years.

RESULTS

Graft and patient survival were not different among the three CMV serostatus groups as well as the four CMV replication/disease groups (P ≥ 0.44). Eighty-seven patients died, 17 due to infections (21%), but none was attributable to CMV. The overall hospitalization incidence for CMV-related infection was 3% (17/599 patients). The incidence of clinical and (sub)clinical rejection was similar among the groups (P ≥ 0.17). In a multivariate Cox proportional hazard model, neither CMV serostatus, nor CMV replication, nor CMV disease were independent predictors for patient death or graft failure, respectively.

CONCLUSIONS

This retrospective single-centre study suggests that the negative impact of CMV infection on long-term patient and allograft survival as well as on allograft rejection can be largely eliminated with current diagnostic/therapeutic management.

ABO-incompatible living kidney transplantation

ABO-incompatible living kidney transplantation is nowadays a routine procedure to expand living donor pool. The past decades have seen the evolution of desensitization protocol and immunosuppression regimen. Despite increased bleeding events, infectious complications, and rejection episodes reported in some studies, favorable graft and patient survival rate are now achieved, regardless of various protocols among transplant centers. Several issues such as the usage of rituximab and standardization of blood group antibody titration remain to be settled. The deposition of C4d is no longer the histopathologic hallmark of antibody-mediated rejection, which have inspired innovative strategies of peripheral molecular screening and the improvement of histological diagnosis of AMR (antibody-mediated rejection). The better understanding of the underlying mechanism might facilitate the distinction and therapeutic schemes of AMR.

Current protocols and outcomes of ABO-incompatible kidney transplantation

One of the principal obstacles in transplantation from living donors is that approximately 30% are immunologically incompatible because of the presence in the recipient of antibodies directed against the human leukocyte antigen system of the donor or because of the incompatibility of the ABO system. The aim of this review is to describe the more recent data from the literature on the different protocols used and the clinical outcomes of ABO-incompatible kidney transplantation. Two different strategies are used to overcome these barriers: desensitization of the recipient to remove the antibodies and to prevent their rebound after transplantation and the exchange of organs between two or more pairs. The largest part of this review is dedicated to describing the techniques of desensitization. Even if the first reports of successful renal transplantation between ABO-incompatible pairs have been published by 1980, the number of ABO-incompatible transplants increased substantially in this century because of our improved knowledge of the immune system and the availability of new drugs. Rituximab has substantially replaced splenectomy. The technique of apheresis has improved and more recently a tailored desensitization proved to be the more efficient strategy avoiding an excess of immunosuppression with the related side effects. Recent reports document outcomes for such transplantation similar to the outcomes of standard transplantation.

Immunoadsorption in ABO-incompatible kidney transplantation in adult and pediatric patients with follow-up on graft and patient survival: First series from India

BACKGROUND:

There are no published reports on desensitization protocol for ABO-incompatible kidney transplants using Immuno-Adsorption (IA) plasmapheresis from India. IA offers certain advantages including processing of larger plasma volumes, quicker reduction of isoagglutinin titers and no requirement of replacement fluids.

AIMS AND OBJECTIVES:

Authors' center evaluated success of desensitization protocol, and graft/patient outcomes when IA procedures were performed for desensitization in adult and pediatric ABO-incompatible kidney transplant patients.

METHODS:

Patients undergoing ABO-incompatible kidney transplant with use of IA were evaluated at tertiary care center in north India. Patient records for 2-years were collated from hospital information system (HIS) and procedure forms.

RESULTS:

Sixteen IA procedures were performed in five patients who underwent successful ABO-incompatible kidney transplant. Initial isoagglutinin IgG titer ranged from 32-512. Mean number of IA procedures performed to achieve the desired pre-transplant IgG titer ≤8 was 3.2. New IA column was used for each patient (and re-used for the same patient, if needed, after sterilization with Low temperature steam of formaldehyde). Mean plasma volume processed during each IA procedure was 4.5 times. No adverse events were observed during any IA procedure. All patients achieved successful desensitization. All patients continue to do well clinically with mean follow-up period of 8.8 months. Although IA was expensive, it offered advantages like specificity, larger plasma volume processing with desired reduction in titer, no 'replacement fluid' requirements and no adverse events in present case series.

CONCLUSION:

IA plasmapheresis was universally successful in decreasing the ABO-isoagglutinin titers to desired level in all prospective ABO incompatible kidney transplant patients.

Reducing calcineurin inhibitor first for treating BK polyomavirus replication after kidney transplantation: long-term outcomes

BACKGROUND

Reducing immunosuppression is the mainstay of treating BK polyomavirus (BKPyV) viraemia after kidney transplantation, but the best approach, efficacy and impact are undefined. We established a standard operating procedure (SOP) treating BKPyV viraemia based on first reducing calcineurin inhibitor ('CNI first'). The aim of this study was to investigate long-term outcomes in 644 consecutive transplantations using this SOP.

METHODS

Patients were monitored for active BKPyV infection by urinary decoy cells and, if positive, by BKPyV viraemia. In case of sustained BKPyV viraemia >1000 copies/mL, immunosuppression was reduced stepwise according to the SOP. Patients were classified as 'no decoy cells' [n = 432 (66%)], 'decoy cells/no viraemia' [n = 107 (17%)] and 'viraemia' [n = 105 (17%)].

RESULTS

At 6-years post-transplant, graft survival was ∼84%, the clinical rejection rate was ∼25% and they were not different among the three groups (P = 0.14; P = 0.91). The median estimated glomerular filtration rate at the last follow-up was similar (range 49-53 mL/min, P = 0.08). Of 105 viraemic patients, 101 (96%) cleared BKPyV viraemia. In 39% of patients, viraemia clearance followed a tacrolimus reduction. A reduction of mycophenolic acid was required in 43% and discontinuation in 3%. No short-term graft loss was directly attributable to BKPyV-associated nephropathy. After a median follow-up of 5 years after clearance of BKPyV viraemia, 11/101 patients (11%) developed clinical rejection: 7 (7%) T-cell-mediated rejection and 4 (4%) antibody-mediated rejection (ABMR).

CONCLUSIONS

Immunosuppression reduction based on 'CNI first' leads to similar long-term outcomes in patients with/without BKPyV viraemia and is associated with a low risk for ABMR after clearance of BKPyV viraemia. Randomized trials are needed to compare the risks and benefits of immunosuppression reduction strategies in kidney transplant patients with BKPyV viraemia.

Therapeutic Immunoadsorption and Conventional Plasma Exchange in ABO-incompatible Renal Transplant: An Exculpatory Evidence

Aim

The objective of this study was to compare the efficacy of immunoadsorption (IA) with conventional therapeutic plasma-exchange (cTPE) in ABO-incompatible (ABOi) renal transplant.

Methods

Data of patients from July 2015 to June 2017 (category-I, number of patients (N) = 11; IA±cTPE) on the average length of stay (ALOS), number of cTPE/IA, antibody-titers (AT), creatinine, patient and graft survival at one year were compared retrospectively with patients in period from February 2012 to June 2015 (category-II, N = 29; cTPE only). AT of patients not decreasing to less than one fold after two cTPE were shifted for IA. For patients undergoing IA, real-time AT was done and IA stopped after target titer (TT <1:8) was achieved. Post-transplant cTPE was done if, titers rebounded to ≥1:8. Intravenous immunoglobulin (IVIG) was given after every cTPE/IA. Cost comparisons were made.

Results

In category-I, seven patients (63.63%) were shifted to IA from cTPE. The mean cTPE procedures in category I and II are 3.5 ± 2.4 and 4.8 ± 2.5, respectively (p = 0.206). The mean IA procedures in category-I are 1.6 ± 0.5. The number of patients requiring post-operative TPE was less in category-I than category-II, i.e., N = 5, 45.5% vs N = 20, 69%, respectively (p = 0.171). The expense of IA in category-I vs cTPE in category-II was statistically not significant (p = 0.422) but had significant lesser ALOS (p = 0.044). Expenses, when a patient undergoes both cTPE and IA (category-I), are significantly higher to category-II (p = 0.003). The two groups were comparable in AT, creatinine value, graft and patient survival rates at one year.

Conclusion

Contrary to the general judgment of IA being expensive than cTPE, this study shows equivalent expenditures with comparable therapeutic outcomes.

Pediatric ABO-incompatible kidney transplantation: Evolving with the advancing apheresis technology: A single-center experience

Recent literature has endorsed favorable outcomes following ABOi kidney transplantation in pediatric population. Nevertheless, reluctance to pursue an ABOi still remains pervasive. This could be ascribed to various legitimate reasons, namely less extensive pediatric ABOi data, technical difficulties encountered during PP, cost restraints, and concerns regarding higher rates of antibody-mediated rejection, infectious complications, and post-transplant lymphoproliferative disorder as compared to adults. However, given the similar excellent outcomes of both ABOi and ABOc kidney transplantation, clinicians should consider this option sooner if a compatible donor or swap is not available. Here, we describe the outcomes of three pediatric ABOi performed at our institute in India (from 2014 till now), wherein distinct apheresis modalities had been employed in each desensitization protocol, and our techniques evolved with advancing science in apheresis. This case series includes India's first published pediatric ABO-incompatible transplant (Case 2) and the youngest child to undergo ABO-incompatible renal transplant in SAARC nations (Case 3).

Donor-specific antibodies and antibody-mediated rejection in vascularized composite allotransplantation

PURPOSE OF REVIEW

The presence of donor-specific antibodies (DSA) increases the risk of graft failure. Although DSA characteristics, human leukocyte antigen class specificity, mean fluorescence intensity and immunoglobulin G subclasses, and their impact on the graft are quite well studied in solid organ transplants, very little information is known about their impact on vascularized composite allotransplantation (VCA). The aim of this review is to highlight recent publications regarding occurrence and effects of DSA, their follow-up and treatment in the field of VCA.

RECENT FINDINGS

The latest publications dealing with antibody-mediated rejection in VCA are mainly case presentations and reports embedded in reviews. The most important findings shown were the demonstration of the severe clinical impact of de-novo DSA and the urgent need of finding a therapeutic strategy for patients with acute antibody-mediated rejection. Suggested protocols for desensitization of possible candidates for reconstructive transplantation have been published, as these individuals are often highly sensitized and not appropriate patients for a standard surgical procedure because of their major tissue defects.

SUMMARY

The functional outcome of reconstructive transplantation has clearly exceeded the results achieved with conventional surgical techniques. The recipients' immune response, particularly development of DSA and the long-term adherence, which is probably associated with the occurrence of chronic rejection, remain a challenge.

Treatment of large plasma volumes using specific immunoadsorption to desensitize ABO-incompatible kidney-transplant candidates

Background

ABO-incompatible (ABOi) kidney-transplantation has very good long-term results, i.e. similar to those observed for living-kidney ABO-compatible transplantation. This is because patients are desensitized at pretransplant using apheresis and rituximab therapy, with tacrolimus-based immunosuppression.

Objectives

To assess the efficacy of a single, pretransplant (Day –1), specific immunoadsorption session using Glycosorb® columns (anti-A or anti-B; Glycorex Sweden) to treat large volumes of plasma (up to 18 L).

Patients and Methods

Prospective single-center study evaluating 12 consecutive patients (6 males), aged 40 (23–59) years. Incompatibilities were A into 0 (8), B into 0 (3), and AB into 0 (1). Pretransplant desensitization relied on rituximab (D–30), tacrolimus, mycophenolic acid, and steroids (all started on D–13), and a single session of specific immunoadsorption on D–1. Immunoadsorption was coupled in tandem with a hemodialysis session.

Results

Overall, 15 L (11–18) of plasma were treated per patient, i.e., 0.2 (0.11–0.36 L/kg). Isoagglutinin titers were 1/16 (1/5–1/64) before the procedure, decreasing after 6 hours to 1/5 (1/1–1/16 P = 0.008), and to 1/2 (1/1–1/8; P = 0.05) at completion of the session. The next day, i.e., the day of transplantation, there was no rebound of isoagglutinins [1/4 (1/1–1/5); P = ns]. The procedure was well tolerated with no side-effects and no significant changes in hemoglobin level, platelet counts, fibrinogen, or albumin levels.

Conclusions

For ABOi kidney-transplantation, a single, longer, specific immunoadsorption session was very efficient at 1-day pre-transplantation with no rebound. These results should be confirmed when isoagglutinin titers are higher (≥120).

Strategies to overcome the ABO barrier in kidney transplantation

Kidney transplantation across the ABO blood group barrier was long considered a contraindication for transplantation, but in an effort to increase donor pools, specific regimens for ABO-incompatible (ABOi) transplantation have been developed. These regimens are now widely used as an integral part of the available treatment options. Various desensitization protocols, commonly based on transient depletion of preformed anti-A and/or anti-B antibodies and modulation of B-cell immunity, enable excellent transplant outcomes, even in the long-term. Nevertheless, the molecular mechanisms behind transplant acceptance facilitated by a short course of anti-humoral treatment are still incompletely understood. With the evolution of efficient clinical programmes, tailoring of recipient preconditioning based on individual donor-recipient blood type combinations and the levels of pretransplant anti-A/B antibodies has become possible. In the context of low antibody titres and/or donor A2 phenotype, immunomodulation and/or apheresis might be dispensable. A concern still exists, however, that ABOi kidney transplantation is associated with an increased risk of surgical and infectious complications, partly owing to the effects of extracorporeal treatment and intensified immunosuppression. Nevertheless, a continuous improvement in desensitization strategies, with the aim of minimizing the immunosuppressive burden, might pave the way to clinical outcomes that are comparable to those achieved in ABO-compatible transplantation.

Antigen-Specific versus Non-Antigen-Specific Immunoadsorption in ABO-Incompatible Renal Transplantation

Introduction

ABO-incompatible (ABOi) renal transplantation (RTx) from living donors is an established procedure to expand the donor pool for patients with end stage renal disease. Immunoadsorption (IA) is a standard procedure for the removal of preformed antibodies against the allograft. In this study, antigen-specific and non-antigen-specific IA in ABOi RTx were compared.

Patients and Methods

10 patients underwent antigen-specific IA (Glycosorb group) and 13 patients non-antigen-specific IA (Immunosorba group). The effects of both procedures regarding antibody reduction, number of treatments, complications, costs, as well as the allograft function and patient survival were compared between both groups.

Results

Although the IgG levels were reduced equally by both procedures (p=0.82), the reduction of the IgM level was more effective in the Glycosorb group (p=0.0172). Patients in both groups required a median number of 6 IA before ABOi RTx. Allograft function at one year after AB0i RTx was similar in both groups (estimated glomerular filtration rate: 66 vs. 64 ml/min/1.73m² respectively), with a death-censored graft survival of 90.0% and 92.3% respectively. Complication rates did not differ between procedures. Due to the reuse of non-antigen-specific Immunosorba columns, costs were considerably lower in this group; however, the use of the Immunosorba-based IA was less time-efficient.

Conclusion

Considering upcoming alternatives as simultaneous performance of dialysis and IA or a possible reuse of Glycosorb columns, this might become less relevant in the future.