Acute Antibody-Mediated Rejection by De Novo Anti-HLA-DPβ and -DPα Antibodies After Kidney Transplantation: A Case Report

The presence of isolated de novo anti-DP antibodies is uncommon, making it difficult to determine the impact of anti-DP antibodies on graft outcome. We describe a case of acute antibody-mediated rejection mediated by de novo donor-specific anti-HLA-DP antibodies. Furthermore, the generation of non–donor-specific anti-DP antibodies (NDSAs) detected in the patient's sera was investigated. An 18-year-old woman with pretransplant 0% panel-reactive antibody received kidney transplantation from a living donor. She experienced combined acute T-cell-mediated and antibody-mediated rejection at 15 months after transplantation. High resolution HLA typing of the donor and the patient revealed that they were mismatched at both DPB1 (DPB1*31:01) and DPA1 (DPA1*02:02) loci. The single antigen bead (SAB) testing of patient's sera revealed antibodies against donor's DPB1*31:01 and DPA1*02:02 alleles. Antibodies against several non–donor-specific DP antigens were also detected. No antibodies against other HLA class I and II antigens were detected. In order to explain the reactivity pattern of NDSAs, HLAMatchmaker program was used to identify immunizing eplets shared between donor alleles and reactive beads. The analysis showed 84DEAV, a DPB1 eplet, as a shared eplet found on DPB1*31:01 (mismatched donor allele) and on DPB1-reactive alleles in SAB assay. Additionally, 50RA, a DPA1 eplet, was identified as a shared eplet found on DPA1*02:02 (mismatched donor allele) and on DPA1-reactive alleles in SAB assay. This case highlights the clinical significance of HLA-DP antibodies. Furthermore, the generation of NDSA anti-DP antibodies by epitope sharing underscores the importance of HLA-DP epitope matching in kidney transplantation.     

Epitope analysis of DQ6-reactive antibodies in sera from a DQ6-positive transplant candidate sensitized during pregnancy

This case report describes DQ6-reactive serum antibody reactivity in a patient who types as DQ6. DNA typing showed DQB1*06:09 on the antibody producer and serum reactivity with DQB1*06:01, *06:02 and *06:03 but not with *06:04 and *06:09. HLAMatchmaker serum analysis showed antibody reactivity with a new antibody-verified 85VA eplet on DQB but additional reactivity with DQB1*02:01 could not be readily interpreted. After applying the nonself-self algorithm of HLA immunogenicity we have identified a new DQB epitope structurally described as 140A₂ + 130R + 135D and shared by DQB1*02:01 and DQB1*05:01 and DQB1*06:02 of the immunizer.     

Racial differences in incident de novo donor‐specific anti‐HLA antibody among primary renal allograft recipients: results from a single center cohort study

Controversy exists as to whether African American (AA) transplant recipients are at risk for developing de novo donor‐specific anti‐human leucocyte antigen (HLA) antibody (dnDSA). We studied 341 HLA‐mismatched, primary renal allograft recipients who were consecutively transplanted between 3/1999 and 12/2010. Sera were collected sequentially pre‐ and post‐transplant and tested for anti‐HLA immunoglobulin G (IgG) via single antigen bead assay. Of the 341 transplant patients (225 AA and 116 non‐AA), 107 developed dnDSA at a median of 9.2 months post‐transplant. AA patients had a 5‐year dnDSA incidence of 35%. This was significantly higher than the 5‐year dnDSA incidence for non‐AA patients (21%). DQ mismatch (risk) and receiving a living‐related donor (LRD) transplant (protective) were transplant factors associated with dnDSA. Within the AA patient cohort, HLA‐DQ mismatch, not‐receiving a LRD transplant, nonadherence and BK viraemia were the most common factors associated with early dnDSA (occurring <24 months post‐transplant). Nonadherence and pretransplant diabetes history were the strong precursors to late dnDSA. Despite the higher rates of dnDSA in the AA cohort, post‐dnDSA survival was the same in AA and non‐AA patients. This study suggests that DQ matching, increasing LRD transplantation in AA patients and minimizing under‐immunosuppression will be key to preventing dnDSA.     

A method for HLA-DQA typing by the PCR-SP technique

Abstract There is preliminary evidence that matching for HLA-DQ is important for kidney graft survival. We developed a method for HLA-DQA typing based on the PCR-SP principle. The procedure consisted of three steps: DNA isolation, PCR amplification and visualization of the PCR product under UV light. For the identification of all currently known DQA1 alleles, we designed 18 different primers that allowed typing for the specificities DQA1*0101, *1012, *0103, *0104, *0201, *03, *0401, *0501 and DQA1*0601. For the typing of a single individual, 12 PCR mixes were needed, each containing a primer pair specific for a certain allele group, and a pair of control primers that amplified a non-polymorphic region. The time required for this procedure was approximately 3 h from the time of blood collection. Comparison of this method with DQA typing by the RFLP method in 151 individuals revealed only a single discrepancy. The method can be easily applied for prospective cadaver donor typing.     

Shared Molecular Eplet Stimulates Acute Antibody-Mediated Rejection in a Kidney Transplant Recipient With Low-Level Donor-Specific Antibodies: A Case Report

HLA antibodies usually recognize epitopes rather than antigens. This case report reveals that acute antibody-mediated rejection (AMR) that occurred in a kidney transplant recipient with low-level donor-specific antibodies (DSAs) could be explained by shared epitope. A 39-year-old woman received a first kidney transplant from a deceased donor (HLA-DRB1*11:06, *12:02, DRB3*02:02, *03:01). She developed acute AMR confirmed by kidney biopsy on day 4 after transplantation. Antibody testing with pretransplant serum showed anti-DR11 DSA below cutoff level (mean fluorescence intensity [MFI], 702; cutoff >1,000). However, high-level DSAs were detected on day 5 after transplantation (anti-DR11 MFI, 8,531; anti-DR12 MFI, 3,146). We hypothesized that the sharp rise in DSA levels was a result of anamnestic response with donor-antigen sensitization that occurred during pregnancy. High-resolution HLA-DR typing of her husband showed HLA-DRB1*03:01, *15:02:01, DRB3*02:02, DRB5*01:02. No sharing between donor HLAs eliciting reactive antibodies and her husband's HLAs was detected. Nevertheless, we speculated that shared epitope, not antigen, was the cause of allosensitization. To identify the shared epitope recognized by patient's antibodies, we used HLAmatchmaker, a computer algorithm that considers small configurations of polymorphic residues referred to as eplets as essential components of HLA epitopes for analysis. The results showed that 149H, which was the eplet shared by HLA-DRB1*03:01 (from her husband) and DRB1*11:06, DRB1*12:02, DRB3*03:01 (from donor), was the most prevalent eplet on DRB1 reactive alleles in Luminex assay. In conclusion, pretransplant low-level DSAs can induce AMR early after transplantation as a result of shared epitopes with a previous immunizer.     

Association between HLA class II locus and the susceptibility to Artemisia pollen-induced allergic rhinitis in Chinese population.

OBJECTIVE: The aim of the study was to determine whether susceptibility or resistance to Artemisia pollen-induced allergic rhinitis was associated with HLA class II DQA1, DQB1 loci.Study design and setting Forty-one subjects with allergic rhinitis and 41 healthy controls from Beijing were genotyped at HLA class II DQA1, DQB1 alleles by polymerase chain reaction amplification with sequence-specific primers-based technique. RESULTS: The allele frequencies of HLA-DQA1*0201, DQB1*0602 were lower in patients with allergic rhinitis compared with the controls (24.39% versus 46.34%, P = 0.038; 4.88% versus 26.83%, P = 0.007), and the frequency of DQA1*0302 was higher among patients than the controls (58.54% versus 14.63%, P = 0.00004, Pc = 0.0004). CONCLUSION AND SIGNIFICANCE: HLA-DQA1 and -DQB1 genes may be involved in the development of Artemisia pollen-induced allergic rhinitis. HLA-DQA1*0201, DQB1*0602 alleles may be a protective factor and DQA1*0302 may be a susceptible factor for Artemisia pollen-induced allergic rhinitis.     

Acute Antibody-mediated Rejection Possibly Due to Anti–human Leukocyte Antigen DQB1 Antibodies after Renal Transplantation – Case Report

A 61-year-old Japanese woman, who had undergone hemodialysis because of chronic glomerulonephritis, received a living renal transplant from her ABO blood type–compatible spouse. HLA typing of A, B and DRB showed 3/6 mismatches. Complement-dependent cytotoxicity crossmatches, HLA antibody screening with the use of flow panel reactive antibody (PRA), and flow cytometry crossmatches (FCXM) were all negative. Tacrolimus, mycophenolate mofetil, methylprednisolone (MP), and basiliximab induction were used as the standard immunosuppressive therapy. After renal transplantation, her serum creatinine level favorably decreased, but urine output was not sufficiently obtained, contrary to our expectations. Doppler sonography revealed disappearance of diastolic arterial flow on postoperative day 2. The episode biopsy showed acute antibody-mediated rejection (AMR) based on the current Banff classification, although FCXM and flow PRA were still negative. To determine the cause of acute AMR, we expanded the HLA typing at high resolution levels to Cw, DQB1, and DPB1. Retrospective analysis of perioperative sera demonstrated the presence of low levels of donor-specific HLA IgG and moderate levels of IgM antibody against DQB1 before transplantation. There was an elevation of IgM antibody at the time of rejection, whereas IgG antibody showed no remarkable change. AMR was successfully treated with plasma exchange, low-dose intravenous immunoglobulin, high-dose intravenous MP pulse, and rituximab.     

Human leukocyte antigen class II DQ alpha and beta epitopes identified from sera of kidney allograft recipients

BACKGROUND: Epitopes are the sites to which antibodies bind. Both alpha and beta peptide chains of the human leukocyte antigen-DQ heterodimers (DQA1 and DQB1, respectively) contain polymorphic regions. We can identify DQA1 and DQB1 epitopes by DQ single antigen beads assay of the antibodies, correlating the beads' reaction patterns with either DQA1 or DQB1 alleles. METHODS: Sera from 74 transplant patients and 35 mouse DQB1 monoclonal antibodies were tested with DQ single antigen beads for their DQ allelic and serological specificities. Epitopes were defined by amino acids shared by the positive antigens of the antibodies. Unique amino acids were identified as potential epitope sites by comparing the peptide sequences of all human leukocyte antigen class II alleles. For the absorption or elution, patient's serum sample was absorbed by a homozygous B-lymphoblast cell line of specific DQ typing, the eluted antibody then tested with single antigen beads to demonstrate that the antibody reacted to a single epitope shared by multiple DQ antigens. RESULTS: Three DQA1 and 15 DQB1 epitopes were identified. We found that 21 patients produced antibodies against one of the DQA1 epitopes; 27 patients produced antibodies against one of the DQB1 epitopes. CONCLUSION: The DQA1 and DQB1 epitopes identified here seem to be immunogenic and to elicit DQ antibodies. For the DQB1 epitopes, multiple DQ serological specificities that were detected in the serum of a transplant patient could be explained as a single donor-specific DQ antibody reacting to a mismatched DQ epitope of the donor. Ten examples are shown here.     

Heterozygosity or homozygosity for 2 HLA class II haplotypes predict favorable outcomes for renal cell carcinoma treated with cytokine therapy

PURPOSE: Durable responses to cytokine therapy occur in a small subset of patients with renal cell carcinoma. We determined if a common HLA genotype existed among these patients which might be associated with response and survival. MATERIALS AND METHODS: The study population consisted of 80 patients with metastatic renal cell carcinoma who had received cytokine therapy. DNA obtained from these patients was used for high resolution typing of HLA A, B, C, DRB1, DQA1 and DQB1 alleles. RESULTS: The class II alleles from patients with prolonged disease-free survival were predominantly composed of haplotype DRB1*0301/DQA1*0501/DQB1*0201 and DRB1*1501/DQA1*0102/DQB1*0602. The frequency of heterozygosity or homozygosity for these alleles was significantly greater in the good outcome group of patients than in those whose disease progressed during therapy. Heterozygosity or homozygosity at these loci was also associated with significant prolongation of survival. CONCLUSIONS: We conclude that heterozygosity or homozygosity for the class II haplotypes DRB1*0301/DQA1*0501/DQB1*0201 and DRB1*1501/DQA1*0102/DQB1*0602 is associated with durable response and survival in patients with metastatic renal cell carcinoma treated with cytokine therapy.     

Definition of High-Risk Type 1 Diabetes HLA-DR and HLA-DQ Types Using Only Three Single Nucleotide Polymorphisms

Evaluating risk of developing type 1 diabetes (T1D) depends on determining an individual’s HLA type, especially of the HLA DRB1 and DQB1 alleles. Individuals positive for HLA-DRB1*03 (DR3) or HLA-DRB1*04 (DR4) with DQB1*03:02 (DQ8) have the highest risk of developing T1D. Currently, HLA typing methods are relatively expensive and time consuming. We sought to determine the minimum number of single nucleotide polymorphisms (SNPs) that could rapidly define the HLA-DR types relevant to T1D, namely, DR3/4, DR3/3, DR4/4, DR3/X, DR4/X, and DRX/X (where X is neither DR3 nor DR4), and could distinguish the highest-risk DR4 type (DR4-DQ8) as well as the non-T1D–associated DR4-DQB1*03:01 type. We analyzed 19,035 SNPs of 10,579 subjects (7,405 from a discovery set and 3,174 from a validation set) from the Type 1 Diabetes Genetics Consortium and developed a novel machine learning method to select as few as three SNPs that could define the HLA-DR and HLA-DQ types accurately. The overall accuracy was 99.3%, area under curve was 0.997, true-positive rates were >0.99, and false-positive rates were <0.001. We confirmed the reliability of these SNPs by 10-fold cross-validation. Our approach predicts HLA-DR/DQ types relevant to T1D more accurately than existing methods and is rapid and cost-effective.Type 1 diabetes (T1D) is an autoimmune disease with both genetic and environmental components. More than 60 genes have been identified to affect the risk of T1D, with the HLA loci having the greatest impact on susceptibility (1,2). The association of T1D with alleles at HLA loci, especially the HLA class II genes DR and DQ, is well-validated (3). The DR-DQ types contributing the most risk are HLA-DRB1*03 (DR3), typically observed in haplotypic association with DQA1*05:01-DQB1*02:01 (DQ2), and HLA-DRB1*04 (DR4) in haplotypic association with DQA1*03-DQB1*03:02 (DQ8). The highest risk is seen in individuals who are heterozygous for these types. In contrast, HLA-DRB1*04 (DR4) in haplotypic association with DQA1*03-DQB1*03:01 (DQ7) is not associated with a high risk for T1D.HLA allele typing assists in determining risk for T1D and in studies to understand the pathogenesis of T1D. It is particularly useful in prevention and intervention trials that test potential preventative treatments in high-risk subjects (4). HLA typing also is required in genetic studies aimed at determining the molecular basis of T1D susceptibility, such as those performed by the Type 1 Diabetes Genetics Consortium (T1DGC) (5). However, the high cost of HLA genotyping not only is a major imposition on such large-scale programs but also is beyond the reach of small research groups. Several studies have recently undertaken prediction of HLA alleles using single nucleotide polymorphism (SNP) variation within the region (6–9). However, these methods did not focus on DR-DQ types, so the accuracy of prediction was not high even though a relatively large set of typed SNPs within the major histocompatibility complex (MHC) was used (e.g., 49 selected SNPs were used to impute HLA-B, HLA-DRB1, and HLA-DQB1 types in 9). Barker et al. (10) set the scene for rapid identification of HLA haplotypes relevant to T1D by finding two SNPs that could identify the HLA type with the highest risk for T1D, namely DR3/DR4 and DQ8. However, they only reported the predictive results for DR3/4 heterozygotes. Individuals homozygous for DR3 or DR4 also have an increased risk for developing T1D, but these and other DR types relevant to T1D were not distinguished by these SNPs (10).We therefore sought to find a minimal set of SNPs that could accurately annotate the six major DR type categories relevant for T1D risk: heterozygosity for DR3 and DR4 (denoted here as DR3/4); homozygosity for DR3 or DR4 (DR3/3 or DR4/4, respectively); carriage of a single DR3 type and a non-DR3, non-DR4 type (DR3/X); carriage of a single DR4 type and a non-DR3, non-DR4 type (DR4/X); and absence of both DR3 and DR4 (DRX/X). In addition, we reviewed the previously described SNPs for the DR3/DR4 and DQ8 types and sought to annotate the risk associated with different DR4 types: DR4-DQ8 (DQB1*03:02) and DR4-DQ7 (DQB1*03:01).     

Hyperacute rejection in ABO-incompatible kidney transplantation: Significance of isoagglutinin subclass

IntroductionABO-incompatible transplantation has expanded the limited donor pool for kidney transplantation. Despite the successful desensitization protocols and immunosuppression, undesirable cases of hyperacute rejection occurs.ObjectiveFlow cytometry was used to measure isoagglutinin titer and its IgG subclasses in assessment of the cause of hyperacute rejection in ABO-incompatible kidney transplantation.Materials and methodsThe recipient was admitted for kidney transplantation due to end-stage renal disease. Pre-transplantation work-up for ABO-incompatible kidney transplantation included blood group typing, HLA DNA typing and HLA antibody analyses. HLA crossmatch analysis was conducted using donor lymphocytes and anti-HLA antibody assay using Luminex panel reactive antibody test (One Lambda, Inc., Canoga Park, CA). Desensitization protocol was composed of therapeutic plasma exchange sessions and rituximab.ResultsDespite negative HLA crossmatch results, a case of hyperacute rejection occurred after living donor kidney transplantation. Rejection resulted in immediate removal of graft, and the patient later received a second kidney transplantation. Retrospective evaluation of isoagglutinin titer and its subclasses using flow cytometry identified the cause of rejection to increased IgG1 subclass. Desensitization protocol for ABO-incompatible kidney transplantation now implements further caution for blood group O recipients.DiscussionHyperacute rejection resulting from increased IgG1 isoagglutinin subclass has not been previously confirmed using flow cytometry. Unfortunate outcome of this rejection case provides insight to how we should approach and ensure successful ABO-incompatible kidney transplantation.     

Predictive value of HLAMatchmaker and PIRCHE-II scores for de novo donor-specific antibody formation after adult and pediatric liver transplantation

Production of de novo DSA (dnDSA) is associated with an increased risk of antibody mediated rejection after liver transplantation. Antibodies not only recognize the entire antigen but are able to bind specific functional epitopes present on the HLA molecule surface. The HLAMatchmaker and the PIRCHE-II (predicted indirectly recognizable HLA epitopes) algorithms are able to determine predictive epitope mismatches scores and de novo DSA (dnDSA) synthesis based on alloreactive eplets' identification. The aim of the present study was to assess, for the first time in liver transplantation, the complementarity between these two algorithms. We retrospectively analyzed a cohort of 407 adult and 133 pediatric liver transplant patients without preformed DSA, transplanted between 1991 and 2019 in Lyon and Montpellier. HLA antibodies were detected by single antigen bead assay. HLA typing of the donor-recipient pair was achieved by serological and/or DNA-based techniques. PIRCHE-II and HLAMatchmaker algorithms were then applied on both groups. During follow-up, 27.3% of adults and 38.3% of children developed dnDSA. HLA-DRB1 and DQB1-PIRCHE-II and HLAMatchmaker scores were significantly higher in dnDSA group compared to no DSA group for both pediatric and adult patients (except for PIRCHE-II HLA-DRB1 locus score in pediatrics). ROC curves allowed determining score thresholds classifying patients in low- and high-risk of dnDSA synthesis. The two algorithms' Kaplan-Meier curves showed a predicted incidence of dnDSA 20 years after transplantation significantly lower in the low-risk group compare with the high-risk group (log rank <0.05), in both cohorts, with a good negative predictive value. In conclusion, HLAMatchmaker and PIRCHE-II algorithms both are effective tools to identify anti-HLA immunization risk and to predict dnDSA formation after liver transplantation.     

New DQA1 allele specific antibody against epitope 2D (an exon 1 encoded amino acid). Considerations for alleles under the same P-group designation

The majority of polymorphisms of the Human Leukocyte Antigen (HLA) proteins are clustered at the peptide binding domain (PBD), defined as the area coded by exon 2 and 3 for class I and exon 2 for class II. HLA alleles with the same amino acid (AA) sequence at the PBD are considered functionally equivalent and can be grouped under the same P-group designation. Here we present a case of a kidney recipient, typed as DQA1*01:04, 01:05 and DQB1*05:01P, 05:03, who developed antibodies against all DQ antigens on our Luminex Single Antigen (LSA) panel. Our LSA panel does not include DQA1*01:05 or 01:04, but both alleles belong to the DQA1*01:01P group and beads carrying DQA1*01:01 tested positive. Mature protein sequence alignment demonstrated a single AA mismatch between DQA1*01:04/01:05 and DQA1*01:01 located at position 2 (G vs D), which is encoded by exon 1. Luminex assay by another manufacturer which include a bead carrying patient's own DQA1* type and crossmatch studies with surrogate donors confirmed the presence of an antibody against mismatched epitope 2D. This case illustrates that alleles included in the same P-group may have polymorphisms able to trigger immunological responses and brings attention to the fact that some mature HLA proteins express AA encoded by exon 1, which is structurally part of the PBD.     

The Importance of New Generation Sequencing (NGS) HLA Typing in Renal Transplantation—Preliminary Report

Introduction

Thanks to new generation sequencing (NGS) and expansion of HLA typing with additional loci, it will be possible to increase the effectiveness of graft survival and to avoid complications related to the immune system. New pharmacogenetic factors are still being researched to develop better immunosuppressive treatment.

Evolution and Clinical Pathologic Correlations of De Novo Donor‐Specific HLA Antibody Post Kidney Transplant

The natural history for patients with de novo donor‐specific antibodies (dnDSA) and the risk factors for its development have not been well defined. Furthermore, clinical and histologic correlation with serologic data is limited. We studied 315 consecutive renal transplants without pretransplant DSA, with a mean follow‐up of 6.2 ± 2.9 years. Protocol (n = 215) and for cause (n = 163) biopsies were analyzed. Solid phase assays were used to screen for dnDSA posttransplant. A total of 47 out of 315 (15%) patients developed dnDSA at a mean of 4.6 ± 3.0 years posttransplant. Independent predictors of dnDSA were HLA‐DRβ1 MM > 0 (OR 5.66, p < 0.006); and nonadherence (OR 8.75, p < 0.001); with a strong trend toward clinical rejection episodes preceding dnDSA (OR 1.57 per rejection episode, p = 0.061). The median 10‐year graft survival for those with dnDSA was lower than the No dnDSA group (57% vs. 96%, p < 0.0001). Pathology consistent with antibody‐mediated injury can occur and progress in patients with dnDSA in the absence of graft dysfunction and furthermore, nonadherence and cellular rejection contribute to dnDSA development and progression to graft loss.     

Proteasome inhibition by bortezomib: effect on HLA-antibody levels and specificity in sensitized patients awaiting renal allograft transplantation

BackgroundSensitization to human leukocyte antigen (HLA) prolongs waiting list time and reduces allograft survival in solid organ transplantation. Current strategies for pretransplant desensitization are based on B-cell depletion and extracorporeal treatment. The proteasome inhibitor bortezomib allows direct targeting of the antibody-producing plasma cell and has been used in antibody-mediated rejection (AMR) and recipient desensitization with varying results. Here, we report the effect of bortezomib preconditioning on HLA antibody titers and specificity in highly sensitized patients awaiting renal allograft transplantation.Patients and methodsTwo highly sensitized patients awaiting third kidney transplantation were given one cycle of bortezomib (1.3 mg/m², days 1, 4, 8, 11), as part of recipient desensitization. Time-course and levels of anti-HLA antibodies, as well as specificity to previous transplant antigens were monitored by luminex technology. In addition, measles and tetanus toxoid immunoglobulin G (IgG) was measured.ResultsFollowing bortezomib, overall changes in IgG levels were small and no sustained reduction in anti-HLA class I or II antibody levels was observed over more than 100 days of follow-up to both, donor specific and non-donor specific antigens. Moreover, anti-measles and -tetanus toxoid IgG levels remained unchanged.ConclusionsBortezomib preconditioning alone does not result in sustained reduction of HLA antibody levels or alter protective immunity in sensitized patients. This supports the notion, that bortezomib requires activation of plasma cells, as in AMR, to effectively reduce HLA antibody production. Hence, in a pretransplant setting, combination strategies may be required to derive benefit from proteasome inhibition.     

多聚酶链反应－序列特异性寡核苷酸探针杂交－HLADQA分型在肾移植中的应用

我院于１９９２年开始应用多聚酶链反应（ＰＣＲ）技术，对同种异体肾脏移植的供受者ＨＬＡ－Ⅱ类抗原进行基因分型。通过４０例患者基因分型结果表明：肾移植患者供受者有１～２个ＨＬＡＤＱＡ等位基因相符者，移植肾１年存活率１００％；完全不相符者，１年存活率３３％，两者有非常显著性差异（Ｐ＜０．００５）。采用此方法对器官移植供受者进行基因分型，可大大提高供受者间组织相容性相符程度，减少或减轻排斥反应的发生，以期提高移植物的存活质量，获得更好的临床效果。     

Clinical significance of low pre-transplant donor specific antibodies (DSA) in living donor kidney recipients with negative complement-dependent cytotoxicity crossmatches (CDCXM), and negative flow cytometry crossmatches (FLXM) – A single-center experience

BackgroundIt is controversial whether all donor-specific antibodies (DSA) detected by the solid-phase single antigen bead (SAB) assay negatively affect kidney transplantation outcomes. The study aimed to evaluate the possible clinical significance of low pre-transplant DSA in living donor kidney recipients. We analyzed a group of patients with HLA-A, B, and -DR DSA reactivities below a virtual crossmatch (VXM) value of 5000 MFI but with all VXM DSA reactivities at HLA-DQ, -DP, and -Cw, which were not typed routinely for donors prior to transplantation. We also investigated the incidence of persistent and de novo DSAs in available posttransplant SAB assays.MethodsFrom the historical cohort of living donor recipients transplanted between 2014 and 2018 at our center (n = 82), 55 patients met the inclusion criteria, namely: these patients were > 18 years old with non-HLA identical sibling donors, who were not desensitized, who had available pre-transplant SAB results, and who had negative both complement-dependent cytotoxicity crossmatch (CDCXM) and flow cytometry crossmatch (FLXM) results. An additional donor HLA typing, performed for all 55 recipients, identified donor additional HLA-DQ, -DP, and -Cw DSA reactivities. These patients were then divided by SAB reactivity into three groups: 1) those with DSA-positive reactivities; 2) those with non-donor-specific anti-HLA reactivities (NDSA); and, 3) those who were anti-HLA-negative. All these recipients were followed for three years and checked for their de novo or persistent DSA.ResultsIn the studied cohort, DSA-positive, NDSA reactive, and anti-HLA negative recipients constituted 33%, 36%, and 31% of 55 patients, respectively. Non-routinely considered pre-transplant HLA-DQ, -DP, and -Cw DSA-positive reactivities were shown in as many as 78% of DSA-positive cases (group 1) with the lowest MFI value of 319 to DP4 and the highest MFI of 5767 to DQ2. Of the pre-transplant HLA-A, B, and -DR DSA reactivities, only -DR52 DSA reactivity reached the highest MFI value of 2191. These detected DSAs did not reduce the mean estimated glomerular filtration rate (eGFR) values and did not increase the incidence of proteinuria in recipients. While the 3-year graft survival was lower in the DSA-positive group (94.4%) with one recipient who lost kidney transplant, the difference was not significantly different (p = 0.7) from the NDSA (100%) and negative (100%) groups. In terms of the incidence of de novo acute antibody-mediated rejection (AMR) at three years after transplantation, no case has been reported in the cohort. This may suggest that low DSA-positive recipients do not experience higher rejection rate. However, DSA-positive recipients had a tendency for a higher frequency of C4d deposits in peritubular capillaries (PTC) and de novo DSA.ConclusionOur 3-year follow-up of patients with low pre-transplant DSA found no association with a deterioration in graft function and worse graft survival. Furthermore, we did not observe an increase in AMR in our patients with low DSA. A larger cohort and a longer follow-up period may be needed to evaluate the tendency of low DSA-positive recipients towards the higher incidence of C4d deposits in PTC and/or de novo DSA.     

Anti–Angiotensin Type 1 Receptor Antibodies Associated With Antibody-Mediated Rejection in Patients Without Preformed HLA-Donor–Specific Antibody

IntroductionAngiotensin II is a peptide hormone involved in the renin-angiotensin system (RAS). Anti–angiotensin receptor 1 (AT1R) antibodies are implicated in stimulating RAS and are suspected to have some adverse impacts on renal transplantation outcome.MethodsFrom November 2009 to February 2012, 37 remaining sera from renal transplantation recipients with biopsy-proven antibody-mediated rejection (AMR) (n = 6), acute cellular rejection (ACR) (n = 23), and AMR + ACR (n = 8) without preformed human leukocyte antigeon (HLA) antibodies were tested with anti-AT1R antibody assay. Forty-two control patients without rejection also were analyzed.ResultsThe frequency of elevated anti-AT1R antibodies was higher in patients with AMR (n = 14) compared to controls (28.6% vs 4.9%, P = .03, OR = 8.0). It was also higher in patients with AMR + ACR (n=8) (37.5% vs 4.9%, P = .03, OR = 12.0). There was no difference in frequencies of elevated anti-AT1R antibody in patients with ACR.ConclusionAnti-AT1R antibodies were suspected to be associated with occurrence of AMR without preformed HLA antibodies in renal transplantation. Further studies in a larger number of patients are needed.     

Particular HLA-DQ alpha beta heterodimer associated with IDDM susceptibility in both DR4-DQw4 Japanese and DR4-DQw8/DRw8-DQw4 whites

Insulin-dependent diabetes mellitus (IDDM) susceptibility is associated with the DR4-DQw4 haplotype in Japanese and the DR4-DQw8/-Drw8-DQw4 genotype (among others) in whites. We investigated whether these Japanese and white individuals encode the same or a similar DQ alpha beta heterodimer, which may be an IDDM-susceptibility molecule in both populations. First, we carried out genomic DQA1 and DQB1 typing with sequence-specific oligonucleotide probes. The results revealed that Japanese DR4-DQw4 and white DR4-DQw8/DRw8-DQw4 IDDM patients carried the DQA1*0301 allele and the DQB1*0401 or DQB1*0402 allele, either in the cis (Japanese DR4-DQw4 individuals) or trans (white DR4-DQw8/DRw8-DQw4 individuals) position. Because the DQB1*0401 and DQB1*0402 alleles differ only at residue 23, these DQB1 genes are very similar. We next tested cells from these individuals with a particular DQ-specific T-lymphocyte clone, HH58. The clone was only restimulated with cells from Japanese individuals who carried the DQA1*0301 and DQB1*0401 alleles in the cis position or white individuals who carried the DQA1*0301 and DQB1*0402 alleles in the trans position. Thus, particular cis- or trans-encoded DQ alpha beta heterodimers, which in both cases are recognized by T lymphocytes, may confer susceptibility to IDDM in both ethnic groups.