HLA Class I Genotype Is Associated with Relapse Risk after Allogeneic Stem Cell Transplantation for NPM1-Mutated Acute Myeloid Leukemia.

Mutation-bearing peptide ligands from mutated nucleophosmin-1 (NPM1) protein have been empirically found to be presented by HLA class I in acute myeloid leukemia (AML). We hypothesized that HLA genotype may impact allogeneic hematopoietic stem cell transplantation (allo-HCT) outcomes in NPM1-mutated AML owing to differences in antigen presentation. We evaluated the effect of the variable of predicted strong binding to mutated NPM1 peptides using HLA class I genotypes from matched donor-recipient pairs on transplant recipients' overall survival (OS) and disease-free survival (DFS) as part of the primary objectives and cumulative incidence of relapse and nonrelapse mortality (NRM) as part of secondary objectives. Baseline and outcome data reported to the Center for International Blood and Marrow Transplant Research from a study cohort of adult patients (n = 1020) with NPM1-mutated de novo AML in first (71%) or second (29%) complete remission undergoing 8/8 matched related (18%) or matched unrelated (82%) allo-HCT were analyzed retrospectively. Class I alleles from donor-recipient pairs were analyzed for predicted strong HLA binding to mutated NPM1 using netMHCpan 4.0. A total of 429 (42%) donor-recipient pairs were classified as having predicted strong-binding HLA alleles (SBHAs) to mutated NPM1. In multivariable analyses adjusting for clinical covariates, the presence of predicted SBHAs was associated with a lower risk of relapse (hazard ratio [HR], .72; 95% confidence interval [CI], .55 to .94; P = .015). OS (HR, .81; 95% CI, .67 to .98; P = .028) and DFS (HR, .84; 95% CI, .69 to 1.01; P = .070) showed a suggestion of better outcomes if predicted SBHAs were present but did not meet the prespecified P value of <.025. NRM did not differ (HR, 1.04; P = .740). These hypothesis-generating data support further exploration of HLA genotype-neoantigen interactions in the allo-HCT context.

Deceased-Donor Acute Kidney Injury and Acute Rejection in Kidney Transplant Recipients: A Multicenter Cohort.

RATIONALE & OBJECTIVE: Donor acute kidney injury (AKI) activates innate immunity, enhances HLA expression in the kidney allograft, and provokes recipient alloimmune responses. We hypothesized that injury and inflammation that manifested in deceased-donor urine biomarkers would be associated with higher rates of biopsy-proven acute rejection (BPAR) and allograft failure after transplantation. STUDY DESIGN: Prospective cohort. SETTING & PARTICIPANTS: 862 deceased donors for 1,137 kidney recipients at 13 centers. EXPOSURES: We measured concentrations of interleukin 18 (IL-18), kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) in deceased donor urine. We also used the Acute Kidney Injury Network (AKIN) criteria to assess donor clinical AKI. OUTCOMES: The primary outcome was a composite of BPAR and graft failure (not from death). A secondary outcome was the composite of BPAR, graft failure, and/or de novo donor-specific antibody (DSA). Outcomes were ascertained in the first posttransplant year. ANALYTICAL APPROACH: Multivariable Fine-Gray models with death as a competing risk. RESULTS: Mean recipient age was 54 ± 13 (SD) years, and 82% received antithymocyte globulin. We found no significant associations between donor urinary IL-18, KIM-1, and NGAL and the primary outcome (subdistribution hazard ratio [HR] for highest vs lowest tertile of 0.76 [95% CI, 0.45-1.28], 1.20 [95% CI, 0.69-2.07], and 1.14 [95% CI, 0.71-1.84], respectively). In secondary analyses, we detected no significant associations between clinically defined AKI and the primary outcome or between donor biomarkers and the composite outcome of BPAR, graft failure, and/or de novo DSA. LIMITATIONS: BPAR was ascertained through for-cause biopsies, not surveillance biopsies. CONCLUSIONS: In a large cohort of kidney recipients who almost all received induction with thymoglobulin, donor injury biomarkers were associated with neither graft failure and rejection nor a secondary outcome that included de novo DSA. These findings provide some reassurance that centers can successfully manage immunological complications using deceased-donor kidneys with AKI.

Incidence of acute rejection and patient survival in combined heart-liver transplantation.

Combined heart-liver transplantation (CHLT) is indicated for patients with concomitant end-stage heart and liver disease or patients with amyloid heart disease where liver transplantation mitigates progression. Limited data suggest that the liver allograft provides immunoprotection for heart and kidney allografts in combined transplantation from the same donor. We hypothesized that CHLT reduces the incidence of acute cellular rejection (ACR) and the development of de novo donor-specific antibodies (DSAs) compared with heart-alone transplantation (HA). We conducted a retrospective analysis of 32 CHLT and 280 HA recipients in a single-center experience. The primary outcome was incidence of ACR based on protocol and for-cause myocardial biopsy. Rejection was graded by the International Society of Heart and Lung Transplantation guidelines with Grade 2R and higher considered significant. Secondary outcomes included the development of new DSAs, cardiac function, and patient and cardiac graft survival rates. Of CHLT patients, 9.7% had ACR compared with 45.3% of HA patients (p < 0.01). Mean pretransplant calculated panel reactive antibody (cPRA) levels were similar between groups (CHLT 9.4% vs. HA 9.5%; p = 0.97). Among patients who underwent testing, 26.9% of the CHLT and 16.7% of HA developed DSA (p = 0.19). Despite the difference in ACR, patient and cardiac graft survival rates were similar at 5 years (CHLT 82.1% vs. HA 80.9% [p = 0.73]; CHLT 82.1% vs. HA 80.9% [p = 0.73]). CHLT reduced the incidence of ACR in the cardiac allograft, suggesting that the liver offers immunoprotection against cellular mechanisms of rejection without significant impacts on patient and cardiac graft survival rates. CHLT did not reduce the incidence of de novo DSA, possibly portending similar long-term survival among cardiac allografts in CHLT and HA.

BLyS neutralization results in selective anti-HLA alloantibody depletion without successful desensitization.

Pre-existing anti-HLA allo-antibodies (allo-Abs) are a major barrier to successful kidney transplantation, resulting in an elevated risk for antibody-mediated rejection (AMR) and eventual graft loss. The cytokine B lymphocyte stimulator (BLyS) promotes B cell maturation and plasma cell survival; consequently, anti-BLyS therapy represents a potential therapeutic opportunity in diminishing pre-existing allo-Abs. Here we report that in our 1-year pilot trial, BLyS neutralization failed to reduce total anti-HLA allo-Ab levels in highly sensitized candidates awaiting kidney transplant in a clinically meaningful way. Additionally, we performed a post hoc analysis using sera from trial candidates which revealed selective depletion of anti-HLA class I and class II Abs in response to belimumab treatment, restricted to certain allele specificities and IgG subclasses. Altogether, we observed that BLyS blockade only results in selective depletion of anti-HLA Abs recognizing a few discrete HLA allele specificities.

Genetics of HLA Peptide Presentation and Impact on Outcomes in HLA-Matched Allogeneic Hematopoietic Cell Transplantation.

Minor histocompatibility antigens (mHAs), recipient-derived peptide epitopes presented on the cell surface, are known to mediate graft-versus-host disease (GVHD); however, there are no current methods to associate mHA features with GVHD risk. This deficiency is due in part to the lack of technological means to accurately predict, let alone confirm, the tremendous number of potential mHAs in each individual transplant. Previous studies have shown that different HLA molecules present varying fractions of candidate peptide epitopes; however, the genetic "distance" between HLA-matched donors and recipients is relatively constrained. From these 2 observations, it is possible that the HLA type for a donor-recipient pair (DRP) would provide a surrogate measurement of the number of predicted mHAs, which could be related to GVHD risk. Because different HLA molecules present variable numbers of peptide antigens, a predicted cumulative peptide-binding efficiency can be calculated for individual DRP based on the pair's HLA type. The purpose of this study was to test whether cumulative peptide-binding efficiency is associated with the risk of acute GVHD (aGVHD) or relapse. In this retrospective Center for International Blood and Marrow Transplant Research study, a total of 3242 HLA-matched DRPs were analyzed for predicted cumulative peptide-binding efficiency using their HLA types and were divided into tertiles based on their scores. Univariable and multivariable analyses was performed to test for associations between cumulative peptide-binding efficiency for DRPs, divided into the HLA-matched related donor (MRD) and HLA-matched unrelated donor (MUD) cohorts, and the primary outcomes of aGVHD and relapse. Secondary outcomes investigated included overall survival, disease-free survival, and transplantation-related mortality. Using a computationally generated peptidome as a test dataset, the tested series of HLA class I displayed peptide-binding frequencies ranging from 0.1% to 3.8% of the full peptidome, and HLA class II molecules had peptide-binding frequencies of 12% to 77% across the HLA-DRB1 allotypes. By increasing binding efficiency tertile, the cumulative incidence of aGVHD at 6 months for MUD patients was 41%, 41%, and 45% for HLA class I (P = .336) and 44%, 41%, and 42% for HLA class II (P = .452). The cumulative incidences of relapse at 3 years for MUD transplant recipients were 36%, 38%, and 38% for HLA class I (P = .533) and 37%, 37%, and 38% for HLA class II (P = .896). The findings were similar for MRD transplant recipients. Multivariable analysis did not identify any impact of peptide-binding efficiency on aGVHD or relapse in MUD or MRD transplant recipients. Whereas GVHD is mediated by minor antigen mismatches in the context of HLA-matched allo-HCT, peptide-binding efficiency, which was used as a surrogate measurement for predicted number of binding antigens, did not provide additional clinical information for GVHD risk assessment. The negative result may be due to the limitations of this surrogate marker, or it is possible that GVHD is driven by a subset of immunogenic mHAs. Further research should be directed at direct mHA epitope and immunogenicity prediction.

Specific Class I HLA Supertypes but Not HLA Zygosity or Expression Are Associated with Outcomes following HLA-Matched Allogeneic Hematopoietic Cell Transplant: HLA Supertypes Impact Allogeneic HCT Outcomes.

Maximizing the probability of antigen presentation to T cells through diversity in HLAs can enhance immune responsiveness and translate into improved clinical outcomes, as evidenced by the association of heterozygosity and supertypes at HLA class I loci with improved survival in patients with advanced solid tumors treated with immune checkpoint inhibitors. We investigated the impact of HLA heterozygosity, supertypes, and surface expression on outcomes in adult and pediatric patients with acute myeloid leukemia (AML), myelodysplastic syndrome, acute lymphoblastic leukemia, and non-Hodgkin lymphoma who underwent 8/8 HLA-matched, T cell replete, unrelated, allogeneic hematopoietic cell transplant (HCT) from 2000 to 2015 using patient data reported to the Center for International Blood and Marrow Transplant Research. HLA class I heterozygosity and HLA expression were not associated with overall survival, relapse, transplant-related mortality (TRM), disease-free survival (DFS), and acute graft-versus-host disease following HCT. The HLA-B62 supertype was associated with decreased TRM in the entire patient cohort (hazard ratio [HR], 0.79; 95% CI, 0.69 to 0.90; P = .00053). The HLA-B27 supertype was associated with worse DFS in patients with AML (HR = 1.21; 95% CI, 1.10 to 1.32; P = .00005). These findings suggest that the survival benefit of HLA heterozygosity seen in solid tumor patients receiving immune checkpoint inhibitors does not extend to patients undergoing allogeneic HCT. Certain HLA supertypes, however, are associated with TRM and DFS, suggesting that similarities in peptide presentation between supertype members play a role in these outcomes. Beyond implications for prognosis following HCT, these findings support the further investigation of these HLA supertypes and the specific immune peptides important for transplant outcomes.

The impact of HLA-DR mismatch status on retransplant-free survival and bronchiolitis obliterans syndrome‒free survival among sensitized lung transplant recipients.

INTRODUCTION: Donor‒recipient HLA-DR locus matching may be protective against bronchiolitis obliterans syndrome (BOS) in lung transplant recipients. It is unknown whether this benefit is more significant among sensitized (calculated panel reactive antibodies (CPRAs) of >0%) and highly sensitized (CPRAs of ≥80%) recipients who may be at a higher risk for BOS. METHODS: This was a retrospective cohort study of adults in the Scientific Registry of Transplant Recipients who underwent lung transplantation between May 5, 2005 and May 31, 2019. Retransplant-free survival and BOS-free survival were compared among recipients with 0 vs ≥1 DR mismatches, grouped according to sensitization. RESULTS: Among all 20,355 included recipients, 0 DR mismatch status was associated with improved retransplant-free survival (hazard ratio [HR] = 0.83, 95% CI = 0.74-0.93, p = 0.002) and BOS-free survival (HR = 0.86, 95% CI = 0.77-0.96, p = 0.007). Among sensitized recipients, 0 DR mismatch status was also associated with improved retransplant-free survival (HR = 0.79, 95% CI = 0.65-0.97, p = 0.02) and BOS-free survival (HR = 0.82, 95% CI = 0.67-1.00, p = 0.04). There was however no difference in retransplant-free or BOS-free survival between sensitized and non-sensitized recipients with 0 DR mismatches. Among highly sensitized recipients, 0 DR mismatch status was not associated with retransplant-free or BOS-free survival. Among sensitized and highly sensitized recipients, 0 DR mismatch status was not associated with reduced use of plasmapheresis or reduced biopsy-proven, treated acute cellular rejection compared with non-sensitized recipients. CONCLUSIONS: HLA-DR matching is associated with a similar improvement in retransplant-free and BOS-free survival among non-sensitized and sensitized lung transplant recipients. DR matching does not confer a more substantial retransplant-free or BOS-free survival benefit to highly sensitized recipients than to non-sensitized recipients.

Class and Kinetics of Weakly Reactive Pretransplant Donor-specific HLA Antibodies Predict Rejection in Kidney Transplant Recipients.

BACKGROUND: The clinical impact of weakly reactive pretransplant donor-specific antibody (DSA) in kidney transplantation is controversial. While some evidence suggests that weakly reactive DSA can lead to rejection, it is unclear which patients are at risk for rejection and whether posttransplant changes in weakly reactive DSA are clinically meaningful. METHODS: We retrospectively studied 80 kidney transplant recipients with weakly reactive pretransplant DSA between 2007 and 2014. We performed a multivariate Cox regression analysis to identify immunologic factors most associated with risk of biopsy-proven rejection. RESULTS: Biopsy-proven rejection occurred in 13 of 80 (16%) patients. The presence of both class I and II DSA before transplant (hazards ratio 17.4, P < 0.01) and any posttransplant increase in DSA reactivity above a mean fluorescence intensity of 3000 (hazards ratio 7.8, P < 0.01) were each significantly associated with an increased risk of rejection, which primarily occurred within the first 18 months. CONCLUSIONS: Pretransplant DSA class and DSA kinetics after transplantation are useful prognostic indicators in patients with weak DSA reactivity. These results identify a small, high-risk patient group that warrants aggressive posttransplant DSA monitoring and may benefit from alternative donor selection.

Improving the antibody-based evaluation of autoimmune encephalitis.

OBJECTIVE: We tested whether antibody screening samples of patients with suspected autoimmune encephalitis with additional research assays would improve the detection of autoimmune encephalitis compared with standard clinical testing alone. METHODS: We examined 731 samples (333 CSF, 182 sera, and 108 pairs) from a cohort of 623 patients who were tested for CNS autoantibodies by the University of Pennsylvania clinical laboratory over a 24-month period with cell-based assays (CBAs) on commercially obtained slides of fixed cells for antibodies to NMDA receptor (NMDAR), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), γ-aminobutyric acid-B receptor (GABABR), leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (Caspr2), and glutamic acid decarboxylase (GAD65). In parallel, our research laboratory screened all samples for reactivity to brain sections and for anti-NMDAR using in-house CBAs. Samples with brain reactivity or positive clinical studies were examined with CBAs for a larger panel of antibodies. RESULTS: The clinical laboratory reported positive findings for NMDAR (80 samples), GAD65 (8), LGI1 (5), Caspr2 (2), and GABABR (4). Sixty-five serum samples and 32 CSF samples were indeterminate for one or more antibodies. In our research laboratory, all but 4 positive results were confirmed, 88 of 97 indeterminate results were resolved, and 15 additional samples were found positive (10 NMDAR, 1 AMPAR, 3 LGI1, and 1 Caspr2). Clinical information supported these diagnoses. Overall, informative autoantibodies were detected in 15.5% of cases. CONCLUSIONS: Standard clinical laboratory kits were specific, but some tests were insensitive and prone to indeterminate results. Screening with immunohistochemistry for reactivity to brain sections, followed by additional CBAs for cases with brain reactivity, improves the diagnostic accuracy of testing for autoimmune encephalitis.

Histopathologic changes in anti-angiotensin II type 1 receptor antibody-positive kidney transplant recipients with acute rejection and no donor specific HLA antibodies.

OBJECTIVE: To determine the association of antibodies against angiotensin II type 1 receptor (AT1R Ab) and histopathologic changes seen in patients with kidney allograft rejection and negative donor specific HLA antibodies (DSA). METHODS: Stored sera from 27 patients who had biopsy-proven rejection in the absence of DSA were tested for AT1R Ab. Biopsy slides of all patients were re-examined and classified according to Banff 2013 criteria. Histopathologic changes were compared between AT1R positive and negative patients. RESULTS: 75% of patients with positive pre-transplant AT1R Ab had antibody mediated rejection (AMR) compared to 37% of AT1R Ab-negative patients. A trend towards increased interstitial inflammation was observed in the AT1R Ab positive group (p=0.08). More patients in the AT1R Ab positive group had microcirculation inflammation (88% vs 58% with glomerulitis scores ≥1; 75% vs 58% with peritubular capillaritis scores ≥1). CONCLUSION: In kidney transplant recipients with rejection and no DSA, a higher incidence of AMR and worse inflammation scores are observed in the presence of positive pre-transplant AT1R antibodies.

Correlation of Circulating Complement-Fixing Donor-Specific Antibodies Identified by the C1q Assay and Presence of C4d in Endomyocardial Biopsy Specimens.

OBJECTIVES: Donor-specific antibodies (DSAs) are associated with increased cardiac graft loss. We applied a C1q solid-phase assay in parallel with the standard immunoglobulin G (IgG) single antigen bead (SAB) assay to examine the correlation of circulating complement-fixing donor-specific antibodies and the presence of C4d in endomyocardial biopsy (EMB) specimens. METHODS: We retrospectively studied the relationship of C1q+ DSAs and C4d immunofluorescence (IF) in 49 EMB specimens from 44 heart transplant recipients who had concurrent EMB, C4d IF, and DSA measurements. We applied a C1q SAB in parallel with the standard IgG SAB assay to examine the DSA profiles in heart transplant patients posttransplant. RESULTS: A better concordance is observed between C1q+ DSAs with C4d IF+ compared with IgG DSAs with C4d IF + (40% vs 24%, P = .02). However, the correlation of C1q DSAs with C4d IF is not statistically significant (P = .24). Importantly, C1q+ DSAs were observed in 16 of 17 cases with C4d IF+; 24 cases had circulating C1q+ DSAs without detectable C4d staining, suggesting that that the presence of C1q+ DSAs may precede the detection of C4d deposition in EMB specimens and/or the development of antibody-mediated rejection. CONCLUSIONS: In this cohort of 44 patients, no significant correlation was observed between circulating C1q DSAs and C4d IF in EMB specimens. Additional studies are needed to further evaluate the association of C1q DSAs with EMB specimens and C4d staining.

Correlations of lymphocyte subset infiltrates with donor-specific antibodies and acute antibody-mediated rejection in endomyocardial biopsies.

BACKGROUND: Acute antibody-mediated rejection (AMR) is a major complication after heart transplantation, posing a significant risk for allograft failure, cardiac allograft vasculopathy, and poor survival. While the inflammatory milieu of cellular rejection and Quilty lesions is well known, the immunologic components of AMR are not well understood. Our aim was to better define the immunophenotype of infiltrating lymphocytes in biopsies with AMR, specifically in relation to donor-specific antibodies to human leukocyte antigen (HLA) class I, II, or both. METHOD: We performed a retrospective analysis of cardiac transplant patients with concurrent endomyocardial biopsies (EMB), donor-specific antibody (DSA) measurements, and immunofluorescence for C4d at our institution (2005-2011). DSA was evaluated against HLA class I and class II specificities pre- and posttransplant using flow cytometry and/or Luminex bead assays. Acute cellular rejection (ACR) and pathologic AMR (pAMR) were based on the International Society for Heart and Lung Transplantation 2005/2013 reports. Immunohistochemical analysis for CD3, CD4, CD8, and CD79a was performed using standard immunohistochemical protocols on one formalin-fixed, paraffin-embedded EMB from each patient. The number of lymphocytes expressing each protein was enumerated microscopically at 400×. Ratios of T:B cells and CD4:CD8 T cells were then calculated for each EMB. RESULTS: Seventy-nine cardiac transplant patients who had pre- and posttransplant DSA measurements were analyzed. Of these 79 patients, 37 had DSA against HLA class I, HLA class II, or both. Of patients with DSA, the average CD4:CD8 ratio in the EMB was 0.80, while those with only ACR had a CD4:CD8 ratio of 1.49. Interestingly, the T:B cell ratio in patients with and without DSA was 5.7 and 5.5, respectively. CONCLUSION: Cardiac transplant patients with DSA against HLA have more CD8 cytotoxic T cells than CD4 helper T cells in the EMB lymphocytic infiltrate compared with patients without DSA against HLA. The inflammatory infiltrate T:B cell ratio was similar in patients both with and without DSA. The relative increase of cytotoxic T cells in EMB while the patient has DSA suggests a possible pathogenic role of these cells and may aid in the diagnosis and treatment of AMR.

Transplant nephrectomy: histologic findings­a single center study.

AIMS: To identify the histopathological features of transplant nephrectomy (TN) specimens. METHODS: We performed retrospective analysis of 73 nephrectomies to review the histopathology in detail and correlate the Banff grading characteristics of TN specimens with time post engraftment and clinical features. Retrospective data on donor-specific antibodies (DSA) were also collected. RESULTS: The majority of patients who had TN in less than 3 months posttransplant (n = 20; median time to TN: 4 days) had hemorrhagic infarction; 7 patients (35%) had grade 3 acute rejection (AR). Patients who had TN later than 3 months posttransplant (n = 53; median time to TN: 67 months) had AR, grade 2B (21%) and 3 (43%), coexisting with advanced vascular injury in the form of interstitial hemorrhage, extensive interstitial fibrosis and tubular atrophy (IF/TA) as well as the presence of DSAs. Overall, the majority of patients without DSA pre-TN developed DSA post-TN. CONCLUSIONS: Our data revealed extensive inflammation and ongoing immunologic activity in a subset of patients with a failed graft. Careful and individualized approach based on clinical and laboratory data should guide the decision for transplant nephrectomy.

Circulating donor-specific anti-human leukocyte antigen antibodies and complement C4d deposition are associated with the development of cardiac allograft vasculopathy.

BACKGROUND: Cardiac allograft vasculopathy (CAV) continues to be a limiting factor in long-term survival of heart transplant recipients (HTRs). Pathophysiologic and immunologic factors affecting CAV are complex, and criteria for early diagnosis remain elusive. METHODS: We performed a retrospective analysis of the relationship between donor-specific antibody (DSA), C4d immunofluorescence, and the development of CAV. RESULTS: We evaluated 330 endomyocardial biopsy (EMB) specimens from 112 cardiac grafts. Twenty-four (21%) of 112 grafts developed CAV, and 18 (75%) of 24 were positive for C4d. Patients with DSA (n = 51) against human leukocyte antigen class I (n = 5), II (n = 26), or both (n = 20) developed CAV at a rate of 40%, 38%, and 20% and a mean time to CAV of 89, 47, and 25 months, respectively. Of 61 grafts without DSA, only 13% developed CAV, with a mean time to CAV of 116 months. CONCLUSIONS: Compared with the general HTR population, patients with graft dysfunction and DSA or positive C4d on EMB show a statistically significant increased incidence of CAV and allograft failure, suggesting an antibody-mediated injury. The presence of pre- and posttransplant DSA, even in the absence of positive C4d immunofluorescence, may identify a group of HTRs at increased risk of developing CAV.

Profound hyperacute cardiac allograft rejection rescue with biventricular mechanical circulatory support and plasmapheresis, intravenous immunoglobulin, and rituximab therapy.

Hyperacute rejection is a rare but potentially catastrophic complication after cardiac transplantation. We describe an unusual case of hyperacute rejection due to preformed anti-donor antibodies despite a negative preoperative panel-reactive antibody (PRA) screen. An excellent outcome was achieved in this case and our strategy involving the use of CentriMag ventricular assist devices (VADs) for biventricular support during treatment with rituximab, intravenous immunoglobulin (IVIG), and plasmapheresis is illustrated.

Correlation of circulating donor-specific anti-HLA antibodies and presence of C4d in endomyocardial biopsy with heart allograft outcomes: a single-center, retrospective study.

BACKGROUND: Donor-specific antibodies (DSA) are associated with increased cardiac graft loss and cardiac vasculopathy (CAV). Detection of antibody-mediated rejection (AMR) relies on graft dysfunction, C4d immunofluorescence (IF) and DSA. METHODS: We retrospectively studied the relationship of DSA, endomyocardial biopsy (EMB) and C4d IF to cardiac transplant outcomes. DSA were evaluated against HLA class I and II specificities, both pre- and post-transplant, using microbead-based assays. RESULTS: Of 626 cardiac transplant patients, 109 with concurrent EMBs and C4d IF and DSA measurement were included in this study. In patients with and without DSA, CAV occurred in 31% and 13% and acute cellular rejection (ACR) in 100% and 84%, respectively. One hundred ten of 170 EMBs procured during episodes of graft dysfunction had concurrent DSA. In these patients, C4d IF correlated better with DSA to class I or both class I and II and less so in patients with DSA to class II. Graft failure (GF) rates of 40%, 29% and 58% with average times to GF of 33, 77 and 48 months were seen in patients with DSA to class I, II or both, respectively. CONCLUSIONS: Patients with DSA to class I or to both class I and II showed a correlation with C4d IF and had higher GF rates compared to patients with DSA to only class II or no DSA; patients with DSA to class II remained at risk for CAV. Episodes of ACR and CAV, but not AMR, appeared to be more frequently associated with graft dysfunction in patients with circulating DSA.

Antibody-mediated rejection in heart transplant patients: long-term follow up of patients with high levels of donor-directed anti-DQ antibodies.

Antibody-mediated rejection (AMR) is a complication of orthotopic heart transplantation. There is no standard for treatment and it is unclear what role monitoring of donor-directed antibodies (DSA) should play in guiding treatment decisions. In this case series, we describe three patients transplanted at our center who developed AMR and received rituximab as one component of the treatment regimen. We found in these three patients that despite clinical resolution of AMR, high levels of class II donor-directed antibodies persisted. We also summarize our retrospective analysis of 110 heart allografts that had pre- and post-transplant DSA measurements with corresponding EMB and immunofluorescence (IF) during 2005-2011. Our analysis of a subpopulation of 50 informative patients (with DSA measurements, EMB, and corresponding IF) revealed that moderate and severe cardiac allograft vasculopathy were identified more frequently in grafts with DSA than compared to those without DSA.

Progressive multifocal leukoencephalopathy in a patient with common variable immunodeficiency and abnormal CD8+ T-cell subset distribution.

BACKGROUND: Patients with primary hypogammaglobulinemia have been reported to have encephalopathy, but progressive multifocal leukoencephalopathy (PML) due to JC virus reactivation is a rare cause. OBJECTIVE: To provide the clinical details and case discussion of a patient diagnosed as having common variable immunodeficiency (CVID) who has progressive neurodegenerative symptoms and was found to have PML and an abnormal CD8+ T-cell subset distribution. METHODS: A detailed case report providing the patient's immunodeficiency history, diagnostic evaluation, and medical management and a review of related literature. RESULTS: Before his neurodegenerative illness, the patient was found to have hypogammaglobulinemia, poor specific antibody responses, low circulating B-cell levels, and abnormal delayed-type hypersensitivity responses; there was no Bruton tyrosine kinase (BTK) mutation. The PML was diagnosed using brain biopsy and was confirmed using a DNA probe specific for JC virus. Peripheral blood flow cytometry at the time of PML diagnosis revealed an accumulation of naive CD8+ T cells (CD3+CD8+CD45RA+) and a deficiency of memory CD8+ T-cell subsets (CD3+CD8+CD45RA- or CD3+CD8+CD45RO+). Despite aggressive treatment with interleukin 2, interferon-gamma, and intravenous cidofovir, the patient died. CONCLUSIONS: JC virus infection should be considered in the differential diagnosis of the patient with CVID and signs and symptoms of encephalopathy. The role of this patient's abnormal CD8' T-cell subset distribution in the development or control of this rare infection is worthy of consideration and has encouraged us to enumerate naive and memory CD4+ and CD8+ T-cell subsets in patients diagnosed as having CVID, even in the absence of neurodegenerative symptoms.

Analysis of the CD2 and spliceosomal Sm B/B' polyproline-arginine motifs defined by a monoclonal antibody using a phage-displayed random peptide library.

The cytoplasmic region of the CD2 receptor of lymphocytes contains proline-rich motifs, which are involved in T cell activation and interleukin-2 production. An intracellular CD2 binding protein, CD2BP2, interacts with two tandem PPPPGHR segments of the CD2 tail. CD2BP2 contains a GYF (glycine-tyrosine-phenylalanine) domain that confers binding to these proline-rich sequences. Monoclonal antibody 3E10 that was previously raised against a peptide containing the CD2 PPPPGHR segment reacts with the native CD2 molecule and spliceosomal Sm B/B' proteins. To identify the exact epitope on the CD2 peptide recognized by 3E10, a phage-displayed combinatorial peptide library was used. Analysis of the selected clones revealed that the mAb 3E10 binds preferentially to the motif PxxPPGxR. Experiments using amino acid substitutions with synthetic peptides confirmed the reactivity of mAb 3E10 with this motif. In addition, we show that several similarities exist between this motif and the CD2BP2-GFY recognition motif PPGxR/K. Binding of antibody 3E10 indicates some degree of degeneracy, which is consistent with its ability to recognize structurally related polyproline-arginine motifs found in intracellular proteins including Sm B/B' proteins and other RNA binding proteins. Thus, mAb 3E10 can be used to specifically identify a sub-class of proline-rich motifs, and as such can be used to study the potential role of these proline-rich sequences in mediating protein-protein interactions.