Improved Graft Function following Desensitization of Anti-AT1R and Autoantibodies in a Heart Transplant Recipient Negative for Donor-Specific Antibodies with Antibody-Mediated Rejection: A Case Report.

HLA donor-specific antibodies (DSAs) pre and post transplant increase the risk of antibody-mediated rejection (AMR) and lead to poor graft survival. Increasing data exist to support the involvement of non-HLA antibodies in triggering an immunological response. The development of non-HLA antibodies specific for AT1R is associated with poor clinical outcomes in orthotopic heart transplant recipients. This case presents an investigation of non-HLA antibodies in a 56-year-old female heart transplant recipient diagnosed with AMR in the absence of DSAs.

Specificity of HLA monoclonal antibodies and their use to determine HLA expression on lymphocytes and peripheral blood stem cells.

HLA Class I and II expression are known to differ locus-to-locus, however, HLA expression on the cell-surface is frequently reported as the total amount of HLA Class I or II antigens. This is despite evidence that indicates the differential expression of HLA can influence patient outcomes post-transplantation. Although numerous commercially available HLA monoclonal antibodies (mAbs) exist to characterize HLA expression, there is currently a lack of detailed information regarding their reactivities to HLA specificities. The specificities of locus-specific HLA mAbs (nine Class I and four Class II mAbs) were evaluated by two solid-phase Luminex single antigen bead assays. The reactivity patterns of these mAbs were then confirmed by flow cytometry using lymphocytes and PBSCs (peripheral blood stem cells). Out of the 13 HLA mAbs tested, only four (one Class I and three Class II mAbs) displayed intra-locus reactivity without also reacting to inter-locus specificities. Epitope analysis revealed the presence of shared epitopes across numerous HLA loci, explaining much of the observed inter-locus reactivity. The specificity of the HLA mAbs seen in solid-phase assays was confirmed against PBSCs and lymphocytes by flow cytometry. Using this method, we observed differences in the cell surface expression of HLA-C, HLA-DR, HLA-DQ, and HLA-DP between PBSCs and lymphocytes. Our results emphasize the need to characterize the reactivity patterns of HLA mAbs using solid-phase assays before their use on cells. Through understanding the reactivity of these HLA mAbs, the cellular expression of HLA can be more accurately assessed in downstream assays.

Treatment of allosensitized patients receiving allogeneic transplantation.

Donor-specific anti-HLA antibodies (DSAs) are a major cause of engraftment failure in patients receiving haploidentical stem cell transplantation (HaploSCT). Effective treatments are needed for these patients, who often have no other donor options and/or are in need to proceed urgently to transplantation. We studied a multimodality treatment with alternate-day plasma exchange (PE), rituximab, intravenous γ globulin (IVIg) and an irradiated donor buffy coat for patients with DSAs at 2 institutions. Thirty-seven patients with a median age of 51 years were treated with this desensitization protocol. Treatment outcomes were compared with a control group of HaploSCT patients without DSAs (n = 345). The majority of patients in the DSA group were female (83.8% vs 37.1% in controls, P < .001) and received stem cells from a child as the donor (67.6% vs 44.1%, P = .002). Mean DSA level before and after desensitization was 10 198 and 5937 mean fluorescence intensity (MFI), respectively, with mean differences of 4030 MFI. Fourteen of 30 tested patients (46.7%) had C1q positivity, while 8 of 29 tested patients (27.6%) remained positive after desensitization. In multivariable analysis, patients with initial DSA > 20 000 MFI and persistent positive C1q after desensitization had a significantly lower engraftment rate, which resulted in significantly higher non-relapse mortality and worse overall survival (OS) than controls, whereas graft outcome and survival of patients with initial DSA < 20 000 MFI and those with negative C1q after treatment were comparable with controls. In conclusion, treatment with PE, rituximab, IVIg, and donor buffy coat is effective in promoting engraftment in patients with DSAs ≤20 000 MFI.

Role of renin-angiotensin system inhibitors in retardation of progression of end-stage renal failure: a retrospective study.

BACKGROUND: Few studies have examined how renin-angiotensin system inhibitors (RASI) delay dialysis initiation in patients with advanced chronic kidney disease (CKD). We conducted a retrospective survey to examine this subject. METHODS: We reviewed the records of patients with advanced CKD for the 60-month period before dialysis initiation between 1990 and 2015. Patients were classified based on the decade of dialysis initiation into the 1990s, 2000s, and 2010s groups. The rates of antihypertensive medications administered were assessed. The rate of decline of renal function was evaluated by the slope of reciprocal serum creatinine (SRSC). Multiple regression analyses were conducted to evaluate factors contributing to renoprotection. RESULTS: The duration of RASI administration was longer in the 2010s than in 2000s and 1990s. Both diabetic and non-diabetic patients had lower SRSC in the 2010s compared to the 2000s. In the 2010s, the rate of RASI administration during the 60-month pre-dialysis period showed an initial rise followed by a downward trend, although the rates of administration of the other classes of antihypertensives increased continuously. Multivariate regression analyses identified age, blood pressure, diuretics, α-blockers, α-methyldopa and RASI as independent predictors of SRSC in the 2010s. The rate of RASI administration correlated with serum potassium concentration. CONCLUSION: Our findings suggest that in the 2010s, RASI with other antihypertensive agents contributed to renoprotection in advanced CKD patients, but they were underused because of the concern over hyperkalemia. In real-world clinical practice, physicians may feel great hesitation in using RASI in patients with advanced CKD.

Risk Stratification of Human Leukocyte Antigen Class II Donor Specific Antibody Positive Patients by Immunoglobulin G Subclasses.

BACKGROUND: Human leukocyte antigen (HLA) antibodies are a major cause of graft loss in mismatched transplant recipients. However, the time to graft loss resulting from antibody induced injury is unpredictable. The unpredictable nature of antibodies may be related to the subclass of antibodies. In this study, HLA immunoglobulin G (IgG) subclasses were investigated to determine whether a unique IgG subclass composition could better identify those patients at eminent risk for graft loss. METHODS: The serial serum samples from the 57 patients with post-transplant HLA class II donor specific antibodies (DSA) were tested for the three IgG subclasses (IgG1, IgG3, and IgG4). RESULTS: IgG3 and IgG4 were highly prevalent in failed patients compared to functioning patients (82 % vs. 34%, 45% vs. 20%, respectively). IgG3 development showed a distinct subclass trend between failed and functioning patients with poor graft survival (log rank p=0.0006). IgG1 was almost equally abundant in both groups (100% and 97%, respectively). Of the 5 patterns of IgG subclass combinations observed, IgG1+3+ showed the strongest association with graft failure (hazard ratio 3.14, p=0.007). CONCLUSION: Patients with IgG3 subclass HLA DSA showed lower graft survival. Post-transplant monitoring for IgG subclasses rather than total IgG monitoring may identify patients at risk for graft failure.

Association of anti-human leukocyte antigen and anti-angiotensin II type 1 receptor antibodies with liver allograft fibrosis after immunosuppression withdrawal.

BACKGROUND: Many pediatric patients who receive a living-donor liver transplant undergo withdrawal of immunosuppression (IS). For them, the high incidence of long-term progressive graft fibrosis is of particular concern. METHODS: We conducted a cross-sectional study including 81 pediatric patients who underwent IS withdrawal after living-donor liver transplant at Kyoto University Hospital and whose serum samples and pathological data could be obtained during the analysis period. We examined the association of donor-specific anti-human leukocyte antigen (HLA) antibody (DSA) and angiotensin II type 1 receptor antibody (anti-AT1R Ab) with posttransplant graft fibrosis. Normalized mean fluorescence intensity (MFI) 5,000 or higher and anti-AT1R Ab concentrations 17 U/mL or higher were both considered high level. The patients were classified into an advanced fibrosis group (AFG) (Ishak score ≥ 3) and a control group (CG) (Ishak score ≤ 2). RESULTS: Only one patient demonstrated DSA class I. Among those who demonstrated DSA class II, more AFG patients than CG patients demonstrated high-level mean fluorescence intensity, although the difference was not significant (64% vs. 39%; P=0.053). The incidence of high-level DSA-DRB1, however, was significantly higher in the AFG than that in the CG (40% vs. 4%; P<0.001), but there was no significant difference in DSA-DQB1 or DSA-DRB345. High-level anti-AT1R Ab was significantly more frequent in the AFG than in the CG (65% vs. 36%; P=0.02). All patients with both high-level DSA-DRB1 and high-level anti-AT1R Ab were found to have advanced fibrosis (P<0.001). CONCLUSION: Anti-AT1R Ab and DSA-DRB1 may be candidates as biomarkers of graft fibrosis; both HLA and non-HLA immunity may be involved in graft fibrosis after IS withdrawal.

Antibodies against "DANGER" in the dynamic of post-transplant circulation.

Evidence that has accumulated about the impact of non-human leukocyte antigen (HLA) antibodies against tissue-restricted antigens supports the concept that humoral targets can be constantly altered by transplant-associated stresses such as ischemia-reperfusion (IR) injury, organ preservation, immunosuppressive drugs, and pre-existing diseases. This accounts for the growing interest in "danger" signals--in the form of damage-induced molecules--expanding our understanding of the humoral cause of allograft rejection and failure from thinking it is caused only by genetically determined HLA mismatches to seeing the role played by antibody recognition of antigens modified posttransplant. The heterogeneous repertoire of antibodies was evidenced by the recent protein microarray analysis that revealed increased posttransplant levels of heterogeneous antibodies against the targets localized in specific kidney compartments. Antibodies can also be developed against molecules dynamically generated in the circulation as damage-associated molecular patterns (DAMPs) that are the endogenous version of exogenous pathogen-associated molecular patterns (PAMPs). Antibodies against some DAMP molecules have been identified in many autoimmune diseases, but mostly have been elusive in transplant immunology. Those humoral DAMP targets include the well-studied high-mobility group box 1, IR injury-induced proteins, and oxidation-specific epitopes exposed on oxidized low-density lipoprotein. Moreover, understanding the intersection of endogenous DAMPs and exogenous PAMPs in transplant immunology may reveal a new aspect of humoral reactions. Recently reported cross-recognition by polyreactive antibodies of apoptotic cells may be one of many unidentified recognition patterns that indicate existence of an immune system strategy for defending against a number of stress-induced targets as a set of "danger." Given all these findings, the recent approach of identifying disease-specific panels of up-regulated proteins may help link them with pathogenic antibodies from the pool of heterogeneous antibodies whose pathological roles have remained unidentified, helping us understand the effect of those antibodies-and vice versa, helping us understand the impact of disease-specific antigens, not just up-regulated antigens, as a cause of humoral reactions.

Predicting operational tolerance in pediatric living-donor liver transplantation by absence of HLA antibodies.

BACKGROUND: The role of anti-human leukocyte antigen (HLA) antibodies in operational tolerance (OT) after pediatric living-donor liver transplantation (LDLT) remains inconclusive. We investigated whether the presence of HLA antibodies impeded the development of OT. METHODS: We retrospectively examined the prevalence of anti-HLA antibodies in pediatric LDLT recipients before transplantation and at 3 weeks after transplantation and analyzed the significance of those antibodies in relation to later OT. Forty pediatric LDLTs were performed between April 1996 and December 2000 and followed up through July 2011, with sera available for measurement of HLA antibodies. Seventeen patients achieved OT (mean follow-up, 4571.9±544.7 days) and 23 patients did not achieve OT (mean follow-up, 4532.0±425.4 days). Protocol liver biopsy was done for 14 OT patients and 16 non-OT patients. Their sera were tested for anti-HLA class I and II antibodies using the LABScreen single antigen beads test, in which a 1000 mean fluorescence value was considered positive. RESULTS: The prevalence of antibodies after transplantation in non-OT patients was higher than in OT patients (95.2% vs. 73.3%; P<0.001). The highest mean fluorescence intensity of antibodies was significantly higher in non-OT patients than in OT patients. The prevalence of HLA-B, HLA-C, HLA-DQ, and HLA-DR antibodies was significantly higher in non-OT patients than in OT patients. The highest mean fluorescence intensity of HLA-A, HLA-B, and HLA-DQ observed in non-OT patients was significantly higher than those in OT patients. CONCLUSIONS: In our study, posttransplantation HLA antibodies were associated with the future absence of OT. A prospective study with more patients is necessary to confirm the predictive value of HLA antibodies for OT.

Donor-specific human leukocyte antigen antibodies of the immunoglobulin G3 subclass are associated with chronic rejection and graft loss after liver transplantation.

In a previous study, we found that 92% of patients with chronic rejection had donor-specific human leukocyte antigen antibodies (DSAs), but surprisingly, 61% of comparator patients without rejection also had DSAs. We hypothesized that immunoglobulin G (IgG) subclasses were differentially distributed between the 2 groups. A modified single-antigen bead assay was used to detect the presence of individual IgG subclasses against human leukocyte antigen in 39 chronic rejection patients and 66 comparator patients. DSAs of the IgG1 subclass were most common and were found in 45% of all patients; they were followed by IgG3 DSAs (21%), IgG4 DSAs (14%), and IgG2 DSAs (13%). The percentage of patients with multiple IgG subclasses was significantly higher in the chronic rejection group versus the comparator group (50% versus 14%, P < 0.001). Patients with normal graft function in the presence of DSAs mostly had isolated IgG1, whereas patients with chronic rejection had a combination of IgG subclasses. Patients who developed DSAs of the IgG3 subclass showed an increased risk of graft loss (hazard ratio = 3.35, 95% confidence interval = 1.39-8.05) in comparison with patients with DSAs of other IgG subclasses or without DSAs. Although further study is needed, the determination of the IgG subclass in DSA-positive patients may help us to identify patients with a higher risk of chronic rejection and graft loss.

Liver transplantation in the MELD era--analysis of the OPTN/UNOS registry.

OVERVIEW OF THE MODEL FOR END-STAGE LIVER DISEASE (MELD): MELD has been successful in its initial aim of reducing pre-transplant mortality by better organ allocation; at the same time, it generated a new challenge of achieving better posttransplant outcomes by adjusting the hierarchy of allocation to sicker patients. Our analysis of 49,867 adult patients in the MELD era (2002 through 2011) showed a change in the dynamics of the transplant population: the number of patients with higher priority (MELD-exception patients and high-MELD patients) has been progressively increasing while the number of those without priority has remained constant or has been decreasing depending on their disease. The re-transplantation rate has been increasing for high-MELD patients. An increase in number has also observed of major racial groups other than Whites. Overall graft survival-including that for re-transplant-has improved, regardless of MELD levels, during the decade since MELD implementation in 2002. 2. MELD WITH PRIMARY DISEASES: Over the past two decades, the incidence of hepatitis C virus (HCV) has been increasing, and after the inception of MELD, hepatocellular carcinoma (HCC) and non-alcoholic liver disease (NASH) have been progressively increasing. There appears to be a general tendency toward lower graft survival in high-MELD patients in both deceased- and living-donor transplantation. However, this trend differed among the 12 primary diseases, in which significantly lower graft survival was observed in high-MELD patients with alcoholic liver disease (ALD), NASH, autoimmune disorders (AI), HCV, hepatitis B virus (HBV) or non-HCC cancers. Overall, HCV seropositive patients had lower graft survival than HCV seronegative patients. This was also true in each high- and low-MELD group. However, analysis of the primary diseases showed four patterns for the impact of HCV seropositivity related to MELD levels: lower graft survival with anti-HCV regardless of MELD level (with acute hepatic failure, metabolic disorders and HBV); no correlation between the impact of HCV antibodies and MELD levels (with primary biliary cirrhosis [PBC], primary sclerosing cholangitis [PSC] and HCC); lowest graft survival with high MELD scores in the presence of HCV antibodies (with AI, ALD and NASH); and worse survival without HCV (non-HCC cancers). 3. MELD EXCEPTION: Among the primary diseases, the five with a high rate of HCC exception (> 70%) were HCC, HCV, HBV, ALD and AI; the four with a high rate of non-HCC exception (> 60%) were non-HCC cancers, PSC, PBC, and "Others." HCC patients with HCC-exception appear to have derived a greater benefit from transplantation, with better graft survival, than HCC patients without exception. The same beneficial effect of non-HCC exception has been observed with non-HCC cancers, the majority of them cholangiocarcinoma.

HLA-E monoclonal antibodies recognize shared peptide sequences on classical HLA class Ia: relevance to human natural HLA antibodies.

The non-classical HLA-Ib molecule, HLA-E share several peptide sequence similarities with the heavy chains of classical HLA class Ia (-B and -C) molecules. Therefore, the antibodies to HLA-E, that recognize shared sequences, may bind to HLA-Ia alleles. This hypothesis is tested by examining the affinity of HLA-E monoclonal antibodies (HLA-E-MAbs) to HLA-Ia molecules and by inhibiting the antibody binding to both HLA-E and HLA-Ia with the shared peptide sequence(s). Single recombinant HLA molecule-coated beads are used for antibody binding. The antibody binding is evaluated by measuring mean fluorescence index [MFI] with Luminex multiplex flow-cytometric technology. The peptide-inhibition experiments are carried out with synthetic shared peptides, most prevalent to HLA-E and HLA-Ia alleles. The number of HLA-Ia alleles recognized by the HLA-E-MAbs varies with the density of the antigen (quantity of antigen-coated beads) and dilution of MAb. Binding of HLA-E-MAbs to beta2 microglobulin (beta(2)m)-free HLA-Ia antigens confirms the location of the epitopes on the heavy chain (HC) of the antigens. Strikingly, the nature of alleles of HLA-Ia recognized by different HLA-E-MAbs is identical. The binding of HLA-E-MAbs to the HLA-Ia is inhibited dosimetrically by the adjacent peptides, (115)QFAYDGKDY(123) and (137)DTAAQI(142), but not by (126)LNEDLRSWTA(135), another closer shared peptide sequence. The inhibitory peptide sequences in HLA-E are at the alpha2-helix terminal facing beta(2)m. The HLA-Ia alleles recognized by HLA-E-MAb (e.g., MEM-E/02) are similar to those recognized by the natural anti-HLA antibodies found in the sera of healthy non-alloimmunized males. This study postulates that some, if not all, of the natural HLA-Ia antibodies seen in healthy males could be anti-HLA-E antibodies cross-reacting with HLA-Ia alleles.

KIR3DL1/S1 genotypes and KIR2DS4 allelic variants in the AB KIR genotypes are associated with Plasmodium-positive individuals in malaria infection.

The importance of innate immunity in malaria has been suggested for early protection from maturation and multiplication of Plasmodium parasites injected via infected mosquitoes. In this study, the killer cell immunoglobulin-like receptor (KIR) genes in innate immunity were investigated for an association with malaria in the comparison between Plasmodium-positive and Plasmodium-negative Melanesian individuals in the Solomon Islands, one of the most hyperendemic malaria regions in the world. The higher frequency of a pair of KIR3DL1 and KIR2DS4 was observed in the Plasmodium-positive individuals, which led to the investigation of KIR3DL1/S1 genotypes in concert with KIR2DS4 allelic variants. The positive individuals showed the highest frequency of KIR3DL1/KIR3DS1 heterozygosity, which might suggest the masking of activating KIR3DS1 by inhibitory KIR3DL1 at allelic levels to maintain the KIR3DS1-driven activation of natural killer cells diminished in controlling Plasmodium proliferation. The extended analysis with A/B genotypes further revealed the trend of parasitic positive individuals to be KIR3DL1/KIR3DS1 heterozygous in pair with KIR2DS4 nondeleted variants in a set of KIR genes inheritable as the AB genotypes. To the best of our knowledge, this study is the first KIR investigation of the malaria-infected population, which strengthened the potential associations of KIR with malaria pathogenesis. The balance of inhibitory and activating KIR3D genes (KIR3DL1/S1) and membrane-bound or secreted status of KIR2DS4 alleles in the interaction with the other KIR genes in the AB genotypes might constitute a part of KIR characteristics to determine resistance or susceptibility to Plasmodium parasitic infection.