Presence Of Donor-specific anti-HLA Antibodies Research Articles

#2239 Identification of non-HLA antibodies associated with the development of antibody-mediated damage after kidney transplantation

Abstract Background and Aims Non-HLA antibodies may play a role in the development of antibody-mediated rejection (ABMR) in the presence of donor-specific anti-HLA antibodies (HLA-DSA) or microvascular inflammation (MVI) without HLA-DSA in kidney transplantation (KT). The development of multiplex panels allowed the analysis of multiple antibodies simultaneously and new antibodies potentially related to ABMR/MVI have been identified. Method Retrospective study of a cohort of 169 KT recipients with: a) pre- and post-KT sera; b) follow-up HLA antibody monitoring; and c) follow-up biopsies. We determined the presence of 60 non-HLA antibodies in sera using a multiplex test: the Single Non-HLA Beads kit (LIFECODES®) suitable for the SAB assay performed using Luminex® technology. Results Pre-KT, we detected non-HLA antibodies in 85% of the recipients, with a median of 3 (2-5) positive antibodies. During follow-up, 73 patients developed ABMR/MVI. Pre-KT, in a univariate analysis including the presence of HLA-DSA (8.3% in the cohort) we detected 7 antibodies individually associated with ABMR/MVI. In multivariate analysis (Figure) GSTT1, NCL, PLA2R1 and Thyroglobulin antibodies together with HLA DSA were significantly associated with the development of ABMR/MVI, although only GSST1 and Thyroglobulin appear in a relevant number of patients (>10 patients) involved in 32 cases of ABMR and 6 cases of MVI. Post-KT, only the detection of anti-GSTT1 antibodies in sera 1- and 3-years post-TR was associated with ABMR/MVI in 3-year biopsies. Conclusion Pre-KT the detection of antibodies against GSST1 and Thyroglobulin using a multiplex non-HLA antibody detection panel is independently associated with the development of ABMR/MVI during follow-up. Post-KT detection of GSST1 is also associated with ABMR/MVI in 3-year biopsies.

Impact of Immunosuppression Intensified Conditioning Regimen for Patients with Strong Positive Pre-Transplantation Donor Specific Anti-HLA Antibodies (DSAs) Undergoing Haploidentical Hematopoietic Stem Cell Transplantation

Objective: Immunosuppression intensified conditioning regimen has been applied for 10 patients with strong positive pre-transplantation Donor specific Anti-HLA Antibodies (DSAs) undergoing Haploidentical Hematopoietic Stem Cell Transplantation (HSCT), its effects on engraftment of hematopoietic stem cell were examined. Methods: Characteristics of 10 consecutive patients with strong positive pre-transplantation DSAs were retrospectively analyzed, including gender, age, diagnosis, disease status pre-transplantation, presence of DSA, conditioning regimens, engraftment, graft versus host disease (GVHD) incidence and survival. Results: Ten patients [3 males vs 7 females, median age 53.5(36-64)] received immunosuppression intensified conditioning regimen: Fludarabine plus busulfan (FluBu) combining total body irradiation and cyclophosphamide (TBI-Cy). DSA levels gradually decreased in all patients after preparative conditioning, and the mean fluorescence intensity (MFI) values dropped significantly (P＜0.003). The average MFI values dropped 40% at day 7 post-HSCT, 8 cases acquired hematopoietic reconstitution, the median time of neutrophil engraftment was 15.6(10-16) days, and 19(13-22) days for platelet engraftment. One case had primary graft failure and another one had poor graft function. After a median follow-up of 12.5(1.5-27) months, 7 cases remained in disease remission state with negative DSA assay, including 2 cases with MFI values higher than 20000 pre-transplantation. Conclusions：Immunosuppression intensified conditioning regimen can efficiently decrease the Donor specific Anti-HLA Antibodies (DSA) level, which leads to lowered chances of primary graft failure.

Rapid desensitization through immunoadsorption during cardiopulmonary bypass. A novel method to facilitate human leukocyte antigen incompatible heart transplantation.

Anti-human leukocyte antigen (HLA)-antibody production represents a major barrier to heart transplantation, limiting recipient compatibility with potential donors and increasing the risk of complications with poor waiting-list outcomes. Currently there is no consensus to when desensitization should take place, and through what mechanism, meaning that sensitized patients must wait for a compatible donor for many months, if not years. We aimed to determine if intraoperative immunoadsorption could provide a potential desensitization methodology. Anti-HLA antibody-containing whole blood was added to a Cardiopulmonary bypass (CPB) circuit set up to mimic a 20kg patient undergoing heart transplantation. Plasma was separated and diverted to a standalone, secondary immunoadsorption system, with antibody-depleted plasma returned to the CPB circuit. Samples for anti-HLA antibody definition were taken at baseline, when combined with the CPB prime (on bypass), and then every 20min for the duration of treatment (total 180min). A reduction in individual allele median fluorescence intensity (MFI) to below clinically relevant levels (<1000 MFI), and in the majority of cases below the lower positive detection limit (<500 MFI), even in alleles with a baseline MFI >4000 was demonstrated. Reduction occurred in all cases within 120min, demonstrating efficacy in a time period usual for heart transplantation. Flowcytometric crossmatching of suitable pseudo-donor lymphocytes demonstrated a change from T cell and B cell positive channel shifts to negative, demonstrating a reduction in binding capacity. Intraoperative immunoadsorption in an ex vivo setting demonstrates clinically relevant reductions in anti-HLA antibodies within the normal timeframe for heart transplantation. This method represents a potential desensitization technique that could enable sensitized children to accept a donor organ earlier, even in the presence of donor-specific anti-HLA antibodies.

Presence of antibodies against HLA class I and class II molecules in children before and after allo-HSCT. Alloantibodies before and after HSCT.

A severe complication of allogeneic hematopoietic stem cell transplantation (HSCT) is graft failure (GF). Among others, donor-specific anti-HLA antibodies (DSA) are associated with graft rejection after allogeneic or haploidentical transplantation in adults. Knowledge of DSA and pediatric recipients is limited. Hence, we aimed to generate more information about the presence of DSA (pre- and post-HSCT) and the clinical outcomes (graft rejection and poor function) in children. We identified DSA in 27% of the patients. We observed a higher frequency (50%) of DSA-bearing patients with a benign disease diagnosis than those diagnosed with leukemia (16.66%). We observed graft rejection in one patient (with DSA against two alleles of HLA class I molecules) and poor function in three recipients during the first 30 days after HSCT in the absence of DSA. The presence of donor and nondonor HLA-specific antibodies decreased substantially after transplantation. After the transplant, we identified two patients with DSA specific for HLA class I molecules (independent of clinical relevance), and four recipients showed PGF in the absence of DSA. We were unable to establish any association between the presence of DSA and a clinical outcome: graft failure or prevalence of viral infection.

Haploidentical stem cell transplantation for patients with sickle cell disease: current status

For patients with high-risk sickle cell disease (SCD) without any available matched sibling or unrelated donor, haploidentical stem cell transplantation (haploHCT) expands the availability of this life-saving intervention to nearly all patients who may benefit from HCT. The greatest challenge in haploHCT has been the significant risk of graft failure. Developing a treatment modality which sustains engraftment without increasing the incidence of debilitating graft-versus-host disease (GvHD) remains the ultimate goal. A number of modifications have been explored to overcome the high incidence of graft rejection and severe GvHD including: (1) ex-vivo T-cell depletion (via CD34+ selection, CD3+/CD19+, or TCRαβ+/CD19+ depletion), and (2) in vivo T-cell depletion using unmanipulated grafts followed by post-transplant cyclophosphamide (PTCy) for GvHD prophylaxis. Furthermore, the presence of donor-specific anti-HLA antibodies (DSA) has been associated with an increased risk of both graft failure and poor graft function. Several approaches for desensitization ameliorate this risk when a suitable donor without DSA is not available. In addition to advances in supportive care, the recent demonstration that stable mixed chimerism post-HCT sufficiently sustains symptom-free status has opened the door for less toxic treatment approaches yielding excellent survival outcomes. Though late effects remain uncertain, the goal of finding the least toxic conditioning regimen while providing the highest rate of donor engraftment draws closer within reach. In this review, the authors aim to present the latest findings, challenges, and treatment modalities of this life-saving modality.

Antigen and Cell-Based Assays for the Detection of Non-HLA Antibodies.

To date, human leukocyte antigens (HLA) have been the major focus in the approach to acute and chronic antibody-mediated rejection (AMBR) in solid-organ transplantation. However, evidence from the clinic and published studies has shown that non-HLA antibodies, particularly anti-endothelial cell antibodies (AECAs), are found either in the context of AMBR or synergistically in the presence of donor-specific anti-HLA antibodies (DSA). Numerous studies have explored the influence of AECAs on clinical outcomes, yet the determination of the exact clinical relevance of non-HLA antibodies in organ transplantation is not fully established. This is due to highly heterogeneous study designs including differences in testing methods and outcome measures. Efforts to develop reliable and sensitive diagnostic non-HLA antibody tests are continuously made. This is essential considering the technical difficulties of non-HLA antibody assays and the large variation in reported incidences of antibodies. In addition, it is important to take donor specificity into account in order to draw clinically relevant conclusions from non-HLA antibody assays. Here, we provide an overview of non-HLA solid-phase and cell-based crossmatch assays for use in solid-organ transplantation that are currently available, either in a research setting or commercially.

Anti-HLA immunization of patients qualified for lung transplantation – Single center study

For lung transplantation, the presence of donor-specific anti-HLA antibodies (DSA) is an important factor of antibody-mediated rejection (AMR) in its hyperacute, acute or chronic form during long-term follow up. The aim of the study was to assess the allosensitization of Polish patients qualified for a lung transplantation in our center.A retrospective study of 161 potential lung allograft recipients, also of 31 patients transplanted in the University Hospital of Gdansk, between June 2018 and December 2020 were performed.121 potential recipients were thoroughly tested for immunization status before eventual lung transplantation. SAB-testing, PRA-CDC and vPRA assessment, and HLA typing were performed to guide donor-recipient matching and risk stratification. Then 73 patients were separated and qualified for the list of patients awaiting lung transplantation. Then 31 patients were transplanted based on a negative biological crossmatch result.The patients were generally not sensitized, as the median PRA-CDC was 0% (min 0; max 53), and the vPRA, calculated according to HLA ABDR (>2000 cut-off MFI), was 8% (min 0; max 99). If the cut-off was split into 2000 MFI for HLA ABDR, 10,000 MFI for HLAC, and 7000 MFI for HLA-DQ, the vPRA increased to 20% (min 0; max 99). The immunization status was assessed with single antigen-SAB assays. For class I, the number of any detectable alloantibodies was 14 (11.6%) 21 (17.35%) 16 (13.22%) for locus HLA-A/B/C, and 28 (23.14%) 30 (24.8%) 24 (19.8%) for locus HLA-DR/DQ/DP, respectively. The immunization of the transplanted patients was then analyzed in detail.Summarizing, the study is an analysis of the degree of anti-HLA immunization in the population of patients eligible for lung transplantation, which showed that this degree is of low intensity and can be effectively and safely and very precisely diagnosed before transplantation.

Increased Levels of sCD30 Have No Impact on the Incidence of Early ABMR and Long-Term Outcome in Intermediate-Risk Renal Transplant Patients With Preformed DSA.

Background: It is still incompletely understood why some patients with preformed donor-specific anti-HLA antibodies (DSA) have reduced kidney allograft survival secondary to antibody-mediated rejection (ABMR), whereas many DSA-positive patients have favorable long-term outcomes. Elevated levels of soluble CD30 (sCD30) have emerged as a promising biomarker indicating deleterious T-cell help in conjunction with DSA in immunologically high-risk patients. We hypothesized that this would also be true in intermediate-risk patients.Methods: We retrospectively analyzed pre-transplant sera from 287 CDC-crossmatch negative patients treated with basiliximab induction and tacrolimus-based maintenance therapy for the presence of DSA and sCD30. The incidence of ABMR according to the Banff 2019 classification and death-censored allograft survival were determined.Results: During a median follow-up of 7.4 years, allograft survival was significantly lower in DSA-positive as compared to DSA-negative patients (p < 0.001). In DSA-positive patients, most pronounced in those with strong DSA (MFI > 5,000), increased levels of sCD30 were associated with accelerated graft loss compared to patients with low sCD30 (3-year allograft survival 75 vs. 95%). Long-term survival, however, was comparable in DSA-positive patients irrespective of sCD30 status. Likewise, the incidence of early ABMR and lesion score characteristics were comparable between sCD30-positive and sCD30-negative patients with DSA. Finally, increased sCD30 levels were not predictive for early persistence of DSA.Conclusion: Preformed DSA are associated with an increased risk for ABMR and long-term graft loss independent of sCD30 levels in intermediate-risk kidney transplant patients.

Donor HLA genotyping of ex vivo expanded urine cells from kidney transplant recipients.

Antibody-mediated rejection (AMR) induced by donor-specific anti-HLA antibodies (DSA) remains a major cause of long-term graft loss after kidney transplantation. Currently, the presence of DSA cannot always be determined at a specific allele level, because existing donor HLA typing is low resolution and often incomplete, lacking HLA-DP, and occasionally HLA-C and HLA-DQ information and historical donor DNA samples are not available for HLA retyping. Here we present a novel, non-invasive technique for obtaining donor DNA from selectively expanded donor cells from urine of renal transplant recipients. Urine-derived cells were successfully expanded ex vivo from 31 of 32 enrolled renal transplant recipients, and with DNA obtained from these cells, donor HLA typing was unambiguously determined for HLA-A, -B, -C, -DRB1, -DQA1, -DQB1, -DPA1 and -DPB1 loci by next-generation sequencing. Our results showed 100% concordance of HLA typing data between donor peripheral blood and recipient urine-derived cells. In comparison, HLA typing showed that DNA derived from urine sediments mainly contained recipient-derived DNA. We also present the successful application of our novel technique in a clinical case of AMR in a renal transplant recipient. Urine-derived donor cells can be isolated from kidney transplant recipients and serve as a suitable source of donor material for reliable high-resolution HLA genotyping. Thus, this approach can aid the assessment of DSA specificity to support the diagnosis of AMR as well as the evaluation of treatment efficacy in kidney transplant recipients when complete donor HLA information and donor DNA are unavailable.

CLINICAL SIGNIFICANCE OF LATE ANTIBODY-MEDIATED REJECTION WITHOUT DONOR-SPECIFIC ANTI-HLA ANTIBODIES

Background: Late onset antibody-mediated rejection (AMR) is a leading cause of kidney allograft failure. Its diagnosis has been based on a combination of morphologic, immunohistologic findings, and presence of donor-specific anti-HLA antibodies (DSA). Although the presence of DSA is no longer required for AMR diagnosis according to Banff 2017 classification, the clinical significance of late onset AMR without DSA remains unclear. Here we compared clinical outcomes of late onset AMR with and without DSA. Methods: We analyzed 126 cases of late AMR (> 6 months after transplant) that meet the Banff 2017 histologic criteria for AMR. All cases were diagnosed by for cause biopsy and grouped into DSA-positive (n=103) and DSA-negative (n=23) AMR groups. The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. Results: The histological picture did not differ between DSA-negative and DSA-positive AMR, with the exception of increased level of peritubular capillaritis in DSA-positive AMR. Median time from transplant to AMR diagnosis was 80 months (IQR, 39-118). At the time of AMR diagnosis, both groups had similar graft function (36.3 ± 16.0 for DSA-negative and 39.7 ± 20.2mL/min/1.73 m2 for DSA-positive AMR, P=0.408). Mean eGFR after AMR were similar irrespective of the presence of DSA. There were 28 (26.2%) graft failures in the DSA-negative and 8 (27.6%) graft failures in the DSA-positive AMR groups, which was not statistically different (P=0.950). Conclusion: In late onset AMR, there was no significant difference between AMR with and without DSA in clinical outcomes.

Unmanipulated haploidentical transplantation for adult patients with hematological malignancies.

Unmanipulated haploidentical transplantation for adult patients with hematological malignancies.

Donor-Specific Anti-HLA Antibodies in Haploidentical Stem Cell Transplantation with Post-Transplantation Cyclophosphamide: Risk of Graft Failure, Poor Graft Function, and Impact on Outcomes.

The presence of donor-specific anti-HLA antibodies (DSA) is associated with a 10-fold increased risk of graft failure in haploidentical stem cell transplantation (haplo-SCT). Consensus guidelines from the European Society for Blood and Marrow Transplantation set a mean fluorescence intensity (MFI) >1000 as a cutoff for DSA positivity. In the absence of an alternative donor, it is recommended that patients undergo desensitization therapy, especially with high DSA levels (>5000 MFI). The aim of this study was to analyze the impact of DSA on risk of graft failure and poor graft function, as well as on major outcomes in a consecutive cohort of patients who were systematically screened for DSA before haplo-SCT. A total of 141 consecutive patients were candidates for unmanipulated haplo-SCT with post-transplantation cyclophosphamide (PT-Cy) at our center between January 2012 and January 2018, and 135 were analyzed for the presence of HLA antibodies. Of these 134 patients underwent haplo-SCT. HLA antibodies were detected in 40 patients, including 19 with DSA and 21 without DSA. Ten of the 19 patients with DSA underwent transplantation using that donor, whereas 2 underwent a desensitization program before transplantation. Only 2 patients experienced primary graft failure (1.4 %), both of whom were without DSA. Twenty patients developed a poor graft function (15%). The 3-year overall survival (OS), 3-year progression-free survival (PFS), and 1-year nonrelapse mortality (NRM) were analyzed according to the presence or absence of DSA. No statistically significant difference was found. No impact of the presence of DSA on the risk of developing graft failure and poor graft function was revealed. Major outcomes of transplantation were analyzed separately in patients with poor graft function and those with good graft function. The 3-year OS, 3-year PFS, and 1-year NRM in good graft function and poor graft function populations were 62% versus 20% (P < .0001), 53% versus 20% (P < .0001), and 12% versus 40% (P = .009), respectively. The presence of low-level DSA in the absence of desensitization did not correlate with the risk of developing graft failure and poor graft function. Patients who experienced poor graft function had worse outcomes than patients with good graft function.

P080Correlation between the reject of haploidentical transplants in patients affected by hemoglobinepathies and the presence of donor-specific anti-HLA antibodies

Aim Allogeneic haematopoietic stem cell transplantation is the treatment of choice for both pediatric and adult patients with onco-haematological diseases and non-malignant disorders. It is well known that an HLA-identical family donor is available in about 25% of cases and it is not always possible to promptly identify a voluntary donor in international registries. In the absence of a HLA-matched donor, the transplantation strategy is increasingly orienting towards the choice of allogeneic hematopoietic stem cell transplantation alternatives, such as the use of haploidentical family donors. The aim of this study was to determinate the presence in the recipients of donor specific anti-Human leukocyte antigen of class I and/or class II antibodies an correlate their potential role with the high rate of graft rejection observed. Methods The plasma or the sera of 23 patients affected by hemoglobinepathies, treated with a haploidentical transplant, were analyzed using the Mixed Antigen assay kit and subsequently, in case of positivity, with the Single Antigen beads assay kit (One Lambda, California) by Luminex technology. Results In the group of 23 transplanted patients affected by hemoglobinopathies, 9 rejected the graft. Among these, 3 (33.3%) showed the presence of DSA, while only 1 out of 14 patients with complete chimerism (7.1%) was positive for Donor-specific HLA Antibody. The presence of non-specific donor anti-Human leukocyte antigen antibodies class I and/or II was also demonstrated in 6 of the 23 patients analyzed, 3 of which were included in the group of 9 who rejected the transplantat (33.3%). Conclusions Our data showed that the presence of specific-donor anti-HLA antibodies represents a parameter associated with a higher percentage of rejection in haploidentical hematopoietic stem cell transplantation performed in patients affected by hemoglobinopathies, although a wider cohort of patients needs to be analyzed before drawing any conclusion. With the contribution of Berloni T. Galluccio: 1. Grant/Research Support; Company/Organization; IME Foundation. 2. Consultant; Company/Organization; Andreani Marco. 4. Scientific/Medical Advisor; Company/Organization; Andreani Marco. 5. Employee; Company/Organization; Galluccio Tiziana. A. Di Luzio: 1. Grant/Research Support; Company/Organization; IME Foundation. 2. Consultant; Company/Organization; Andreani Marco. 4. Scientific/Medical Advisor; Company/Organization; Andreani Marco. 5. Employee; Company/Organization; Di Luzio Andrea. M. Battarra: 1. Grant/Research Support; Company/Organization; Andreani Marco. 2. Consultant; Company/Organization; Andreani Marco. 4. Scientific/Medical Advisor; Company/Organization; Andreani Marco. 5. Employee; Company/Organization; Mariarosa Battarra.

Anti-angiotensin II type 1-receptor antibodies (AT1R-Ab) Induce a Specific Phenotype of Rejection Distinct from HLA antibody-Mediated Rejection

Anti-angiotensin II type 1-receptor antibodies (AT1R-Ab) have been associated with kidney allograft rejection; however, their ability to induce a specific rejection phenotype, independent of the presence of donor-specific anti-HLA antibodies (HLA-DSAs), has not been defined. In a prospective cohort of 881 kidney recipients transplanted between 2007 and 2010, we performed systematic screening for AT1R-Ab using quantitative ELISA and HLA-DSAs using single antigen bead assay, together with concomitant allograft biopsy, at the time of any clinical event in the first-year post-transplantation and at 1 year after transplantation. The allograft rejection phenotype was assessed by histopathology, immunochemistry for C4d complement fraction, and allograft gene expression measurement using microarray. We identified 233/881 (26%) patients with post-transplant AT1R-Ab (>10 U/mL). Compared to AT1R-Ab negative patients, AT1R-Ab positive patients showed increased levels of glomerulitis (p=0.01), peritubular capillaritis (p=0.01), endarteritis (p=0.01), similar level of interstitial inflammation (p=0.66) and tubulitis (p=0.23), and similar prevalence of C4d deposition in capillaries (p=0.24) and transplant glomerulopathy (p=0.99). After adjusting for the detection of HLA-DSAs, AT1R-Ab were independently associated with glomerulitis (aOR=1.7, p=0.006), peritubular capillaritis (aOR=1.8, p=0.002) and intimal arteritis (aOR=2.1, p=0.01). Among patients with microcirculation inflammation (g+ptc>1) (N=154), patients with AT1R-Ab and without HLA-DSA (N=23) showed increased prevalence of intimal arteritis (39%) and decreased prevalence of C4d deposition in capillaries (17%) compared to patients without AT1R-Ab and with HLA-DSA (N=80, 13% and 51%, respectively), to patients with AT1R-Ab and with HLA-DSA (N=31, 16% and 55%, respectively), and to patients without AT1R-Ab and without HLA-DSA (N=20, 5% and 10%, respectively) (p<0.001 and p=0.01, respectively). Compared to patients without AT1R-Ab and with HLA-DSA, patients with AT1R-Ab and without HLA-DSA exhibited increased expression of endothelial cell associated transcripts in allograft, including MEOX2, MEOX1 and FOSB (FC=3.9, 3.0 and 2.7, respectively, p<0.001 for all). Histomolecular rejection phenotype in patients with AT1R-Ab and without HLA-DSA was distinct from that of patients without AT1R-Ab and with HLA-DSA in unsupervised clustering. AT1R-Ab are associated with a specific histo-molecular phenotype of kidney allograft rejection, characterized by microvascular and arterial inflammation, expression of endothelial cell associated transcripts and low prevalence of complement deposition in capillaries, independent of the presence of HLA-DSAs.

Inflammation in Fibrotic Areas (i-IF/TA) Identifies a T cell-mediated Rejection Component of IF/TA with Poor Kidney Allograft Outcome

Addressing the etiological heterogeneity of interstitial fibrosis in kidney allografts represents an important challenge to improve long-term transplant outcomes. We investigated the determinants, clinical and histological phenotype, and outcome of i-IF/TA in a prospective cohort of kidney recipients. We prospectively enrolled 1539 kidney recipients transplanted between 2004 and 2010, with systematic assessment of i-IF/TA using the i-IF/TA Banff score and of tubulitis in atrophic tubules (t-IF/TA), on allograft biopsies performed at 1 year post-transplantation. We considered donor, recipient and transplant baseline characteristics, immunosuppression, infectious diseases (CMV, pyelonephritis, BK virus), presence of donor-specific anti-HLA antibodies (DSAs) and all the biopsy-proven diagnoses (T cell-mediated rejection [TCMR], antibody-mediated rejection [ABMR], recurrence, BK virus-associated nephropathy [BKVAN], calcineurin inhibithor [CNI] toxicity, acute tubular necrosis) recorded within the first year after transplantation. We identified 946 (61%) patients with IF/TA at one year post-transplant, among whom 394 (42%) patients showed i-IFTA, which was associated with t-IF/TA in 309 (78%) patients. Patients with i-IF/TA at 1 year post-transplant had significantly decreased allograft survival at 8 years compared with patients with non-inflammatory IF/TA (81% vs 87%, P=0.002). Independent risk factors for i-IF/TA included: TCMR (OR=2.7, p<0.001), BKVAN (OR=3.3, p=0.007) and HLA B (OR=1.3, p=0.012) and DR (OR=1.2, p=0.044) mismatching, while steroid therapy (OR=0.6, p=0.039), CNI therapy (OR=0.5, p=0.011) and inosine-5'-monophosphate dehydrogenase inhibitor therapy (OR=0.5, p=0.011) had protective effects on i-IF/TA occurrence. Unsupervised hierarchical clustering based on the whole spectrum of Banff elementary lesions assessed at 1 year post-transplant showed that i-IF/TA aggregated in the TCMR cluster (i, t, ti, t-IF/TA and i-IF/TA) and not in the ABMR (g, ptc, C4d, cg) and chronicity clusters (cv, ci, ct, ah). We observed a positive gradient between increasing level of i-IF/TA and t-IF/TA Banff scores and the risk of allograft loss (p<0.001). i-IFTA may reflect a TCMR subcomponent of IF/TA related to under-immunosuppression and is associated with poor kidney transplant outcome compared to non-inflammatory IF/TA.

Successful Renal Transplantation Across HLA Barrier: Report from India.

Organ donors are sometimes found “unsuitable” due to the presence of donor-specific anti-HLA antibodies in the recipient. In recent years, improved desensitization protocols have successfully helped to overcome HLA incompatibility hurdle. We present three cases where optimum desensitization was achieved in patients with the donor-specific anti-HLA antibody (DSA) leading to successful renal transplantation. All patient–donor pair underwent HLA typing, complement dependent cytotoxicity crossmatch (CDC-XM), flow cytometry XM (FC-XM), and panel reactive antibody. If any of the three tests was positive, single antigen bead assay was performed to determine the specificity of the anti-HLA antibody (s). Patients with DSA were offered organ-swap or anti-HLA antibody desensitization followed by transplantation. Desensitization protocol consisted of single dose rituximab and cascade plasmapheresis (CP) along with standard triple immunosuppression. The target DSA mean fluorescence index (MFI) was <500, along with negative CDC-XM and FC-XM for both T- and B-cells. Three patients with anti-HLA DSA, who did not find a suitable match in organ swap program, consented to anti-HLA antibody desensitization, followed by transplantation. Mean pre-desensitization antibody MFI was 1740 (1422–2280). Mean number of CP required to achieve the target MFI was 2.3 (2–3). All the three patients are on regular follow-up and have normal renal function test at a mean follow-up of 8 months. This report underlines successful application of desensitization protocol leading to successful HLA-antibody incompatible renal transplants and their continued normal renal functions.

Donor-specific anti-HLA antibodies with antibody-mediated rejection and long-term outcomes following heart transplantation

Donor-specific anti-HLA antibodies (DSA) are common after heart transplantation and are associated with rejection, cardiac allograft vasculopathy, and mortality. A noninvasive diagnostic test for pathologic antibody-mediated rejection (pAMR) does not exist. From January 1, 2010, through August 31, 2013, 221 consecutive adult patients underwent heart transplantation and were followed through October 1, 2015. The primary objective was to determine whether the presence of DSA could detect AMR at the time of pathologic diagnosis. Secondary analyses included association of DSA (stratified by major histocompatibility complex class and de novo status) during AMR with new graft dysfunction, graft loss (mortality or retransplantation), and development of cardiac allograft vasculopathy. During the study period, 69 patients (31.2%) had DSA (24% had de novo DSA), and there were 74 episodes of pAMR in 38 patients. Sensitivity of DSA at any mean fluorescence intensity to detect concurrent pAMR was only 54.3%. The presence of any DSA during pAMR increased the odds of graft dysfunction (odds ratio = 5.37; 95% confidence interval [CI], 1.34-21.47; p = 0.018), adjusting for age, sex, and timing of AMR. Circulating class II DSA after transplantation increased risk of future pAMR (hazard ratio = 2.97; 95% CI, 1.31-6.73; p = 0.009). Patients who developed de novo class II DSA had 151% increased risk of graft loss (contingent on 30-day survival) compared with patients who did not have DSA (95% CI, 1.11-5.69; p = 0.027). DSA were inadequate to diagnose pAMR. Class II DSA provided prognostic information regarding future pAMR, graft dysfunction with pAMR, and graft loss.

Cord blood transplantation in Japan.

Cord blood transplantation (CBT) has increasingly been used in Japan and the annual number of CBT now exceeds 1,200. The cumulative number of CBT reached 12,853 in 2015, accounting for almost 1/3 of total CBT performed worldwide. It is true that smaller body size and lower costs, as compared to western countries, have been advantages for Japanese people in using CB as graft alternative. In addition, several novel findings regarding serious issues following CBT have been obtained, which further enhanced the use of CB. First, several mechanisms of engraftment failure following CBT other than cell dose have been reported, such as the presence of donor-specific anti-HLA antibodies or the development of hemophagocytic syndrome. Second, unique profiles of infectious complications following CBT have been reported, such as higher incidences of early bacterial infections and HHV-6 encephalitis, as compared to those following bone marrow (BM)/peripheral blood (PB) transplants. Third, the incidence of disease relapse was comparable to those following BM/PB transplants. Novel pre-transplant conditioning regimens using intravenous busulfan have been investigated with promising results being obtained to date. A recent analysis of Japanese transplant registry data revealed similar survival following CBT to HLA-matched unrelated BM/PB transplants.

Comparative analysis of how immune sensitization is defined prior to lung transplantation

BackgroundImmune sensitization prior to lung transplantation may be associated with worse survival. Using solid phase assays to define sensitization, we assessed the relationship between PRA status, donor specific anti-HLA antibodies (DSA) pre-transplant, cytotoxic cross match results and the clinical outcomes following lung transplantation. MethodsLuminex assays determined the presence of antibodies to class I and class II MHC molecules prior to lung transplantation. At the time of transplant, the PRA status, the presence of DSA and prospective cytotoxic cross match result were analysed in 195 patients undergoing lung transplantation between June 2008 and June 2012. Clinical outcomes analysed included acute cellular and antibody-mediated rejection, chronic lung allograft dysfunction (CLAD) and mortality. ResultsAt the time of transplant, 45% of patients had a positive PRA and 29% had DSA. On univariate analysis, the presence of pre-transplant class I or II anti-HLA donor-specific antibodies was not associated with the development of chronic lung allograft dysfunction (CLAD) despite significant associations with PRA status and B-cell crossmatch. ConclusionDefining sensitization using solid phase assays provide additional details regarding donor-specific sensitization but did not provide additional prognostic information to that provided by historically available cell-based cross-match assays.

Complement activation in kidney transplantation: from risk stratification to therapeutic strategies.

One of the most important advances in transplantation medicine has been the recognition that anti-human leucocyte antigen (HLA) antibodies are destructive. Various studies over the past decade have indicated that the alloimmune response, mediated by anti-HLA antibodies, plays a key role in the failure of kidney allografts 1,2; this concept has been extended to heart, lung and composite tissue transplants 3. Although anti-HLA antibodies are considered to be harmful, there is a wide spectrum of graft injury related to these antibodies, ranging from no recognizable damage to florid rejection. The presence or absence and characteristics of donor-specific anti-HLA antibodies (DSA) are therefore crucial to determine patient outcomes following transplantation. Activation of the complement cascade is known to be a key component of antibody-mediated rejection (ABMR), and deposition of C4d is often used as a marker for complement activation 4–6. It is the ability of anti-HLA antibodies to bind complement that determines the cytotoxic potential of these antibodies 5. Therefore, we hypothesized that the presence of DSA and their ability to bind and activate complement would play a key role in solid organ transplant. A total of 1016 consecutive kidney transplant recipients were enrolled into this population-based study 7. All patients were screened for the presence of circulating DSA at the time of transplantation and at 1 year after transplantation, in patients with no immunological event or at the time of rejection using the Luminex assay. The complement-binding capacity of any detected DSA was also analysed. Of the 1016 patients, 1 year post-transplantation, 700 patients (69%) were devoid of circulating DSA and 316 patients (31%) had circulating DSA, 77 of whom (24%) were C1q-positive, i.e. had complement-binding DSA. The patients with complement-binding DSA (representing 7% of the overall population) had the poorest outcome, with a risk of graft loss 11-fold higher than patients with non-complement-binding DSA (C1q-negative) 7. Assessment of allograft biopsies (n = 1016) demonstrated that DSA, both complement (C1q-positive)- and non-complement (C1q-negative)-binding, were capable of inducing injury to the graft. Histologically, the incidence of microvascular inflammation, C4d deposition, early transplant glomerulopathy and interstitial inflammation tubulitis were significantly higher in allografts from patients with DSA (P < 0·05), particularly in those patients with C1q-positive, complement-binding DSA (P < 0·05) 7. These results were confirmed further by molecular microscopy with higher ABMR score, higher endothelial cell injury response and higher numbers of natural killer cells and interferon (IFN)-γ-inducible transcripts observed in patients with C1q-positive, complement-binding DSA. In order to translate our findings into clinical practice, we developed a risk prediction model at 1 year post-transplantation based on all histological and immunological parameters, defined by the current classical diagnosis tools. When C1q-positive, complement-binding DSA were added to the model we observed an increase in the performance and discrimination capacity, and reclassification of patients at lower or higher risk of graft loss 8. Compared with a traditional approach to predicting graft loss, we demonstrate that a new approach, which integrates the capacity of DSA to bind complement, identifies patients at high risk of graft loss and increases our risk stratification performance in kidney transplant recipients. An improved understanding of DSA mechanism of action, better patient identification and construction of risk models will pave the way to specific and personalized treatment for patients undergoing solid organ transplantation. As promising therapeutic agents targeting complement [e.g. a C5 inhibitor (eculizumab) or a C1 inhibitor] are used increasingly in patients undergoing transplantation, this study may serve as a basis for future clinical trials.