High Mean Fluorescence Intensity Donor‐Specific Anti‐HLA Antibodies Associated With Chronic Rejection Postliver Transplant

In contrast to kidney transplantation where donor‐specific anti‐HLA antibodies (DSA) negatively impact graft survival, correlation of DSA with clinical outcomes in patients after orthotopic liver transplantation (OLT) has not been clearly established. We hypothesized that DSA are present in patients who develop chronic rejection after OLT. Prospectively collected serial serum samples on 39 primary OLT patients with biopsy‐proven chronic rejection and 39 comparator patients were blinded and analyzed for DSA using LABScreen^® single antigen beads test, where a 1000 mean fluorescence value was considered positive. In study patients, the median graft survival was 15 months, 74% received ≥ one retransplant, 20% remain alive and 87% had ≥ one episode of acute rejection. This is in contrast to comparator patients where 69% remain alive, and no patient needed retransplant or experienced rejection. Thirty‐six chronic rejection patients (92%) and 24 (61%) comparator patients had DSA (p = 0.003). Chronic rejection versus comparator patients had higher mean fluorescence intensity (MFI) DSA. Although a further study with larger numbers of patients is needed to identify clinically significant thresholds, there is an association of high‐MFI DSA with chronic rejection after OLT.     

Effect of interleukin‐2 receptor antibody therapy on acute rejection risk and severity,long‐term renal function,infection and malignancy‐related mortality in renal transplant recipients

In renal transplantation, the use of interleukin‐2 receptor antibody (IL‐2Ra) has been associated with reduced rejection rates, but the effect of this agent on rejection severity and type, long‐term graft function and risk of infection and malignancy‐related mortality remains unclear. Using Australia and New Zealand Dialysis and Transplant Registry, all live‐ and deceased‐donor renal transplant recipients in Australia between 2000 and 2006 were included. Of the 3344 renal transplant recipients, 1874 (56.0%) received no induction and 1470 (44.0%) had received IL‐2Ra. Compared with no induction, IL‐2Ra was associated with reduced rejection risk (relative risk 0.70, 95% CI 0.60, 0.81) and higher estimated glomerular filtration rate at 5 years (difference in means 3.51, 95% CI 0.83, 6.19). Severity and type of rejection were similar in both the groups. The adjusted rate of death attributed to malignancy for no induction and IL‐2Ra per 1000 patient‐years was 1.48 and 1.63, respectively, whereas death attributed to infection was 2.42 and 2.16 respectively. This registry analysis demonstrates that IL‐2Ra induction in kidney transplantation is associated with substantial clinical benefits of reduced risk of acute rejection and improved long‐term graft function without an increase in adverse events.     

Isolated v‐lesion represents a benign phenotype of vascular rejection of the kidney allograft – a retrospective study

While the detrimental impact of the humoral acute vascular rejection (AVR) phenotype is recognized, the prognostic significance of isolated v‐lesion (IV) remains unclear. In this retrospective single‐centre study, AVR was found in 98 of 1015 patients (9.7%) who had undergone kidney transplantation in 2010–2014, with donor‐specific antibodies (DSA) evaluated in all of them. The outcome of four AVR phenotypes was evaluated during median follow‐up of 59 months; in 25 patients with IV, 18 with T‐cell‐mediated vascular rejection (TCMVR), 19 with antibody‐mediated vascular rejection (AMVR) and 36 with suspected antibody‐mediated rejection (sAMVR). AVR was diagnosed mainly by for‐cause biopsy (81%) early after transplantation (median 19 POD) and appeared as mild‐grade intimal arteritis. IV occurred in low‐sensitized patients after the first transplantation (96%) in the absence of DSA. IV responded satisfactorily to treatment (88%), showed no persistence of rejection in surveillance biopsy, and had stable graft function, minimal proteinuria and excellent DCGS (96%). Contrary to that, Kaplan–Meier estimate of 3‐year DCGS of AMVR was 66% (log‐rank = 0.0004). Early IV represents a benign phenotype of AVR with a favourable outcome. This study prompts further research to evaluate the nature of IV before considering any change in the classification and management.     

Rejection of Cardiac Xenografts Transplanted from α1,3‐Galactosyltransferase Gene‐Knockout (GalT‐KO) Pigs to Baboons

The use of α1,3‐galactosyltransferase gene‐knockout (GalT‐KO) swine donors in discordant xenotransplantation has extended the survival of cardiac xenografts in baboons following transplantation. Eight baboons received heterotopic cardiac xenografts from GalT‐KO swine and were treated with a chronic immunosuppressive regimen. The pathologic features of acute humoral xenograft rejection (AHXR), acute cellular xenograft rejection (ACXR) and chronic rejection were assessed in the grafts. No hyperacute rejection developed and one graft survived up to 6 months after transplantation. However, all GalT‐KO heart grafts underwent graft failure with AHXR, ACXR and/or chronic rejection. AHXR was characterized by interstitial hemorrhage and multiple thrombi in vessels of various sizes. ACXR was characterized by TUNEL⁺ graft cell injury with the infiltration of T cells (including CD3 and TIA‐1⁺ cytotoxic T cells), CD4⁺ cells, CD8⁺ cells, macrophages and a small number of B and NK cells. Chronic xenograft vasculopathy, a manifestation of chronic rejection, was characterized by arterial intimal thickening with TUNEL⁺ dead cells, antibody and complement deposition, and/or cytotoxic T‐cell infiltration. In conclusion, despite the absence of the Gal epitope, acute and chronic antibody and cell‐mediated rejection developed in grafts, maintained by chronic immunosupression, presumably due to de novo responses to non‐Gal antigens.     

Role of heme oxygenase‐1 in transplantation

Heme oxygenase‐1 (HO‐1) is the rate‐limiting enzyme in heme catabolism that converts heme to Fe++, carbon monoxide and biliverdin. HO‐1 acts anti‐inflammatory and modulates apoptosis in many pathological conditions. In transplantation, HO‐1 is overexpressed in organs during brain death, when undergoing ischemic damage and rejection. However, intentionally induced, it ameliorates pathological processes like ischemia reperfusion injury, allograft, xenograft or islet rejection, facilitates donor specific tolerance and alleviates chronic allograft changes. We herein consistently summarize the huge amount of data on HO‐1 and transplantation that have been generated in multiple laboratories during the last 15 years and suggest possible clinical implications and applications for the near future.     

Redo living‐donor lobar lung transplantation for bronchiolitis obliterans associated with antibody‐mediated rejection

Living‐donor lobar lung transplantation (LDLLT) is an established therapy for patients with end‐stage lung disease, but living‐donor lobar lung retransplantation (re‐LDLLT) is rarely reported. We previously reported a case of unilateral antibody‐mediated rejection after LDLLT in the presence of newly formed donor‐specific antibodies against a right‐lobe donor. The same patient developed contralateral bronchiolitis obliterans, resulting in bilateral bronchiolitis obliterans, but re‐LDLLT was successful. Pathological findings of the explanted lungs were consistent with the clinical course of the patient. One year after re‐LDLLT, the patient is doing well without any anti‐human leukocyte antigen antibodies. Four lobes from four different donors were transplanted in this patient. The first two lobes were rejected eventually, but the two lobes implanted later presented no signs of rejection at least for 1 year after the transplant. Herein, we report this rare case and compare the clinical course and pathological findings.     

Non‐organ‐specific and anti‐endothelial antibodies in relation to CMV infection and acute rejection in renal transplant recipients

Costa C, Touscoz GA, Bergallo M, Terlizzi ME, Astegiano S, Sidoti F, Sinesi F, Segoloni GP, Cavallo R. Non‐organ‐specific and anti‐endothelial antibodies in relation to CMV infection and acute rejection in renal transplant recipients.
Clin Transplant 2010: 24: 488–492.
© 2009 John Wiley & Sons A/S. Abstract: The presence of non‐organ‐specific (NOSA) and anti‐endothelial antibodies (AECAs) and the onset of rejection in relation to cytomegalovirus (CMV) infection was investigated in 96 renal transplant recipients: 48 CMV pp65‐antigenemia‐negative (group 1) and 48 positive (group 2). The presence of autoantibodies (autoAbs) was evaluated before and following renal transplantation (first three months) by indirect immunofluoresce. Before transplantation, none of the patients was positive to AECAs, while eight (8.3%) were positive to NOSAs. Post‐transplantation, AECA were found in none of patients from group 1 vs. 15/48 (31.2%) from group 2 (p < 0.05); NOSAs were detected in 9/48 (18.8%) and 9/48 patients from group 1 and 2, respectively. An acute rejection was diagnosed in ten cases: six of interstitial type (antigenemia‐, and AECA‐negative; two NOSA‐positive); four of vascular type (all of them NOSA‐negative, 3/4 antigenemia‐, and AECA‐positive). CMV infection did not seem to be significantly associated with the appearance of NOSAs, while there was a significant correlation with the occurrence of AECAs. No significant correlation was found between acute rejection and the occurrence of NOSAs, while 75% of the cases of vascular rejection was associated to CMV infection and AECA‐positivity, suggesting the pathogenic role of CMV‐mediated endothelial damage.     

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.     

Incidence,characterization, and impact of newly detected donor‐specific anti‐HLA antibody in the first year after pediatric heart transplantation: A report from the CTOTC‐04 study

Data on the clinical importance of newly detected donor‐specific anti‐HLA antibodies (ndDSAs) after pediatric heart transplantation are lacking despite mounting evidence of the detrimental effect of de novo DSAs in solid organ transplantation. We prospectively tested 237 pediatric heart transplant recipients for ndDSAs in the first year posttransplantation to determine their incidence, pattern, and clinical impact. One‐third of patients developed ndDSAs; when present, these were mostly detected within the first 6 weeks after transplantation, suggesting that memory responses may predominate over true de novo DSA production in this population. In the absence of preexisting DSAs, patients with ndDSAs had significantly more acute cellular rejection but not antibody‐mediated rejection, and there was no impact on graft and patient survival in the first year posttransplantation. Risk factors for ndDSAs included common sensitizing events. Given the early detection of the antibody response, memory responses may be more important in the first year after pediatric heart transplantation and patients with a history of a sensitizing event may be at risk even with a negative pretransplantation antibody screen. The impact on late graft and patient outcomes of first‐year ndDSAs is being assessed in an extended cohort of patients.     

Codominant Role of Interferon‐γ– and Interleukin‐17–Producing T Cells During Rejection in Full Facial Transplant Recipients

Facial transplantation is a life‐changing procedure for patients with severe composite facial defects. However, skin is the most immunogenic of all transplants, and better understanding of the immunological processes after facial transplantation is of paramount importance. Here, we describe six patients who underwent full facial transplantation at our institution, with a mean follow‐up of 2.7 years. Seum, peripheral blood mononuclear cells, and skin biopsy specimens were collected prospectively, and a detailed characterization of their immune response (51 time points) was performed, defining 47 immune cell subsets, 24 serum cytokines, anti‐HLA antibodies, and donor alloreactivity on each sample, producing 4269 data points. In a nonrejecting state, patients had a predominant T helper 2 cell phenotype in the blood. All patients developed at least one episode of acute cellular rejection, which was characterized by increases in interferon‐γ/interleukin‐17–producing cells in peripheral blood and in the allograft's skin. Serum monocyte chemotactic protein‐1 level was significantly increased during rejection compared with prerejection time points. None of the patients developed de novo donor‐specific antibodies, despite a fourfold expansion in T follicular helper cells at 1 year posttransplantation. In sum, facial transplantation is frequently complicated by a codominant interferon‐γ/interleukin‐17–mediated acute cellular rejection process. Despite that, medium‐term outcomes are promising with no evidence of de novo donor‐specific antibody development.     

Postoperative rebound of antiblood type antibodies and antibody‐mediated rejection after ABO‐incompatible living‐related kidney transplantation

The purpose of this study is to examine whether postoperative antiblood type antibody rebound is attributed to kidney allograft rejection in ABO blood type‐incompatible (ABO‐I) living‐related kidney transplantation (KTx). A total of 191 ABO‐I recipients who received ABO‐I living‐related KTx between 2001 and 2013 were divided into two groups: Group 1 consisted of low rebound [(≦1:32), N = 170] and Group 2 consisted of high rebound [(≧1:64), N = 21], according to the levels of the rebounded antiblood type antibodies within 1 year after transplantation. No prophylactic treatment for rejection was administered for elevated antiblood type antibodies, regardless of the levels of the rebounded antibodies. Within 1 year after transplantation, T‐cell‐mediated rejection was observed in 13 of 170 recipients (13/170, 8%) in Group 1 and in 2 of 21 recipients (2/21, 10%) in Group 2 (Groups 1 vs. 2, P = 0.432). Antibody‐mediated rejection was observed in 15 of 170 recipients (15/170, 9%) and 2 of 21 recipients (2/21, 10%) in Groups 1 and 2, respectively (P = 0.898). In this study, we found no correlation between the postoperative antiblood type antibody rebound and the incidence of acute rejection. We concluded that no treatment is necessary for rebounded antiblood type antibodies.     

Circulating pig‐specific DNA as a novel biomarker for monitoring xenograft rejection

Monitoring for immune rejection is crucial for long‐term survival of pig xenografts. Circulating DNA is a promising non‐invasive biomarker for either organ injury or response to therapy. In this study, circulating pig‐specific DNA (cpsDNA) was monitored during xenograft rejection. Potential targets of cpsDNA were selected by in silico analysis, and species specificity of selected primers was confirmed by PCR. Subsequently, cpsDNA as a biomarker was evaluated using a complement‐dependent cytotoxicity (CDC) assay in vitro. Then, early diagnosis and response to rapamycin were assessed by an in vivo imaging model of pig‐to‐mouse cell transplantation. Finally, cpsDNA was monitored in a pig‐to‐monkey artery patch transplantation model. The results showed that (a) a method of cpsDNA quantitation was established for application in mouse and nonhuman primate models; (b) cpsDNA reflected CDC in vitro; (c) cpsDNA in vivo mirrored xenograft rejection, and correlated with xenograft loss in pig‐to‐mouse cell transplantation; (d) cpsDNA was significantly reduced when rapamycin was administered; and (e) dynamic cpsDNA was detectable in pig‐to‐monkey artery patch transplantation. In conclusion, measurement of cpsDNA could prove to be a less invasive, but more specific and sensitive low‐cost biomarker enabling monitoring of xenograft rejection and the response to immunosuppressive therapy.     

Anti‐HLA Donor‐Specific Antibodies Detected in Positive B‐Cell Crossmatches by Luminex® Predict Late Graft Loss

The significance of B‐cell crossmatching in kidney transplantation is controversial. Recipients (n = 471) transplanted in a single centre from 1987 to 2005 with complete T‐ and B‐cell crossmatch records were studied. Sera from 83 patients transplanted across a positive B‐cell crossmatch, with concomitant negative T‐cell crossmatch (T–B+) on either current and/or peak sera were studied using Luminex^® to determine presence of donor‐specific antibodies (DSA). Clinical outcomes of T–B+ patients were compared with 386 T–B? patients. T–B+ predicted vascular (p = 0.01), but not cellular (p = 0.82) or glomerular (p = 0.14) rejection. IgG HLA DSA were found in 33% (n = 27) of the T–B+ patients and were associated with higher risk of any (p = 0.047), vascular (p = 0.01) or glomerular (p < 0.001) rejection at 6 months. Of 27 patients with DSA, 18/21 (86%) were the complement‐fixing IgG₁ and/or IgG₃ subclass antibodies. DSA imposed a statistically significant higher risk of graft loss 5 years posttransplant (1.8 [1.0–3.3], p = 0.045). This study showed that only one‐third of positive B‐cell crossmatch (BXM) was caused by DSA and was associated with late graft loss. Thus, using BXM to preclude kidney transplantation may potentially disadvantage >60% of patients in whom BXM is not indicative of the presence of DSA.     

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.     

Equivalent Outcomes for Pediatric Heart Transplantation Recipients: ABO‐Blood Group Incompatible versus ABO‐Compatible

ABO‐blood group incompatible infant heart transplantation has had excellent short‐term outcomes. Uncertainties about long‐term outcomes have been a barrier to the adoption of this strategy worldwide. We report a nonrandomized comparison of clinical outcomes over 10 years of the largest cohort of ABO‐incompatible recipients. ABO‐incompatible (n = 35) and ABO‐compatible (n = 45) infant heart transplantation recipients (≤14 months old, 1996–2006) showed no important differences in pretransplantation characteristics. There was no difference in incidence of and time to moderate acute cellular rejection. Despite either the presence (seven patients) or development (eight patients) of donor‐specific antibodies against blood group antigens, in only two ABO‐incompatible patients were these antibodies implicated in antibody‐mediated rejection (which occurred early posttransplantation, was easily managed and did not recur in follow‐up). Occurrence of graft vasculopathy (11%), malignancy (11%) and freedom from severe renal dysfunction were identical in both groups. Survival was identical (74% at 7 years posttransplantation). ABO‐blood group incompatible heart transplantation has excellent outcomes that are indistinguishable from those of the ABO‐compatible population and there is no clinical justification for withholding this lifesaving strategy from all infants listed for heart transplantation. Further studies into observed differing responses in the development of donor‐specific isohemagglutinins and the implications for graft accommodation are warranted.     

De novo donor‐specific HLA antibodies after combined intestinal and vascularized composite allotransplantation — a retrospective study

Combining vascularized composite allotransplantation (VCA) with intestinal transplantation to achieve primary abdominal closure has become a feasible procedure. Besides facilitating closure, the abdominal wall can be used to monitor intestinal rejection. As the inclusion of a VCA raises the possibility of an enhanced alloimmune response, we investigated the incidence and clinical effect of de novo donor‐specific HLA antibodies (dnDSA) in a cohort of patients receiving an intestinal transplant with or without a VCA. The sequential clinical study includes 32 recipients of deceased donor intestinal and VCA transplants performed between 2008 and 2015; eight (25%) modified multivisceral transplants and 24 (75%) isolated small bowel transplants. A VCA was used in 18 (56.3%) cases. There were no episodes of intestinal rejection without VCA rejection. Fourteen patients (14 of 29; 48.3%) developed dnDSA. In the VCA group, fewer patients developed dnDSA; six of 16 (37.5%) VCA vs. eight of 13 (61.5%) non‐VCA. There was no statistically significant difference in one‐ and 3‐year overall graft survival stratified for the presence of dnDSA; P = 0.286. In the study, there is no evidence that the addition of a VCA increases the incidence of dnDSA formation compared to transplantation of the intestine alone.     

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.     

Preserved Endocrine Function in a Pancreas Transplant Recipient with Pancreatic Panniculitis and Antibody‐Mediated Rejection

Pancreas transplantation is an effective treatment option for patients with complicated diabetes mellitus. Pancreas allograft recipients are followed with laboratory markers such as serum amylase, lipase and glucose levels. Hyperglycemia may indicate severe acute rejection and has recently been associated with antibody‐mediated (humoral) rejection. In this report, we describe a unique case of a pancreas‐after‐kidney (PAK) transplant recipient with the rare presentation of pancreatic panniculitis, biopsy‐proven severe acute cellular and antibody‐mediated pancreas allograft rejection and surprisingly well‐preserved endocrine function despite treatment with high dose steroids. We discuss the clinicopathologic features of antibody‐mediated pancreas rejection, including the importance of correlating pancreas allograft biopsy, C4d staining and donor specific antibodies, to diagnose antibody‐mediated rejection and initiate the correct treatment.     

Bortezomib for Acute Antibody‐Mediated Rejection in Liver Transplantation

Antibody‐mediated rejection (AMR) is an uncommon, but challenging type of rejection after solid organ transplantation. We review three cases of AMR in ABO‐compatible liver transplant recipients. These cases were characterized by severe acute rejection resistant to steroids and antithymocyte globulin, histologic evidence of plasma cell infiltrates, C4d positivity and high serum anti‐HLA donor‐specific antibodies. All three patients were treated with bortezomib, a proteasome inhibitor effective in depleting plasma cells. After treatment, all patients had improved or normal liver function tests, resolution of C4d deposition and significant decline in their HLA donor‐specific antibodies.     

Use of tacrolimus and mycophenolate mofetil as induction and maintenance in simultaneous pancreas‐kidney transplantation

Abstract Clinical trials using quadruple immunosuppression that include the combination of tacrolimus and mycophenolate mofetil have been shown to reduce the incidence of acute rejection episodes in simultaneous pancreas‐kidney (SPK) transplantation. In an attempt to obtain a low rejection rate without antibody induction therapy, we undertook a prospective study of combined tacrolimus and mycophenolate mofetil and steroids as primary immunosuppression for SPK transplantation. In this study, we analyzed 17 patients who received low‐dose intravenous tacrolimus as induction therapy. This was combined with oral tacrolimus, mycophenolate mofetil, and steroids as the primary immunosuppression regimen. There was a significant reduction of empirically and biopsy‐proven rejection with an incidence of 23 % (4 patients). Leukopenia, gastroparesis, and gastrointestinal side‐effects were the cause of discontinuation of mycophenolate mofetil, or low tacrolimus trough level in those patients who developed rejection. All rejection episodes were easy to treat, and none of them required antibody therapy. The combination of tacrolimus with mycophenolate mofetil without antibody induction therapy is effective in preventing early acute rejection. This combination is safe and effective as an alternative immunosuppressive regimen after SPK transplantation.