Novel Therapeutic Approaches to Allosensitization and Antibody-mediated Rejection

Oxidized ATP Suppresses B Lymphocyte Activity to Attenuate Antibody-mediated Rejection of Kidney Allografts in Mice

BACKGROUND

Antibody-mediated rejection (AMR) is a major cause of renal allograft dysfunction and loss. Targeting B cells and/or donor-specific antibody removal using plasma exchange and anti-CD20 antibodies are increasingly used in clinical practice, but the efficacy remains limited. Recent studies suggest that targeting purinergic P2X7 receptor/ATP axis can have profound immune regulatory effects in transplant models, but the mechanisms involved remain incompletely defined.

METHODS

Purified B cells were isolated from the spleen of Balb/C mice and cultured with oxidized ATP at different concentrations. Proliferation and differentiation of B cells were examined. Effects of oxidized ATP were examined in a presensitized animal model where kidney allograft rejection mimics aspects of clinical AMR. Histopathology was assessed at the time of rejection or on day 5 after kidney transplantation. Infiltrating immune cells in renal allografts were detected by flow cytometry.

RESULTS

Oxidized ATP inhibited B-cell activation and proliferation in vitro, significantly attenuated histological signs of graft injury and prolonged kidney allograft survival. Mechanistically, oxidized ATP inhibited antibody secretion by activated B cells in response to lipopolysaccharide stimulation and markedly suppressed the production of donor-specific antibody in kidney allograft recipients. Oxidized ATP also reduced graft infiltration by other inflammatory cells.

CONCLUSIONS

These findings provide evidence for the involvement of the purinergic P2X7 receptor pathway in AMR and suggest that targeting this pathways may have important clinical implications.

Desensitization of Highly Immunized Kidney Transplant Recipients Awaiting Transplantation-Polish Single-Center Experience

INTRODUCTION

The increasing number of highly immunized patients waiting for kidney transplantation is a significant problem in Europe as the proportion of such patients has doubled in the last decade. Transplantation in this group is enabled by desensitization methods, i.e., intravenous pharmacotherapy with human immunoglobulin (IVIG), anti-CD20 monoclonal antibody (rituximab), and plasma exchange. The objective was to evaluate the efficacy and safety of this protocol.

MATERIAL AND METHODS

The inclusion criteria: presence of established anti-HLA antibodies with complement-binding capacity, i.e., anti-HLAC1q+ (>MFI 15,000 for the most common antigens), no renal transplantation within 1 year after activation on the waiting list. Thirteen patients were selected for the procedure. IVIG was administered twice (2 g/kg-maximum 140 g/dose). Between IVIG doses, patients received rituximab (375 mg/m2). Anti-HLA was tested after 1 and 2 months after completion of the procedure.

RESULTS

All patients have completed the protocol. No significant changes after desensitization in the amount/profile of alloantibodies were observed. However, with negative vCM for HLA-A/B/DR (no DSA against the reported donor) and negative CM-CDC, according to the allocation system, patients were given priority on the recipient list. Seven out of 13 patients received a transplant within 12 months after treatment (mean 11.5 weeks). Renal graft function was good (mean creatinine level after 1 month: 1.5 mg/dL). No incidents of acute rejection were reported. The most common complications were infections (especially pneumonia).

CONCLUSION

The desensitization protocol (IVIG + rituximab) allows highly immunized patients to undergo organ transplantation. In short-term analysis, no acute rejection was observed, graft function was satisfactory. Desensitization was associated with an increased risk of infection.

Relationship between the microenvironment and survival in kidney transplantation: a bibliometric analysis from 2013 to 2023

Background

Kidney transplantation is considered the most effective treatment for end-stage renal failure. Recent studies have shown that the significance of the immune microenvironment after kidney transplantation in determining prognosis of patients. Therefore, this study aimed to conduct a bibliometric analysis to provide an overview of the knowledge structure and research trends regarding the immune microenvironment and survival in kidney transplantation.

Methods

Our search included relevant publications from 2013 to 2023 retrieved from the Web of Science core repository and finally included 865 articles. To perform the bibliometric analysis, we utilized tools such as VOSviewer, CiteSpace, and the R package "bibliometrix". The analysis focused on various aspects, including country, author, year, topic, reference, and keyword clustering.

Results

Based on the inclusion criteria, a total of 865 articles were found, with a trend of steady increase. China and the United States were the countries with the most publications. Nanjing Medical University was the most productive institution. High-frequency keywords were clustered into 6 areas, including kidney transplantation, transforming growth factor β, macrophage, antibody-mediated rejection, necrosis factor alpha, and dysfunction. Antibody mediated rejection (2019-2023) was the main area of research in recent years.

Conclusion

This groundbreaking bibliometric study comprehensively summarizes the research trends and advances related to the immune microenvironment and survival after kidney transplantation. It identifies recent frontiers of research and highlights promising directions for future studies, potentially offering fresh perspectives to scholars in the field.

Screening and Management of PTLD

Posttransplant lymphoproliferative disorder (PTLD) represents a heterogeneous group of lymphoproliferative diseases occurring in the setting of immunosuppression following hematopoietic stem cells transplant and solid organ transplantation. Despite its overall low incidence, PTLD is a serious complication following transplantation, with a mortality rate as high as 50% in transplant recipients. Therefore, it is important to establish for each transplant recipient a personalized risk evaluation for the development of PTLD based on the determination of Epstein-Barr virus serostatus and viral load following the initiation of immunosuppression. Due to the dynamic progression of PTLD, reflected in the diverse pathological features, different therapeutic approaches have been used to treat this disorder. Moreover, new therapeutic strategies based on the administration of virus-specific cytotoxic T cells have been developed. In this review, we summarize the available data on screening and treatment to suggest a strategy to identify transplant recipients at a higher risk for PTLD development and to review the current therapeutic options for PTLD.

Memory T follicular helper cells drive donor-specific antibodies independent of memory B cells and primary germinal center and alloantibody formation

Human leukocyte antigen antibodies are important immunologic mediators of renal allograft loss and are difficult to control. The inability to permanently eliminate donor-specific antibodies (DSA) is partly due to an incomplete understanding of the cellular mechanisms driving alloantibody formation, recurrence, and maintenance. Memory T follicular helper (mTfh) cells rapidly interact with memory B cells upon antigen re-exposure for anamnestic humoral responses, but little is known about Tfh memory in transplantation. We hypothesized that alloreactive mTfh cells form after transplantation and play a critical role in DSA formation following alloantigen re-encounter. To test this hypothesis, we utilized murine skin allograft models to identify and characterize Tfh memory and interrogate its ability to mediate alloantibody responses. We identified alloreactive Tfh memory as a mediator of accelerated humoral alloresponses independent of memory B cells and primary germinal center, or DSA, formation. Furthermore, we demonstrate that mTfh-driven alloantibody formation is susceptible to CD28 costimulation blockade. These findings provide novel insight into a pathologic role for memory Tfh in alloantibody responses and strongly support shifting therapeutic focus from the singular targeting of B cell lineage cells and alloantibodies themselves to multimodal strategies that include inhibition of mTfh cells to treat DSA.

Antibody-mediated rejection in xenotransplantation: Can it be prevented or reversed?

Antibody-mediated rejection (AMR) is the commonest cause of failure of a pig graft after transplantation into an immunosuppressed nonhuman primate (NHP). The incidence of AMR compared to acute cellular rejection is much higher in xenotransplantation (46% vs. 7%) than in allotransplantation (3% vs. 63%) in NHPs. Although AMR in an allograft can often be reversed, to our knowledge there is no report of its successful reversal in a pig xenograft. As there is less experience in preventing or reversing AMR in models of xenotransplantation, the results of studies in patients with allografts provide more information. These include (i) depletion or neutralization of serum anti-donor antibodies, (ii) inhibition of complement activation, (iii) therapies targeting B or plasma cells, and (iv) anti-inflammatory therapy. Depletion or neutralization of anti-pig antibody, for example, by plasmapheresis, is effective in depleting antibodies, but they recover within days. IgG-degrading enzymes do not deplete IgM. Despite the expression of human complement-regulatory proteins on the pig graft, inhibition of systemic complement activation may be necessary, particularly if AMR is to be reversed. Potential therapies include (i) inhibition of complement activation (e.g., by IVIg, C1 INH, or an anti-C5 antibody), but some complement inhibitors are not effective in NHPs, for example, eculizumab. Possible B cell-targeted therapies include (i) B cell depletion, (ii) plasma cell depletion, (iii) modulation of B cell activation, and (iv) enhancing the generation of regulatory B and/or T cells. Among anti-inflammatory agents, anti-IL6R mAb and TNF blockers are increasingly being tested in xenotransplantation models, but with no definitive evidence that they reverse AMR. Increasing attention should be directed toward testing combinations of the above therapies. We suggest that treatment with a systemic complement inhibitor is likely to be most effective, possibly combined with anti-inflammatory agents (if these are not already being administered). Ultimately, it may require further genetic engineering of the organ-source pig to resolve the problem entirely, for example, knockout or knockdown of SLA, and/or expression of PD-L1, HLA E, and/or HLA-G.

Antibody-Mediated Rejection: Diagnosis and Treatment

Antibody-mediated rejection (AMR) is a form of lung allograft rejection that is emerging as an important risk factor for chronic lung allograft dysfunction and decreased long-term survival. In this review, we provide a brief overview of our current understanding of its pathophysiology with an emphasis on donor-specific antibodies before moving on to focus on the current diagnostic criteria and treatment strategies. Our goal is to discuss the limitations of our current knowledge and explore how novel diagnostic and therapeutic options aim to improve outcomes through earlier definitive diagnosis and preemptive targeted treatment.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Predictive Potential of Flow Cytometry Crossmatching in Deceased Donor Kidney Transplant Recipients Subjected to Peritransplant Desensitization

Recipient sensitization is a major risk factor of antibody-mediated rejection (ABMR) and inferior graft survival. The predictive effect of solid-phase human leukocyte antigen antibody testing and flow cytometry crossmatch (FCXM) in the era of peritransplant desensitization remains poorly understood. This observational retrospective single-center study with 108 donor-specific antibody (DSA)-positive deceased donor kidney allograft recipients who had undergone peritransplant desensitization aimed to analyze variables affecting graft outcome. ABMR rates were highest among patients with positive pretransplant FCXM vs. FCXM-negative (76 vs. 18.7%, p < 0.001) and with donor-specific antibody mean fluorescence intensity (DSA MFI) > 5,000 vs. <5,000 (54.5 vs. 28%, p = 0.01) despite desensitization. In univariable Cox regression, FCXM positivity, retransplantation, recipient gender, immunodominant DSA MFI, DSA number, and peak panel reactive antibodies were found to be associated with ABMR occurrence. In multivariable Cox regression adjusted for desensitization treatment (AUC = 0.810), only FCXM positivity (HR = 4.6, p = 0.001) and DSA number (HR = 1.47, p = 0.039) remained significant. In conclusion, our data suggest that pretransplant FCXM and DSA number, but not DSA MFI, are independent predictors of ABMR in patients who received peritransplant desensitization.

Transplantation and immunosuppression: a review of novel transplant-related immunosuppressant drugs

Immunosuppressive drugs used in the transplantation period are generally defined as induction and maintenance therapy. The use of immunosuppressants, which are particularly useful and have fewer side effects, decreased both mortality and morbidity. Many drugs such as steroids, calcineurin inhibitors (cyclosporine-A, tacrolimus), antimetabolites (mycophenolate mofetil, azathioprine), and mTOR inhibitors (sirolimus, everolimus) are used as immunosuppressive agents. Although immunosuppressant drugs cause many side effects such as hypertension, infection, and hyperlipidemia, they are the agents that should be used to prevent organ rejection. This shows the importance of individualized drug use. The optimal immunosuppressive therapy post-transplant is not established. Therefore, discovering less toxic but more potent new agents is of great importance, and new experimental and clinical studies are needed in this regard.Our review discussed the mechanism of immunosuppressants, new agents' discovery, and current therapeutic protocols in the transplantation.

Obinutuzumab in Kidney Transplantation: Effect on B-cell Counts and Crossmatch Tests

BACKGROUND

Resistance to the action of rituximab (RTX) has been documented in several diseases. More recently, obinutuzumab (OBZ) has shown promise where RTX has failed in oncology and lupus nephritis. Unlike RTX, OBZ is a weak activator of complement, which may avoid the false-positive complement-dependent cytotoxicity (CDC) crossmatch tests after RTX infusions.

METHODS

The aim of this study was to explore the effect of OBZ on B-cell depletion in kidney-transplant candidates and its impact on crossmatch test results. We included 12 patients: who were either highly sensitized kidney-transplant candidates or kidney-transplant recipients presenting with antibody-mediated rejection. Six received OBZ and 6 received RTX. CD-19 counts, flow cytometry and CDC crossmatch tests were run immediately before and at 2 weeks after drug infusion.

RESULTS

OBZ reduced CD-19 counts: median reduction was 98%. B-cell CDC crossmatch test results became positive following RTX infusion but were not affected by OBZ infusion.

CONCLUSIONS

OBZ effectively depleted B-cell counts in sensitized kidney-transplant candidates and, unlike RTX, had no effect on CDC crossmatch results.

CD38 Antibody Daratumumab for the Treatment of Chronic Active Antibody-mediated Kidney Allograft Rejection

BACKGROUND

Late antibody-mediated rejection (AMR) is a major cause of transplant failure. Potential therapeutic targets are plasma cells and natural killer (NK) cells, both expressing high levels of CD38.

METHODS

Here, we report the use of CD38 monoclonal antibody daratumumab (9-mo course) in a kidney allograft recipient diagnosed with smoldering myeloma and anti-HLA class II donor-specific antibody-positive chronic active AMR 13 years after transplantation. Patient monitoring included serial HLA single-antigen testing, peripheral blood immune cell phenotyping, as well as follow-up allograft and bone marrow biopsies at 3 and 9 months, including analyses of rejection-related gene expression patterns.

RESULTS

Daratumumab led to persistent CD138+ cell depletion in the bone marrow and blood and substantially decreased NK cells counts in blood and graft tissue. At the same time, donor-specific antibody in serum disappeared, and in vitro alloantibody production by CD138+ cells enriched from bone marrow aspirates was abrogated. A 3-month follow-up biopsy revealed a complete resolution of microcirculation inflammation (g+ptc: 3 to 0) and molecular AMR activity (AMR score: 0.79 to <0.2). The same biopsy showed (subclinical) tubulointerstitial inflammation, which prompted steroid treatment. Over an observation period of 12 months, graft function stabilized.

CONCLUSIONS

Targeting CD38 for plasma cell and NK cell depletion may be an effective strategy to counteract AMR. Our results may encourage the design of future trials to clarify the role of this innovative treatment concept in organ transplantation.

Superior inhibition of alloantibody responses with selective CD28 blockade is CTLA-4 dependent and T follicular helper cell specific

Anti-donor antibodies cause immunologic injury in transplantation. CD28 blockade with CTLA-4-Ig has the ability to reduce the incidence of these donor-specific antibodies (DSA), but its mechanism is suboptimal for the inhibition of alloimmunity in that CTLA-4-Ig blocks both CD28 costimulation and CTLA-4 coinhibition. Thus selective CD28 blockade that spares CTLA-4 has potential to result in improved inhibition of humoral alloimmunity. To test this possibility, we utilized a full allogeneic mismatch murine transplant model and T follicular helper (Tfh):B cell co-culture system. We observed that selective blockade with an anti-CD28 domain antibody (dAb) compared to CTLA-4-Ig led to superior inhibition of Tfh cell, germinal center, and DSA responses in vivo and better control of B cell responses in vitro. CTLA-4 blockade enhanced the humoral alloresponse and, in combination with anti-CD28 dAb, abrogated the effects of selective blockade. This CTLA-4-dependent inhibition was Tfh cell specific in that CTLA-4 expression by Tfh cells was necessary and sufficient for the improved humoral inhibition observed with selective CD28 blockade. As CD28 blockade attracts interest for control of alloantibodies in the clinic, these data support selective CD28 blockade as a superior strategy to address DSA via the sparing of CTLA-4 and more potent targeting of Tfh cells.

Immunosuppression trends in solid organ transplantation: The future of individualization, monitoring, and management

Immunosuppression regimens used in solid organ transplant have evolved significantly over the past 70 years in the United States. Early immunosuppression and targets for allograft success were measured by incidence and severity of allograft rejection and 1-year patient survival. The limited number of agents, infancy of human leukocyte antigen (HLA) matching techniques and lack of understanding of immunoreactivity limited the early development of effective regimens. The 1980s and 1990s saw incredible advancements in these areas, with acute rejection rates halving in a short span of time. However, the constant struggle to achieve the optimal balance between under- and overimmunosuppression is weaved throughout the history of transplant immunosuppression. The aim of this paper is to discuss the different eras of immunosuppression and highlight the important milestones that were achieved while also discussing this in the context of rational agent selection and regimen design. This discussion sets the stage for how we can achieve optimal long-term outcomes during the next era of immunosuppression, which will move from universal protocols to patient-specific optimization.

Antibody-medicated rejection after heart transplantation: diagnosis and clinical implications

PURPOSE OF REVIEW

The present article will review the diagnosis of antibody-mediated rejection in heart transplant recipients and further explore the clinical implications.

RECENT FINDINGS

Improved diagnostic techniques have led to increased recognition of antibody-mediated rejection and better understanding of the long-term consequences in heart transplant recipients. Endomyocardial biopsy remains the gold standard for the diagnosis of antibody-medicated ejection; however, several advances in molecular testing have emerged, including the use of gene expression profiling, messenger RNA, and microRNA. Routine surveillance of donor-specific antibodies identifies recipients at high risk for graft compromise. Additionally, new monoclonal antibody therapies have broadened our repertoire in the treatment of rejection.

SUMMARY

Advances in molecular testing for antibody-mediated rejection may improve the associated long-term complication, while minimizing risk to the patient.

Anti-BAFF Treatment Interferes With Humoral Responses in a Model of Renal Transplantation in Rats

BACKGROUND

B-cell-activating factor (BAFF) is associated with donor-specific antibodies (DSA) and poorer outcomes after renal transplantation (RTx). We examined the effects of anti-BAFF treatment on B cells, expression of costimulatory molecules and cytokines, germinal centers (GCs), and DSA formation in an RTx model in rats.

METHODS

Anti-BAFF antibody was injected on days 3, 17, 31, and 45 after allogeneic RTx. Rats received reduced dose cyclosporine A for 28 or 56 days to allow chronic rejection and DSA formation. Leukocytes, B-cell subsets, and DSA were measured using flow cytometry; expression of cytokines and costimulatory molecules was measured by quantitative polymerase chain reaction, and GCs and T follicular helper were assessed using immunohistochemistry. Rejection was evaluated by a nephropathologist.

RESULTS

Anti-BAFF treatment reduced the frequency of B cells in allografts and spleen. Naive B cells were strongly reduced by anti-BAFF treatment in all compartments. Messenger RNA expression of interleukin-6 and the costimulatory molecules CD40 and inducible T cell costimulator ligand was significantly reduced in anti-BAFF-treated rats. GC area was smaller and plasmablasts/plasma cell numbers lower in anti-BAFF-treated rats, which was reflected by less DSA in certain IgG subclasses.

CONCLUSIONS

Anti-BAFF treatment interferes with humoral responses at multiple levels in this model of allogeneic RTx.

Novel therapeutic opportunities afforded by plasma cell biology in transplantation

Despite new immunotherapies aimed at B and T cells, plasma cells and their lifelong antibody secretion constitute a major immune barrier to long-term graft survival. In this mini-review, we survey the recent advances that have been made in the biology and immunometabolism of long-lived plasma cells, and outline aspects of plasma cell function that can be exploited for clinical benefit in recipients of solid organ transplants. A handful of ongoing studies are already targeting plasma cells to achieve desensitization and reduce the alloantibody burden in individuals posttransplant. In reviewing the recent strides made in our understanding of the molecular basis of plasma cell survival, we will place our discussions in the context of existing preclinical and clinical studies.

The role of novel therapeutic approaches for prevention of allosensitization and antibody-mediated rejection

Modification of pathogenic antibodies and their effector functions in autoimmune diseases or use of B cell/plasma cell-directed anticancer therapies have illuminated the biologic relevance of B cells, plasma cells (PCs), and pathogenic antibodies and complement in alloimmunity. They have also rejuvenated interest in how B cells mediate multiple effector functions that include antibody production, antigen presentation to T cells, costimulation, and the production of immune stimulating and immune modulatory cytokines that drive dysfunctional immune responses. Current methods to reduce alloantibodies are only modestly successful. Rituximab is used for desensitization and antibody-mediated rejection (AMR) treatment by targeting CD20 found on B-lymphocytes. However, PCs do not express CD20, likely explaining the limited success of this approach. Intravenous immunoglobulin and plasmapheresis (PLEX) have limited success due to antibody rebound. Despite attempts to develop tolerable therapeutics for management of AMR, none, to date, have been universally accepted or obtained Food and Drug Administration approval. Lack of approved therapeutics often results in patients having a much shorter graft survival due to AMR. Repurposing drugs from autoimmunity and cancer immunotherapy has rapidly yielded important advancements in the care of AMR patients. Here we discuss emerging therapeutics aimed at prevention and treatment of AMR.

Recent Advances and Clinical Outcomes of Kidney Transplantation

Recent advances in surgical, immunosuppressive and monitoring protocols have led to the significant improvement of overall one-year kidney allograft outcomes. Nonetheless, there has not been a significant change in long-term kidney allograft outcomes. In fact, chronic and acute antibody-mediated rejection (ABMR) and non-immunological complications following kidney transplantation, including multiple incidences of primary kidney disease, as well as complications such as cardiovascular diseases, infections, and malignancy are the major factors that have contributed to the failure of kidney allografts. The use of molecular techniques to enhance histological diagnostics and noninvasive surveillance are what the latest studies in the field of clinical kidney transplant seem to mainly focus upon. Increasingly innovative approaches are being used to discover immunosuppressive methods to overcome critical sensitization, prevent the development of anti-human leukocyte antigen (HLA) antibodies, treat chronic active ABMR, and reduce non-immunological complications following kidney transplantation, such as the recurrence of primary kidney disease and other complications, such as cardiovascular diseases, infections, and malignancy. In the present era of utilizing electronic health records (EHRs), it is strongly believed that big data and artificial intelligence will reshape the research done on kidney transplantation in the near future. In addition, the utilization of telemedicine is increasing, providing benefits such as reaching out to kidney transplant patients in remote areas and helping to make scarce healthcare resources more accessible for kidney transplantation. In this article, we discuss the recent research developments in kidney transplants that may affect long-term allografts, as well as the survival of the patient. The latest developments in living kidney donation are also explored.

Belatacept and CD28 Costimulation Blockade: Preventing and Reducing Alloantibodies over the Long Term

Purpose of Review

Highlight developments in T and B cell biology that are helping elucidate the mechanisms underlying CD28 pathway blockade-mediated inhibition of alloantibodies in transplantation, and discuss recent clinical observations on the impact of belatacept on de novo and established HLA antibodies.

Recent Findings

The identification of T follicular helper cells as the CD4+ T cell subset required for optimal humoral immunity, along with newly identified roles for CD28 and the B7 molecules on B cell lineage cells has begun to pave the way for improved understanding and discovery of the mechanisms of CD28 costimulation blockade-mediated antibody inhibition. There has been resurgent clinical interest in the ability of belatacept to attenuate alloantibody responses. New reports have continued to document its ability to prevent de novo antibody responses, and more recent studies have surfaced exploring its potential to control nascent or pre-existing HLA antibodies.

Summary

A growing understanding of the mechanisms of anti-CD28-mediated alloantibody inhibition and continued clinical successes will guide the clinical optimization of belatacept and next generation CD28 blockers to prevent and reduce alloantibodies over the long-term.