Anti‐HLA sensitization in extensively burned patients: extent,associated factors,and reduction in potential access to vascularized composite allotransplantation

Extensively burned patients receive iterative blood transfusions and skin allografts that often lead to HLA sensitization, and potentially impede access to vascularized composite allotransplantation (VCA). In this retrospective, single‐center study, anti‐HLA sensitization was measured by single‐antigen‐flow bead analysis in patients with deep, second‐ and third‐degree burns over ≥40% total body surface area (TBSA). Association of HLA sensitization with blood transfusions, skin allografts, and pregnancies was analyzed by bivariate analysis. The eligibility for transplantation was assessed using calculated panel reactive antibodies (cPRA). Twenty‐nine patients aged 32 ± 14 years, including 11 women, presented with a mean burned TBSA of 54 ± 11%. Fifteen patients received skin allografts, comprising those who received cryopreserved (n = 3) or glycerol‐preserved (n = 7) allografts, or both (n = 5). An average 36 ± 13 packed red blood cell (PRBC) units were transfused per patient. In sera samples collected 38 ± 13 months after the burns, all patients except one presented with anti‐HLA antibodies, of which 13 patients (45%) had complement‐fixing antibodies. Eighteen patients (62%) were considered highly sensitized (cPRA≥85%). Cryopreserved, but not glycerol‐preserved skin allografts, history of pregnancy, and number of PRBC units were associated with HLA sensitization. Extensively burned patients may become highly HLA sensitized during acute care and hence not qualify for VCA. Alternatives to skin allografts might help preserve their later access to VCA.     

Vascularized Bone Marrow‐Based Immunosuppression Inhibits Rejection of Vascularized Composite Allografts in Nonhuman Primates

Vascularized composite allograft (VCA) transplantation (also referred to as composite tissue allotransplantation) has demonstrated clinical success in cases of hand, arm and face transplantation despite prior belief that skin provides an insurmountable barrier to allograft rejection. These overall good outcomes are facilitated by substantial immunosuppressive requirements in otherwise healthy patients, yet still demonstrate frequent rejection episodes. We developed a nonhuman primate model of facial segment allotransplantation to elucidate the unique pathophysiology and immunosuppressive requirements of VCA with addition of concomitant vascularized bone marrow (VBM). Heterotopically transplanted facial segment VCA with VBM treated only with tacrolimus and mycophenolate mofetil (MMF) demonstrated prolonged rejection‐free survival, compared to VCA without VBM that demonstrated early rejection episodes and graft loss. While VCA with VBM demonstrated sporadic macrochimerism, acute and chronic rejection and graft loss occurred after discontinuation of immunosuppression. These data support an immunomodulatory role of VBM in VCA that reduces immunosuppressive requirements while providing improved outcomes.     

Antibody‐mediated rejection in hand transplantation

Clinical relevance of antibody‐mediated rejection (ABMR) in vascularized composite allotransplantation (VCA) has not been defined. We herein describe a novel type of donor‐specific antibody (DSA) and B‐cell‐associated rejection in hand transplantation. In 2003, a bilateral forearm transplantation was performed on a 42‐year‐old male patient. In 2012, the patient presented with edematous hands and forearms without skin lesions. Punch skin biopsies revealed rejection grade Banff II. Immunohistochemical analysis identified large aggregates of CD20 +  lymphocytes with an architecture resembling lymph nodes. De novo DSA was found at a high level. Steroid treatment was ineffective, but administration of rituximab resulted in complete remission of clinical symptoms, evaporation of B‐cell aggregates, and disappearance of DSA. We herein report the first case of what we suggest is an ABMR in VCA occurring at 9 years after forearm transplantation. Rituximab therapy successfully reversed the event.     

Adipose‐derived stromal cell therapy combined with a short course nonmyeloablative conditioning promotes long‐term graft tolerance in vascularized composite allotransplantation

The risks of chronic immunosuppression limit the utility of vascularized composite allotransplantation (VCA) as a reconstructive option in complex tissue defects. We evaluated a novel, clinically translatable, radiation‐free conditioning protocol that combines anti‐lymphocyte serum (ALS), tacrolimus, and cytotoxic T‐lymphocyte‐associated protein 4 immunoglobulin (CTLA4‐Ig) with adipose‐derived stromal cells (ASCs) to allow VCA survival without long‐term systemic immunosuppression. Full‐mismatched rat hind‐limb‐transplant recipients received tacrolimus (0.5 mg/kg) for 14 days and were assigned to 4 groups: controls (CTRL) received no conditioning; ASC‐group received CTLA4‐Ig (10 mg/kg body weight i.p. postoperative day [POD] 2, 4, 7) and donor ASCs (1 × 10⁶ iv, POD 2, 4, 7, 15, 28); the ASC‐cyclophosphamide (CYP)‐group received CTLA4‐Ig, ASC plus cyclophosphamide (50 mg/kg ip, POD 3); the ASC‐ALS‐group received CTLA4‐Ig, ASCs plus ALS (500 µL ip, POD 1, 5). Banff grade III or 120 days were endpoints. ASCs suppressed alloresponse in vitro. Median rejection‐free VCA survival was 28 days in CTRL (n = 7), 34 in ASC (n = 6), and 27.5 in ASC‐CYP (n = 4). In contrast, ASC‐ALS achieved significantly longer, rejection‐free VCA survival in 6/7 animals (86%), with persistent mixed donor‐cell chimerism, and elevated systemic and allograft skin T_regs, with no signs of acute cellular rejection. Taken together, a regimen comprised of short‐course tacrolimus, repeated CTLA4‐Ig and ASC administration, combined with ALS, promotes long‐term VCA survival without chronic immunosuppression.     

Belgian multicenter experience with intestinal transplantation

Intestinal transplantation (ITx) has evolved from an experimental procedure toward a clinical reality but remains a challenging procedure. The aim of this survey was to analyze the multicenter Belgian ITx experience. From 1999 to 2014, 24 ITx in 23 patients were performed in Belgium, divided over five centers. Median recipient age was 38 years (8 months–57 years); male/female ratio was 13/10; six were children; and 17 adults. Intestinal failure was related to intestinal ischemia (n = 5), volvulus (n = 5), splanchnic thrombosis (n = 4), Crohn (n = 2), pseudo‐obstruction (n = 2), microvillus inclusion (n = 2), Churg‐Strauss (n = 1), necrotizing enterocolitis (n = 1), intestinal atresia (n = 1), and chronic rejection (n = 1). Graft type was isolated ITx (n = 9), combined liver‐ITx (n = 11) and multivisceralTx (n = 4). One was a living donor‐related transplantation and five patients received simultaneously a kidney graft. Early acute rejection occurred in 8; late acute rejection in 4; and chronic rejection in 2. Two patients developed a post‐transplant lymphoproliferative disease. Nine patients have died. Among 14 survivors at last follow‐up, 11 have been transplanted for more than 1 year. None of the latter has developed renal failure, and all were nutritionally independent with a Karnofsky score > 90%. One‐/five‐year patient and graft survivals were 71.1%, 62.8%, 58.7% and 53.1%, respectively. Based on this experience, ITx has come of age in Belgium as a lifesaving and potentially quality of life restoring therapy.     

Lymphoid Neogenesis in Murine Cardiac Allografts Undergoing Chronic Rejection

Lymphoid neogenesis is the process by which ectopic lymphoid accumulations that resemble lymph nodes arise in nonlymphoid tissues. Such lymphoid accumulations, known as tertiary lymphoid organs (TLO), are observed in chronic autoimmunity and they propagate immune pathology by setting up local antigen presenting sites. Whether lymphoid neogenesis occurs in transplanted organs and contributes to rejection is not well understood. To begin to address this question, we retrospectively analyzed 319 murine cardiac allografts for microscopic evidence of lymph-node-like structures. We found 78 allografts that had either classical TLO, characterized by discrete T- and B-cell zones and high endothelial venules (HEV) expressing peripheral node addressin (PNAd) (n = 34), or PNAd(+) HEV without organized lymphoid accumulations (n = 44). These changes were present in both short- and long-lived allografts and were invariably associated with rejection. Importantly, they occurred in 78% of allografts undergoing chronic rejection (n = 85) but in only 7% of allografts undergoing primarily acute rejection (n = 184). These findings indicate that, like autoimmunity, alloimmunity is associated with lymphoid neogenesis in the target organ and suggest a role for local T-cell activation in chronic allograft rejection.     

Subcutaneous administration of a neutralizing IL‐1β antibody prolongs limb allograft survival

Cytokine‐expression profiles revealed IL‐1ß highly upregulated in rejecting skin of limb allografts. We investigate the effect of intragraft treatment with a neutralizing IL‐1β antibody in limb transplantation. Following allogenic hind‐limb transplantation, Lewis rats were either left untreated 1 or treated with anti‐lymphocyte serum + tacrolimus (baseline) 2 ; baseline immunosuppression + anti‐IL‐1β (1 mg/kg once/week, 6‐8 subcutaneous injections) into the transplanted 3 or contralateral 4 limb. Endpoint was rejection grade III or day 100. Graft rejection was assessed by histology, immunohistochemistry, flow cytometry phenotyping of immune cells, and monitoring cytokine expression. Anti‐IL‐1β injections into the allograft or contralateral limb resulted in a significant delay of rejection onset (controls: 58.60 ± 0.60; group 3: 75.80 ± 10.87, P = .044; group 4: 73.00 ± 6.49, P = .008) and prolongation of graft survival (controls: 64.60 ± 0.87; group 3: 86.60 ± 5.33, P = .002; group 4: 93.20 ± 3.82, P = .002), compared to controls. Although the phenotype of the graft infiltrating immune cells did not differ between groups, significantly decreased skin protein levels of IL‐1β, IL‐4, IL‐13, IP‐10, MCP‐1, and MCP‐3 in long‐term‐survivors indicate an overall decrease of chemoattraction and infiltration of immune cells as the immunosuppressive mechanism of anti‐IL‐1β. Inhibition of IL‐1β with short‐term systemic immunosuppression prolongs limb allograft survival and represents a promising target for immunosuppression in extremity transplantation.     

Discovery of non‐HLA antibodies associated with cardiac allograft rejection and development and validation of a non‐HLA antigen multiplex panel: From bench to bedside

We analyzed humoral immune responses to nonhuman leukocyte antigen (HLA) after cardiac transplantation to identify antibodies associated with allograft rejection. Protein microarray identified 366 non‐HLA antibodies (>1.5 fold, P < .5) from a discovery cohort of HLA antibody–negative, endothelial cell crossmatch–positive sera obtained from 12 cardiac allograft recipients at the time of biopsy‐proven rejection. From these, 19 plasma membrane proteins and 10 autoantigens identified from gene ontology analysis were combined with 48 proteins identified through literature search to generate a multiplex bead array. Longitudinal sera from a multicenter cohort of adult cardiac allograft recipients (samples: n = 477 no rejection; n = 69 rejection) identified 18 non‐HLA antibodies associated with rejection (P < .1) including 4 newly identified non‐HLA antigenic targets (DEXI, EMCN, LPHN1, and SSB). CART analysis showed 5/18 non‐HLA antibodies distinguished rejection vs nonrejection. Antibodies to 4/18 non‐HLA antigens synergize with HLA donor‐specific antibodies and significantly increase the odds of rejection (P < .1). The non‐HLA panel was validated using an independent adult cardiac transplant cohort (n = 21 no rejection; n = 42 rejection, >1R) with an area under the curve of 0.87 (P < .05) with 92.86% sensitivity and 66.67% specificity. We conclude that multiplex bead array assessment of non‐HLA antibodies identifies cardiac transplant recipients at risk of rejection.     

Studies Introducing Costimulation Blockade for Vascularized Composite Allografts in Nonhuman Primates

Vascularized composite allografts (VCAs) are technically feasible. Similar to other organ transplants, VCAs are hampered by the toxicity and incomplete efficacy associated with conventional immunosuppression. Complications attributable to calcineurin inhibitors remain prevalent in the clinical cases reported to date, and these loom particularly large given the nonlifesaving nature of VCAs. Additionally, acute rejection remains almost ubiquitous, albeit controllable with current agents. Costimulation blockade offers the potential to provide prophylaxis from rejection without the adverse consequences of calcineurin‐based regimens. In this study, we used a nonhuman‐primate model of VCA in conjunction with immunosuppressive regimens containing combinations of B7‐specific costimulation blockade with and without adhesion blockade with LFA3‐Ig to determine what adjunctive role these agents could play in VCA transplantation when combined with more conventional agents. Compared to tacrolimus, the addition of belatacept improved rejection free allograft survival. The combination with LFA3‐Ig reduced CD2^hi memory T cells, however did not provide additional protection against allograft rejection and hindered protective immunity. Histology paralleled clinical histopathology and Banff grading. These data provide the basis for the study of costimulation blockade in VCA in a relevant preclinical model.     

Molecular Markers and Targeted Therapy of Skin Rejection in Composite Tissue Allotransplantation

Skin rejection remains a major hurdle in reconstructive transplantation. We investigated molecular markers of skin rejection with particular attention to lymphocyte trafficking. Skin biopsies (n = 174) from five human hand transplant recipients were analyzed for rejection, characteristics of the infiltrate and lymphocytic adhesion markers. The cellular infiltrate predominantly comprised CD3+ T cells. CD68, Foxp3 and indoleamine 2, 3‐dioxygenase expression and the CD4/CD8 increased with severity of rejection. Lymphocyte adhesion markers were upregulated upon rejection, intercellular adhesion molecule‐1 and E‐selectin correlated best with severity of rejection. Guided by the findings, a specific E‐ and P‐selectin inhibitor was investigated for its effect on skin rejection in a rat hind limb allotransplant model. While efomycine M (weekly s.c. injection into the graft) alone had no effect, long‐term allograft survival was achieved when combined with antithymocyte globulin and tacrolimus (control group without efomycine M rejected at postoperative day [POD] 61 ± 1). Upregulation of lymphocyte trafficking markers correlates with severity of skin rejection and time after transplantation in human hand transplantation. Blocking E‐ and P‐selectin in the skin holds potential to significantly prolong limb allograft survival.     

Cytomegalovirus Latency Promotes Cardiac Lymphoid Neogenesis and Accelerated Allograft Rejection in CMV Naïve Recipients

Human cytomegalovirus (HCMV) infection is associated with the acceleration of transplant vascular sclerosis (TVS) and chronic allograft rejection (CR). HCMV‐negative recipients of latently HCMV infected donor grafts are at highest risk for developing CMV disease. Using a rat heart transplant CR model, we have previously shown that acute rat CMV (RCMV) infection following transplantation significantly accelerates both TVS and CR. Here, we report that RCMV‐naïve recipients of heart allografts from latently RCMV‐infected donors undergo acceleration of CR with similar kinetics as acutely infected recipients. In contrast to acutely infected recipients, treatment of recipients of latently infected donor hearts with ganciclovir did not prevent CR or TVS. We observed the formation of tertiary lymphoid structures (TLOs) containing macrophages and T cells in latently infected hearts prior to transplantation but not in uninfected rats. Moreover, pathway analysis of gene expression data from allografts from latently infected donors indicated an early and sustained production of TLO‐associated genes compared to allografts from uninfected donors. We conclude that RCMV‐induced TLO formation and alteration of donor tissue T cell profiles prior to transplantation in part mediate the ganciclovir‐insensitive rejection of latently infected donor allografts transplanted into naïve recipients by providing a scaffold for immune activation.     

Increasing access to renal transplantation in India through our single‐center kidney paired donation program: a model for the developing world to prevent commercial transplantation

Because access to transplantation with HLA‐desensitization protocols and ABO incompatible transplantation is very limited due to high costs and increased risk of infections from more intense immunosuppression, kidney paired donation (KPD) promises hope to a growing number of end‐stage renal disease (ESRD) patient in India. We present a government and institutional ethical review board approved study of 56 ESRD patients [25 two‐way and 2 three‐way pairs] who consented to participate in KPD transplantation at our center in 2013, performed to avoid blood group incompatibility (n = 52) or positive cross‐match (n = 4). All patients had anatomic, functional, and immunologically comparable donors. The waiting time in KPD was short as compared to deceased donor transplantation. Laparoscopic donor nephrectomy was performed in 54 donors. Donor relationships were spousal (n = 40), parental (n = 13), others (n = 3), with median HLA match of 1. Graft survival was 97.5%. Three patients died with functioning graft. 16% had biopsy‐proven acute rejection. Mean serum creatinine was 1.2 mg/dl at 0.73 ± 0.32 months follow‐up. KPD is a viable, legal, and rapidly growing modality for facilitating LDRT for patients who are incompatible with their healthy, willing living donor. To our knowledge, this is the largest single‐center report from India.     

Long‐Term Lung Transplantation in Nonhuman Primates

Despite advances in surgical technique and clinical care, lung transplantation still remains a short‐term solution for the treatment of end‐stage lung disease. To date, there has been limited experience in experimental lung transplantation using nonhuman primate models. Therefore, we have endeavored to develop a long‐term, nonhuman primate model of orthotopic lung transplantation for the ultimate purpose of designing protocols to induce tolerance of lung grafts. Here, we report our initial results in developing this model and our observation that the nonhuman primate lung is particularly prone to rejection. This propensity toward rejection may be a consequence of 1) upregulated nonspecific inflammation, and 2) a larger number of pre‐existing alloreactive memory T cells, leading to augmented deleterious immune responses. Our data show that triple‐drug immunosuppression mimicking clinical practice is not sufficient to prevent acute rejection in nonhuman primate lung transplantation. The addition of horse‐derived anti‐thymocyte globulin and a monoclonal antibody to the IL‐6 receptor allowed six out of six lung recipients to be free of rejection for over 120 days.     

Clinical relevance of the de novo production of anti‐HLA antibodies following intestinal and multivisceral transplantation

Despite a negative pretransplant cross‐match, intestinal transplant recipients can mount humoral immune responses soon after transplantation. Moreover, the development of donor‐specific anti‐HLA antibodies (DSAs) is associated with severe graft injury. Between June 2000 and August 2011, 30 patients (median age 37.6 ± 9.8 years) received isolated intestinal transplantations (ITX, n = 18) or multivisceral transplantations (MVTXs, n = 12) at our center. We screened for human leukocyte antigen (HLA) antibodies pre‐ and post‐transplant. If patients produced DSAs, treatment with plasmapheresis and intravenous immunoglobulin (IVIG) was initiated. In the event of DSA persistence and/or treatment‐refractory rejection, rituximab and/or bortezomib were added. Ten patients developed DSAs and simultaneously showed significant signs of rejection. These patients received plasmapheresis and IVIG. Eight patients additionally received rituximab, and two patients were treated with bortezomib. DSA values decreased upon antirejection therapy in 8 of the 10 patients. The development of DSAs following ITX is often associated with acute rejection. We observed that the number of mismatched antigens and epitopes correlates with the probability of developing de novo DSAs. Early diagnosis and therapy, including B‐cell depletion and plasma cell inhibition, are crucial to preventing further graft injury.     

Differences in glucose‐stimulated insulin secretion in vitro of islets from human,nonhuman primate,and porcine origin

Porcine islet xenotransplantation is considered a potential cell‐based therapy for type 1 diabetes. It is currently being evaluated in diabetic nonhuman primates (NHP) to assess safety and efficacy of the islet product. However, due to a variety of distinct differences between the respective species, including the insulin secretory characteristics of islets, the suitability and predictive value of the preclinical model in the extrapolation to the clinical setting remain a critical issue. Islets isolated from human (n = 3), NHP (n = 2), adult pig (AP, n = 3), and juvenile pig (JP, n = 4) pancreata were perifused with medium at basal glucose (2.5 mm ) followed by high glucose (16.7 mm ) concentrations. The total glucose‐stimulated insulin secretion (GSIS) was calculated from generated insulin secretion profiles. Nonhuman primate islets exhibited GSIS 3‐fold higher than AP islets, while AP and JP islets exhibited GSIS 1/3 and 1/30 of human islets, respectively. The insulin content of NHP and AP islets was similar to that of human islets, whereas that of JP islets was 1/5 of human islets. Despite the fact that human, NHP, and AP islets contain similar amounts of insulin, the much higher GSIS for NHP islets than for AP and JP islets suggests the need for increased dosing of islets from JP and AP in pig‐to‐NHP transplantation. Porcine islet xenotransplantation to humans may require significantly higher dosing given the lower GSIS of AP islets compared to human islets.     

Outcomes in Pancreas Transplantation With Exocrine Drainage Through a Duodenoduodenostomy Versus Duodenojejunostomy

Until recently, pancreas transplantation has mostly been performed with exocrine drainage via duodenojejunostomy (DJ). Since 2012, DJ was substituted with duodenoduodenostomy (DD) in our hospital, allowing endoscopic access for biopsies. This study assessed safety profiles with DD versus DJ procedures and clinical outcomes with the DD technique in pancreas transplantation. DD patients (n = 117; 62 simultaneous pancreas–kidney [SPK_DD] and 55 pancreas transplantation alone [PTA_DD] with median follow‐up 2.2 years) were compared with DJ patients (n = 179; 167 SPK_DJ and 12 PTA_DJ) transplanted in the period 1998–2012 (pre‐DD era). Postoperative bleeding and pancreas graft vein thrombosis requiring relaparotomy occurred in 17% and 9% of DD patients versus 10% (p = 0.077) and 6% (p = 0.21) in DJ patients, respectively. Pancreas graft rejection rates were still higher in PTA_DD patients versus SPK_DD patients (p = 0.003). Hazard ratio (HR) for graft loss was 2.25 (95% CI 1.00, 5.05; p = 0.049) in PTA_DD versus SPK_DD recipients. In conclusion, compared with the DJ procedure, the DD procedure did not reduce postoperative surgical complications requiring relaparatomy or improve clinical outcomes after pancreas transplantation despite serial pancreatic biopsies for rejection surveillance. It remains to be seen whether better rejection monitoring in DD patients translates into improved long‐term pancreas graft survival.     

Human leukocyte antigen matching in heart transplantation: systematic review and meta‐analysis

Allocation of donors with regard to human leukocyte antigen (HLA) is controversial in heart transplantation. This paper is a systematic review and meta‐analysis of the available evidence. PubMed, Embase, and the Cochrane Library were searched systematically for studies that addressed the effects of HLA matching on outcome after heart transplantation. Fifty‐seven studies met the eligibility criteria. 34 studies had graft rejection as outcome, with 26 of the studies reporting a significant reduction in graft rejection with increasing degree of HLA matching. Thirteen of 18 articles that reported on graft failure found that it decreased significantly with increasing HLA match. Two multicenter studies and nine single‐center studies provided sufficient data to provide summary estimates at 12 months. Pooled comparisons showed that graft survival increased with fewer HLA‐DR mismatches [0–1 vs. 2 mismatches: risk ratio (RR) = 1.09 (95% confidence interval (CI): 1.01–1.19; P = 0.04)]. Having fewer HLA‐DR mismatches (0–1 vs. 2) reduced the incidence of acute rejection [(RR = 0.81 (0.66–0.99; P = 0.04)]. Despite the considerable heterogeneity between studies, the short observation time, and older data, HLA matching improves graft survival in heart transplantation. Prospective HLA‐DR matching is clinically feasible and should be considered as a major selection criterion.     

Solid phase detection of C4d‐fixing HLA antibodies to predict rejection in high immunological risk kidney transplant recipients

Protocols for recipient desensitization may allow for successful kidney transplantation across major immunological barriers. Desensitized recipients, however, still face a considerable risk of antibody‐mediated rejection (AMR), which underscores the need for risk stratification tools to individually tailor treatment. Here, we investigated whether solid phase detection of complement‐fixing donor‐specific antibodies (DSA) has the potential to improve AMR prediction in high‐risk transplants. The study included 68 sensitized recipients of deceased donor kidney allografts who underwent peritransplant immunoadsorption for alloantibody depletion (median cytotoxic panel reactivity: 73%; crossmatch conversion: n = 21). Pre and post‐transplant sera were subjected to detection of DSA‐triggered C4d deposition ([C4d]DSA) applying single‐antigen bead (SAB) technology. While standard crossmatch and [IgG]SAB testing failed to predict outcomes in our desensitized patients, detection of preformed [C4d]DSA (n = 44) was tightly associated with C4d‐positive AMR [36% vs. 8%, P = 0.01; binary logistic regression: odds ratio: 10.1 (95% confidence interval: 1.6–64.2), P = 0.01]. Moreover, long‐term death‐censored graft survival tended to be worse among [C4d]DSA‐positive recipients (P = 0.07). There were no associations with C4d‐negative AMR or cellular rejection. [C4d]DSA detected 6 months post‐transplantation were not related to clinical outcomes. Our data suggest that pretransplant SAB‐based detection of complement‐fixing DSA may be a valuable tool for risk stratification.     

Preemptive treatment of early donor‐specific antibodies with IgA‐ and IgM‐enriched intravenous human immunoglobulins in lung transplantation

This retrospective study presents our 4‐year experience of preemptive treatment of early anti‐HLA donor specific antibodies with IgA‐ and IgM‐enriched immunoglobulins. We compared outcomes between patients with antibodies and treatment (case patients) and patients without antibodies (control patients). Records of patients transplanted at our institution between March 2013 and November 2017 were reviewed. The treatment protocol included one single 2 g/kg immunoglobulin infusion followed by successive 0.5 g/kg infusions for a maximum of 6 months, usually combined with a single dose of anti‐CD20 antibody and, in case of clinical rejection or positive crossmatch, with plasmapheresis or immunoabsorption. Among the 598 transplanted patients, 128 (21%) patients formed the case group and 452 (76%) the control group. In 116 (91%) patients who completed treatment, 106 (91%) showed no antibodies at treatment end. Fourteen (13%) patients showed antibody recurrence thereafter. In case versus control patients and at 4‐year follow‐up, respectively, graft survival (%) was 79 versus 81 (P = .59), freedom (%) from biopsy‐confirmed rejection 57 versus 53 (P = .34), and from chronic lung allograft dysfunction 82 versus 78 (P = .83). After lung transplantation, patients with early donor‐specific antibodies and treated with IgA‐ and IgM‐enriched immunoglobulins had 4‐year graft survival similar to patients without antibodies and showed high antibody clearance.     

Dual targeting: Combining costimulation blockade and bortezomib to permit kidney transplantation in sensitized recipients

Previous evidence suggests that a homeostatic germinal center (GC) response may limit bortezomib desensitization therapy. We evaluated the combination of costimulation blockade with bortezomib in a sensitized non‐human primate kidney transplant model. Sensitized animals were treated with bortezomib, belatacept, and anti‐CD40 mAb twice weekly for a month (n = 6) and compared to control animals (n = 7). Desensitization therapy–mediated DSA reductions approached statistical significance (P = .07) and significantly diminished bone marrow PCs, lymph node follicular helper T cells, and memory B cell proliferation. Graft survival was prolonged in the desensitization group (P = .073). All control animals (n = 6) experienced graft loss due to antibody‐mediated rejection (AMR) after kidney transplantation, compared to one desensitized animal (1/5). Overall, histological AMR scores were significantly lower in the treatment group (n = 5) compared to control (P = .020). However, CMV disease was common in the desensitized group (3/5). Desensitized animals were sacrificed after long‐term follow‐up with functioning grafts. Dual targeting of both plasma cells and upstream GC responses successfully prolongs graft survival in a sensitized NHP model despite significant infectious complications and drug toxicity. Further work is planned to dissect underlying mechanisms, and explore safety concerns.