Donor‐specific anti‐HLA antibodies detected by Luminex: predictive for short‐term but not long‐term survival after heart transplantation

In heart transplantation, the clinical significance of pretransplant donor‐specific antibodies (DSA) detected by solid phase assay (SPA), which is more sensitive than the conventional complement‐dependent cytotoxicity (CDC) assays, is unclear. The aim was to evaluate SPA performed on pretransplant sera for survival after heart transplantation. Pretransplant sera of 272 heart transplant recipients were screened for anti‐HLA antibodies using CDC and SPA. For determination of pretransplant DSA, a single‐antigen bead assay was performed. The presence of anti‐HLA antibodies was correlated with survival. Secondary outcome parameters were acute cellular rejection, graft coronary vasculopathy and ejection fraction. In Kaplan–Meier analysis, SPA‐screening did not predict survival (P = 0.494), this in contrast to CDC screening (P = 0.002). However, the presence of pretransplant DSA against HLA class I was associated with decreased short‐term survival compared to non‐DSA (P = 0.038). ROC curve analysis showed a sensitivity of 76% and specificity of 73% at a cutoff of 2000 MFI. In contrast, the presence of anti‐HLA antibodies had no influence on long‐term survival, rejection incidence, and graft function. Thus, detection of DSA class I in pretransplant serum is a strong predictor of short‐term, but not long‐term survival and may help in the early management of heart transplant patients.     

Eculizumab Salvage Therapy for Antibody‐Mediated Rejection in a Desensitization‐Resistant Intestinal Re‐Transplant Patient

The presence of elevated calculated panel reactive antibody (cPRA) and anti‐HLA donor specific antibodies (DSA) are high risk factors for acute antibody‐mediated rejection (AAMR) in intestinal transplantation that may lead to graft loss. Eculizumab has been used for the treatment of AAMR in kidney transplantation of sensitized patients that do not respond to other treatment. Here, we report a case where eculizumab was used to treat AAMR in a desensitization‐resistant intestinal re‐transplant patient. A male patient lost his intestinal graft to AAMR 8.14 years after his primary transplant. He received a second intestinal graft that had to be explanted a month later due to refractory AAMR. The patient remained highly sensitized despite multiple treatments. He received a multivisceral graft and presented with severe AAMR on day 3 posttransplantation. The AAMR was successfully treated with eculizumab. The patient presently maintains an elevated cPRA level above 90% but his DSAs have decreased from 18 000 MFI (mean fluorescent intensity) to below the positive cut‐off value of 3000 MFI and remains rejection free with a 2‐year follow‐up since his multivisceral transplant. Eculizumab offers an alternative to treat AAMR in intestinal transplantation in desensitization‐resistant patients.     

Impact of pretransplant donor‐specific antibodies on kidney allograft recipients with negative flow cytometry cross‐matches

The Luminex test can detect low levels of donor‐specific antibody (DSA) that cannot be detected by flow‐cytometric cross‐matching (FCXM) in kidney transplantation (KT). This study evaluated the impact of DSA on clinical outcomes in KT recipients negative on FCXM. Of 575 consecutive patients who underwent living donor KT between January 2013 and July 2016, 494 (85.9%) were DSA‐negative and 81 (14.1%) were DSA‐positive. Although rates of acute cellular rejection (ACR) at 1 year were similar in the 2 groups (P = .54), the incidence of antibody‐mediated rejection (ABMR) was significantly higher in the DSA‐positive group (P < .01). There was no statistically significant association between rejection‐free graft survival (RFGS) rates and pretransplant class I DSA. However, evaluation of pretransplant class II DSA showed that RFGS rates were significantly lower in patients with mean fluorescence intensity (MFI) >3000 than in patients with DSA‐negative (P < .01). On multivariate analyses, class II DSA MFI ≥5000 was a significant risk factor for acute rejection (hazard ratio, 7.48; P < .01). These findings suggested that pretransplant DSA alone did not affect graft survival in KT recipients without desensitization. However, class II DSA MFI >5000 was an independent predictor of acute rejection in DSA‐positive patients.     

Bortezomib as the Sole Post‐Renal Transplantation Desensitization Agent Does Not Decrease Donor‐Specific Anti‐HLA Antibodies

Persistence of donor‐specific anti‐HLA antibodies (DSA) associated with antibody‐mediated graft injuries following kidney transplantation predicts evolution toward chronic humoral rejection and reduced graft survival. Targeting plasma cells, the main antibody‐producing cells, with the proteasome inhibitor bortezomib may be a promising desensitization strategy. We evaluated the in vivo efficacy of one cycle of bortezomib (1.3 mg/m²× 4 doses), used as the sole desensitization therapy, in four renal transplant recipients experiencing subacute antibody‐mediated rejection with persisting DSA (>2000 [Mean Fluorescence Intensity] MFI). Bortezomib treatment did not significantly decrease DSA MFI within the 150‐day posttreatment period in any patient. In addition, antivirus (HBV, VZV and HSV) antibody levels remained stable following treatment suggesting a lack of efficacy on long‐lived plasma cells. In conclusion, one cycle of bortezomib alone does not decrease DSA levels in sensitized kidney transplant recipients in the time period studied. These results underscore the need to evaluate this new desensitization agent properly in prospective, randomized and well‐controlled studies.     

Allosensitization after transplant failure: the role of graft nephrectomy and immunosuppression – a retrospective study

There are conflicting data about the role of transplant nephrectomy and immunosuppression withdrawal on the development of allosensitization and the impact on re‐transplantation. We divided 109 first graft recipients into two groups according to whether they underwent nephrectomy (NX+, n = 61) or their graft was left in situ (NX?, n = 48). Sera were assessed for HLA‐A/B/Cw/DR/DQ antibodies at the time of NX/transplant failure and after 3, 6, 12, 24 months. The NX+ group showed a higher rate of donor specific antibody (DSA) and non‐DSA human leukocyte antigen (HLA) antibody production at all the time points. Multivariable analysis showed that nephrectomy was a strong, independent risk factor for the development of DSAs after 12 and 24 months (P = 0.005 and 0.008). In the NX? group, low tacrolimus levels correlated with DSA formation (AUC 0.817, P = 0.002; best cut‐off level 2.9 ng/ml). Analysis with a standardized pool of UK donors showed a more difficult grade of HLA matchability following nephrectomy compared with the NX? group. Nephrectomy is followed by the long‐term production of DSA and non‐DSA HLA antibodies and negatively impacts on the chances of finding a HLA‐compatible kidney. Tacrolimus levels ≥3 ng/ml are protective against the development of allosensitization and could facilitate re‐transplantation in the NX? group.     

Pre‐existing donor‐specific antibodies are detrimental to kidney allograft only when persistent after transplantation

Donor‐specific antibodies (DSA) increase the risk of allograft rejection and graft failure. They may be present before transplant or develop de novo after transplantation. Here, we studied the evolution of preformed DSA and their impact on graft outcome in kidney transplant recipients. Using the Luminex Single Antigen assay, we analyzed the sera on the day of transplantation of 239 patients who received a kidney transplant. Thirty‐seven patients (15.5%) had pre‐existing DSA detected the day of transplantation. After 5 years, the pre‐existing DSA disappeared in 22 patients whereas they persisted in 12. Variables associated with DSA persistence were age <50 years (P = 0.009), a history of previous transplantation (P = 0.039), the presence of class II DSA (P = 0.009), an MFI of preformed DSA >3500 (P < 0.001), and the presence of two or more DSA (P < 0.001). DSA persistence was associated with a higher risk of graft loss and antibody‐mediated rejection. Previously undetected preformed DSA are deleterious to graft survival only when they persist after transplantation.     

Markers of graft microvascular endothelial injury may identify harmful donor‐specific anti‐HLA antibodies and predict kidney allograft loss

Graft microvasculature is a major target of donor‐specific antibodies (DSA) and endothelial damage is direct evidence of antibody‐mediated rejection (ABMR). Using immunohistochemistry, we analyzed the expression of three microvascular endothelial activation markers (fascin, vimentin, and hsp47), suggestive of endothelial‐to‐mesenchymal transition (EndMT) in 351 graft biopsies from 248 kidney recipients, with concomitant screening of circulating antihuman leukocyte antigen (HLA) DSA at the time of the biopsy. The factors associated with EndMT marker expression were DSA and the presence of microvascular inflammation (MI). EndMT expressing grafts had significantly more allograft loss compared to EndMT negative grafts (P < .0001). The expression of EndMT markers positively correlated with anti‐HLA DSA class II mean fluorescence intensity (MFI) levels and especially identified DQ and DR antibodies as being more closely associated with microvascular injury. Moreover, only DSA linked to positive EndMT score affected allograft survival, regardless of DSA MFI levels or presence of C4d deposition. Thus, EndMT markers could represent a clinically relevant tool for early identification of ongoing endothelial injury, harmful DSA, and patients at high risk for allograft failure.     

Influence of preoperative anti‐HLA antibodies on short‐ and long‐term graft survival in recipients with or without rituximab treatment

We investigated the relationship between preoperative anti‐HLA antibodies (donor‐specific antibody, DSA) and the graft survival rate in recipients who had or had not received rituximab (Rit) treatment. The subjects were categorized into four groups as follows: DSA+Rit?, n = 39; DSA?Rit?, n = 121; DSA+Rit+, n = 74; and DSA?Rit+, n = 47. We examined the influence of preoperative DSA on the incidence of graft rejection and the survival rate of recipients who had or who had not received rituximab before transplantation. The 6‐month acute rejection rates based on graft biopsies were 39%, 19%, 15%, and 0% for the DSA+Rit?, DSA?Rit?, DSA+Rit+, and DSA?Rit+ groups. The rates of chronic antibody‐mediated rejection after more than 6 months were 50%, 22%, 18%, and 0%. The 5‐year graft survival rate was significantly lower in the DSA+Rit? group (84%) than in the other groups (95% for DSA?Rit?, 98% for DSA+Rit+, and 91% for DSA?Rit+). The rate of the appearance of de novo anti‐HLA antibodies was higher in the groups that did not receive rituximab treatment. The rate of graft loss associated with chronic antibody‐mediated rejection was also higher in the DSA+Rit? group than in the other groups (P = 0.01). The presence of DSA and the administration of rituximab had strong impacts on not only short‐term graft rejection, but also long‐term graft rejection and its association with the graft survival time.     

Determining donor‐specific antibody C1q‐binding ability improves the prediction of antibody‐mediated rejection in human leucocyte antigen‐incompatible kidney transplantation

Detrimental impact of preformed donor‐specific antibodies (DSAs) against human leucocyte antigens on outcomes after kidney transplantation are well documented, however, the value of their capacity to bind complement for predicting antibody‐mediated rejection (AMR) and graft survival still needs to be confirmed. We aimed to study DSA characteristics (strength and C1q binding) that might distinguish harmful DSA from clinically irrelevant ones. We retrospectively studied 60 kidney‐transplanted patients with preformed DSA detected by single antigen bead (SAB) assays (IgG and C1q kits), from a cohort of 517 kidney graft recipients (124 with detectable anti‐HLA antibodies). Patients were divided into DSA strength (MFI < vs. ≥ 15 000) and C1q‐binding ability. AMR frequency was high (30%) and it increased with DSA strength (P = 0.002) and C1q+ DSA (P < 0.001). The performance of DSA C1q‐binding ability as a predictor of AMR was better than DSA strength (diagnostic odds ratio 16.3 vs. 6.4, respectively). Furthermore, a multivariable logistic regression showed that C1q+ DSA was a risk factor for AMR (OR = 16.80, P = 0.001), while high MFI DSAs were not. Graft survival was lower in high MFI C1q+ DSA in comparison with patients with C1q? high or low MFI DSA (at 6 years, 38%, 83% and 80%, respectively; P = 0.001). Both DSA strength and C1q‐binding ability assessment seem valuable for improving pretransplant risk assessment. Since DSA C1q‐binding ability was a better predictor of AMR and correlated with graft survival, C1q‐SAB may be a particularly useful tool.     

Differential outcomes in 3 types of acute antibody‐mediated rejection

Abstract: Introduction: The aim of this study is to investigate the prevalence, predictors, and clinical outcomes of acute antibody‐mediated rejection (AAMR). Methods: Retrospective analysis of 833 adult patients who received kidney transplantation between 1/1/2001 and 8/15/2007. Results: The prevalence of AAMR and acute cellular rejection was 2% and 8.2%, respectively. Eight patients had type I, seven type II, and two type III AAMR. All patients had at least one strong donor‐specific anti‐HLA antibodies (DSA) with a median fluorescence intensity (MFI) value of over 6000 and the mean number of strong DSAs was 2.0 ± 0.7. Fifteen of 17 patients received pre‐transplant desensitization treatment. During a median 28 months of follow‐up (range: 12–38 months), two patients died (88% patient survival), and nine lost their allografts (35% graft survival). While all type I AAMR patients responded to treatment, all type III patients, and four of seven patients with type II AAMR lost their allografts earlier, and three type II AAMR patients later due to transplant glomerulopathy. Conclusions: AAMR is mainly seen in patients with pre‐transplant strong DSAs. There is a striking difference in clinical outcomes of AAMR that types II and III AAMR patients have poor prognosis compared to type I AAMR patients.     

Donor‐specific HLA antibodies: evaluating the risk for graft loss in renal transplant recipients with isotype switch from complement fixing IgG1/IgG3 to noncomplement fixing IgG2/IgG4 anti‐HLA alloantibodies

Human leukocyte antigen alloantibodies have a multitude of damaging effects on the allograft, both complement (C′) activation and Fc‐independent ones. To date, the clinical significance of non‐C′ fixing (NCF) HLA donor‐specific antibodies (DSA) is still unclear. In this study, we investigated whether renal transplant recipients with NCF‐DSA subclasses (IgG2/IgG4, IgA1/IgA2) are at higher risk of graft loss compared to patients with exclusively C′ fixing (IgG1/IgG3). Blood samples from 274 patients were analyzed for HLA IgG and IgA subclasses using a modified single‐antigen bead assay. We identified 50 (18.2%) patients with circulating NCF antibodies either DSA (n = 17) or against third‐party HLA (n = 33). NCF‐DSAs were preferentially of IgG2/IgG4 isotype (11/17) and were mainly directed against HLA class II (13/17). NCF DSA were present as a mixture with strong C′ fixing IgG1/IgG3. Graft survival was similar between patients with exclusively C′ fixing antibodies and those with a mixture panel (log rang test P = 0.162), and also among patients with different immunoglobulin isotype and subclasses (long‐rank test, P = 0.732). We conclude that expansion of DSA to NCF subclasses postrenal transplantation does not seem to be associated with worse graft survival as compared to the presence of exclusive C′ fixing subclasses.     

Influenza vaccination and humoral alloimmunity in solid organ transplant recipients

Annual influenza vaccination is recommended in solid organ transplant (SOT) recipients. However, concerns have been raised about the impact of vaccination on antigraft alloimmunity. We evaluated the humoral alloimmune responses to influenza vaccination in a cohort of SOT recipients between October 2008 and December 2011. Anti‐HLA antibodies were measured before and 4–8 weeks after influenza vaccination using a solid‐phase assay. Overall, 169 SOT recipients were included (kidney = 136, lung = 26, liver = 3, and combined = 4). Five (2.9%) of 169 patients developed de novo anti‐HLA antibodies after vaccination, including one patient who developed donor‐specific antibodies (DSA) 8 months after vaccination. In patients with pre‐existing anti‐HLA antibodies, median MFI was not significantly different before and after vaccination (P = 0.73 for class I and P = 0.20 for class II anti‐HLA antibodies) and no development of de novo DSA was observed. Five episodes of rejection (2.9%) were observed within 12 months after vaccination, and only one patient had de novo anti‐HLA antibodies. The incidence of development of anti‐HLA antibodies after influenza vaccination in our cohort of SOT recipients was very low. Our findings indicate that influenza vaccination is safe and does not trigger humoral alloimmune responses in SOT recipients.     

Profiling non‐HLA antibody responses in antibody‐mediated rejection following heart transplantation

Antibody‐mediated rejection (AMR) driven by the development of donor‐specific antibodies (DSA) directed against mismatched donor human leukocyte antigen (HLA) is a major risk factor for graft loss in cardiac transplantation. Recently, the relevance of non‐HLA antibodies has become more prominent as AMR can be diagnosed in the absence of circulating DSA. Here, we assessed a single‐center cohort of 64 orthotopic heart transplant recipients transplanted between 1994 and 2014. Serum collected from patients with ≥ pAMR1 (n = 43) and non‐AMR (n = 21) were tested for reactivity against a panel of 44 non‐HLA autoantigens. The AMR group had a significantly greater percentage of patients with elevated reactivity to autoantigens compared to non‐AMR (P = .002) and healthy controls (n = 94, P < .0001). DSA‐positive AMR patients exhibited greater reactivity to autoantigens compared to DSA‐negative (P < .0001) and AMR patients with DSA and PRA > 10% were identified as the subgroup with significantly elevated responses. Reactivity to 4 antigens, vimentin, beta‐tubulin, lamin A/C, and apolipoprotein L2, was significantly different between AMR and non‐AMR patients. Moreover, increased reactivity to these antigens was associated with graft failure. These results suggest that antibodies to non‐HLA are associated with DSA‐positive AMR although their specific role in mediating allograft injury is not yet understood.     

Subclass analysis of donor HLA‐specific IgG in antibody‐incompatible renal transplantation reveals a significant association of IgG4 with rejection and graft failure

Donor HLA‐specific antibodies (DSAs) can cause rejection and graft loss after renal transplantation, but their levels measured by the current assays are not fully predictive of outcomes. We investigated whether IgG subclasses of DSA were associated with early rejection and graft failure. DSA levels were determined pretreatment, at the day of peak pan‐IgG level and at 30 days post‐transplantation in eighty HLA antibody‐incompatible kidney transplant recipients using a modified microbead assay. Pretreatment IgG₄ levels were predictive of acute antibody‐mediated rejection (P = 0.003) in the first 30 days post‐transplant. Pre‐treatment presence of IgG₄ DSA (P = 0.008) and day 30 IgG₃ DSA (P = 0.03) was associated with poor graft survival. Multivariate regression analysis showed that in addition to pan‐IgG levels, total IgG₄ levels were an independent risk factor for early rejection when measured pretreatment, and the presence of pretreatment IgG₄ DSA was also an independent risk factor for graft failure. Pretreatment IgG₄ DSA levels correlated independently with higher risk of early rejection episodes and medium‐term death‐censored graft survival. Thus, pretreatment IgG₄ DSA may be used as a biomarker to predict and risk stratify cases with higher levels of pan‐IgG DSA in HLA antibody‐incompatible transplantation. Further investigations are needed to confirm our results.     

Rethinking the advantage of zero‐HLA mismatches in unrelated living donor kidney transplantation: implications on kidney paired donation

The OPTN/UNOS Kidney Paired Donation (KPD) Pilot Program allocates priority to zero‐HLA mismatches. However, in unrelated living donor kidney transplants (LDKT)—the same donor source in KPD—no study has shown whether zero‐HLA mismatches provide any advantage over >0 HLA mismatches. We hypothesize that zero‐HLA mismatches among unrelated LDKT do not benefit graft survival. This retrospective SRTR database study analyzed LDKT recipients from 1987 to 2012. Among unrelated LDKT, subjects with zero‐HLA mismatches were compared to a 1:1–5 matched (by donor age ±1 year and year of transplantation) control cohort with >0 HLA mismatches. The primary endpoint was death‐censored graft survival. Among 32,654 unrelated LDKT recipients, 83 had zero‐HLA mismatches and were matched to 407 controls with >0 HLA mismatches. Kaplan–Meier analyses for death‐censored graft and patient survival showed no difference between study and control cohorts. In multivariate marginal Cox models, zero‐HLA mismatches saw no benefit with death‐censored graft survival (HR = 1.46, 95% CI 0.78–2.73) or patient survival (HR = 1.43, 95% CI 0.68–3.01). Our data suggest that in unrelated LDKT, zero‐HLA mismatches may not offer any survival advantage. Therefore, particular study of zero‐HLA mismatching is needed to validate its place in the OPTN/UNOS KPD Pilot Program allocation algorithm.     

Human leukocyte antigens antibodies after lung transplantation: Primary results of the HALT study

Donor‐specific antibodies (DSA) to mismatched human leukocyte antigens (HLA) are associated with worse outcomes after lung transplantation. To determine the incidence and characteristics of DSA early after lung transplantation, we conducted a prospective multicenter observational study that used standardized treatment and testing protocols. Among 119 transplant recipients, 43 (36%) developed DSA: 6 (14%) developed DSA only to class I HLA, 23 (53%) developed DSA only to class II HLA, and 14 (33%) developed DSA to both class I and class II HLA. The median DSA mean fluorescence intensity (MFI) was 3197. We identified a significant association between the Lung Allocation Score and the development of DSA (HR = 1.02, 95% CI: 1.001‐1.03, P = .047) and a significant association between DSA with an MFI ≥ 3000 and acute cellular rejection (ACR) grade ≥ A2 (HR = 2.11, 95% CI: 1.04‐4.27, P = .039). However, we did not detect an association between DSA and survival. We conclude that DSA occur frequently early after lung transplantation, and most target class II HLA. DSA with an MFI ≥ 3000 have a significant association with ACR. Extended follow‐up is necessary to determine the impact of DSA on other important outcomes.     

Effect of recipient gender and donor‐specific antibodies on antibody‐mediated rejection after heart transplantation

Gender‐difference regarding antibody‐mediated rejection (AMR) after heart transplantation has been described. However, no study accounted for the presence of preformed donor‐specific antibodies (pfDSA), a known risk factor of AMR, more common among women than men. In a single‐institution 6‐year cohort (2010‐2015), time to AMR was assessed, comparing men with women by survival analysis with a 1‐year death‐censored follow‐up. All AMRs were biopsy proven. Confounding variables that were accounted for included mean intensity fluorescence (MFI) of pfDSA, recipient age, HLA‐, size‐ and sex‐mismatch. 463 patients were included. Overall incidence of AMR was 10.3% at 1 year. After adjusting for confounding variables, independent risk factors of AMR were female recipient gender (adjusted hazard‐ratio [adj. HR] = 1.78 [1.06‐2.99]), P = .03) and the presence of pfDSA (adj. HR = 3.20 [1.80‐5.70], P < .001). This association remained significant when considering pfDSA by their MFI; female recipient gender had an adj. HR = 2.2 (P = .026) and MFI of pfDSA (per 1 MFI‐increase) adj. HR = 1.0002 (P < .0001). In this cohort, women were at higher risk of AMR than men and this risk increase was additive to that of pfDSA. These findings may suggest a gender‐related difference in the severity of pfDSA.     

Clinical outcomes of ABO‐ and HLA‐incompatible kidney transplantation: a nationwide cohort study

This was a nationwide cohort study to investigate the impact of anti‐A/B and donor‐specific anti‐HLA (HLA‐DSA) antibodies on the clinical outcomes in kidney transplant recipients (KTRs). We classified a total of 1964 KTRs into four groups: transplants from ABO‐incompatible donors (ABOi, n = 248); transplants in recipients with HLA‐DSA (HLAi, n = 144); transplants from combined ABOi and HLAi donors (ABOi + HLAi, n = 31); and a control group for whom neither ABOi nor HLAi was applicable (CONT, n = 1541). We compared the incidence of biopsy‐proven acute rejection (BPAR), allograft and patient survival rates. The incidence of BPAR was higher in the HLAi and ABOi + HLAi groups relative to the CONT group; in contrast, it was not higher in the ABOi group. Death‐censored graft survival rates did not differ across the four groups. However, relative to the CONT group, patient survival rate was reduced in the ABOi and ABOi + HLAi groups, and with infection being the most common cause of death. Further, multivariable analysis revealed that desensitization therapy because of ABOi or HLAi was independent risk factors for patient mortality. HLAi was a more important risk factor for BPAR compared with ABOi. However, pretransplant desensitization therapy for either ABOi or HLAi significantly increased the risk of infection‐related mortality.     

Clinical impact of preformed donor‐specific denatured class I HLA antibodies after kidney transplantation

Class I single‐antigen flow beads (SAFB) carry native and denatured human leukocyte antigen (HLA) molecules. Using a cohort of 179 class I HLA‐sensitized kidney recipients, we described incidence and clinical relevance of preformed denatured HLA donor‐specific antibodies (DSA) using two different assays: an acid‐treated SAFB assay (anti‐dHLA DSA) and the iBeads assays (SAFB+/iBeads‐ DSA). Eighty‐five class I DSA were found in 67 patients (median mean fluorescence intensity [MFI] of 1729 [range 520–13 882]). Anti‐dHLA and SAFB+/iBeads‐ DSA represented 11% and 18% of class I DSA and were mainly low MFI DSA (500–1000 MFI). Concordance between these two assays was good (90%). None of the patients with only class I anti‐dHLA DSA or only SAFB+/iBeads‐ DSA developed acute clinical antibody‐mediated rejection in the first‐year post‐transplantation, and their five‐yr death‐censored graft survival was similar to that of patients without DSA. Moreover, all these patients displayed a negative current T‐cell flow cytometry cross‐match. Therefore, both anti‐dHLA DSA and SAFB+/iBeads‐ DSA appear irrelevant, which could explain the good outcome observed in some patients with preformed class I DSA.     

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.