Base-Edited CAR7 T Cells for Relapsed T-Cell Acute Lymphoblastic Leukemia.

BACKGROUND: Cytidine deamination that is guided by clustered regularly interspaced short palindromic repeats (CRISPR) can mediate a highly precise conversion of one nucleotide into another - specifically, cytosine to thymine - without generating breaks in DNA. Thus, genes can be base-edited and rendered inactive without inducing translocations and other chromosomal aberrations. The use of this technique in patients with relapsed childhood T-cell leukemia is being investigated. METHODS: We used base editing to generate universal, off-the-shelf chimeric antigen receptor (CAR) T cells. Healthy volunteer donor T cells were transduced with the use of a lentivirus to express a CAR with specificity for CD7 (CAR7), a protein that is expressed in T-cell acute lymphoblastic leukemia (ALL). We then used base editing to inactivate three genes encoding CD52 and CD7 receptors and the ß chain of the αß T-cell receptor to evade lymphodepleting serotherapy, CAR7 T-cell fratricide, and graft-versus-host disease, respectively. We investigated the safety of these edited cells in three children with relapsed leukemia. RESULTS: The first patient, a 13-year-old girl who had relapsed T-cell ALL after allogeneic stem-cell transplantation, had molecular remission within 28 days after infusion of a single dose of base-edited CAR7 (BE-CAR7). She then received a reduced-intensity (nonmyeloablative) allogeneic stem-cell transplant from her original donor, with successful immunologic reconstitution and ongoing leukemic remission. BE-CAR7 cells from the same bank showed potent activity in two other patients, and although fatal fungal complications developed in one patient, the other patient underwent allogeneic stem-cell transplantation while in remission. Serious adverse events included cytokine release syndrome, multilineage cytopenia, and opportunistic infections. CONCLUSIONS: The interim results of this phase 1 study support further investigation of base-edited T cells for patients with relapsed leukemia and indicate the anticipated risks of immunotherapy-related complications. (Funded by the Medical Research Council and others; ISRCTN number, ISRCTN15323014.).

CD19/CD22 targeting with cotransduced CAR T cells to prevent antigen-negative relapse after CAR T-cell therapy for B-cell ALL.

ABSTRACT: CD19-negative relapse is a leading cause of treatment failure after chimeric antigen receptor (CAR) T-cell therapy for acute lymphoblastic leukemia. We investigated a CAR T-cell product targeting CD19 and CD22 generated by lentiviral cotransduction with vectors encoding our previously described fast-off rate CD19 CAR (AUTO1) combined with a novel CD22 CAR capable of effective signaling at low antigen density. Twelve patients with advanced B-cell acute lymphoblastic leukemia were treated (CARPALL [Immunotherapy with CD19/22 CAR Redirected T Cells for High Risk/Relapsed Paediatric CD19+ and/or CD22+ Acute Lymphoblastic Leukaemia] study, NCT02443831), a third of whom had failed prior licensed CAR therapy. Toxicity was similar to that of AUTO1 alone, with no cases of severe cytokine release syndrome. Of 12 patients, 10 (83%) achieved a measurable residual disease (MRD)-negative complete remission at 2 months after infusion. Of 10 responding patients, 5 had emergence of MRD (n = 2) or relapse (n = 3) with CD19- and CD22-expressing disease associated with loss of CAR T-cell persistence. With a median follow-up of 8.7 months, there were no cases of relapse due to antigen-negative escape. Overall survival was 75% (95% confidence interval [CI], 41%-91%) at 6 and 12 months. The 6- and 12-month event-free survival rates were 75% (95% CI, 41%-91%) and 60% (95% CI, 23%-84%), respectively. These data suggest dual targeting with cotransduction may prevent antigen-negative relapse after CAR T-cell therapy.

Publisher Correction: Whole-genome sequencing of a sporadic primary immunodeficiency cohort.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Whole-genome sequencing of a sporadic primary immunodeficiency cohort.

Primary immunodeficiency (PID) is characterized by recurrent and often life-threatening infections, autoimmunity and cancer, and it poses major diagnostic and therapeutic challenges. Although the most severe forms of PID are identified in early childhood, most patients present in adulthood, typically with no apparent family history and a variable clinical phenotype of widespread immune dysregulation: about 25% of patients have autoimmune disease, allergy is prevalent and up to 10% develop lymphoid malignancies1-3. Consequently, in sporadic (or non-familial) PID genetic diagnosis is difficult and the role of genetics is not well defined. Here we address these challenges by performing whole-genome sequencing in a large PID cohort of 1,318 participants. An analysis of the coding regions of the genome in 886 index cases of PID found that disease-causing mutations in known genes that are implicated in monogenic PID occurred in 10.3% of these patients, and a Bayesian approach (BeviMed4) identified multiple new candidate PID-associated genes, including IVNS1ABP. We also examined the noncoding genome, and found deletions in regulatory regions that contribute to disease causation. In addition, we used a genome-wide association study to identify loci that are associated with PID, and found evidence for the colocalization of-and interplay between-novel high-penetrance monogenic variants and common variants (at the PTPN2 and SOCS1 loci). This begins to explain the contribution of common variants to the variable penetrance and phenotypic complexity that are observed in PID. Thus, using a cohort-based whole-genome-sequencing approach in the diagnosis of PID can increase diagnostic yield and further our understanding of the key pathways that influence immune responsiveness in humans.

The Human Phenotype Ontology in 2024: phenotypes around the world.

The Human Phenotype Ontology (HPO) is a widely used resource that comprehensively organizes and defines the phenotypic features of human disease, enabling computational inference and supporting genomic and phenotypic analyses through semantic similarity and machine learning algorithms. The HPO has widespread applications in clinical diagnostics and translational research, including genomic diagnostics, gene-disease discovery, and cohort analytics. In recent years, groups around the world have developed translations of the HPO from English to other languages, and the HPO browser has been internationalized, allowing users to view HPO term labels and in many cases synonyms and definitions in ten languages in addition to English. Since our last report, a total of 2239 new HPO terms and 49235 new HPO annotations were developed, many in collaboration with external groups in the fields of psychiatry, arthrogryposis, immunology and cardiology. The Medical Action Ontology (MAxO) is a new effort to model treatments and other measures taken for clinical management. Finally, the HPO consortium is contributing to efforts to integrate the HPO and the GA4GH Phenopacket Schema into electronic health records (EHRs) with the goal of more standardized and computable integration of rare disease data in EHRs.

Socioeconomic and Demographic Risk Factors for SARS-CoV-2 Seropositivity Among Healthcare Workers in a UK Hospital: A Prospective Cohort Study.

BACKGROUND: To protect healthcare workers (HCWs) from the consequences of disease due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is necessary to understand the risk factors that drive exposure and infection within hospitals. Insufficient consideration of key socioeconomic variables is a limitation of existing studies that can lead to bias and residual confounding of proposed risk factors for infection. METHODS: The Co-STARs study prospectively enrolled 3679 HCWs between April 2020 and September 2020. We used multivariate logistic regression to comprehensively characterize the demographic, occupational, socioeconomic, and environmental risk factors for SARS-CoV-2 seropositivity. RESULTS: After adjusting for key confounders, relative household overcrowding (odds ratio [OR], 1.4 [95% confidence interval {CI}, 1.1-1.9]; P = .006), Black, Black British, Caribbean, or African ethnicity (OR, 1.7 [95% CI, 1.2-2.3]; P = .003), increasing age (ages 50-60 years: OR, 1.8 [95% CI, 1.3-2.4]; P < .001), lack of access to sick pay (OR, 1.8 [95% CI, 1.3-2.4]; P < .001). CONCLUSIONS: Socioeconomic and demographic factors outside the hospital were the main drivers of infection and exposure to SARS-CoV-2 during the first wave of the pandemic in an urban pediatric referral hospital. Overcrowding and out-of-hospital SARS-CoV-2 contact are less amenable to intervention. However, lack of access to sick pay among externally contracted staff is more easily rectifiable. Our findings suggest that providing easier access to sick pay would lead to a decrease in SARS-CoV-2 transmission and potentially that of other infectious diseases in hospital settings. CLINICAL TRIALS REGISTRATION: NCT04380896.

Autologous Ex Vivo Lentiviral Gene Therapy for Adenosine Deaminase Deficiency.

BACKGROUND: Severe combined immunodeficiency due to adenosine deaminase (ADA) deficiency (ADA-SCID) is a rare and life-threatening primary immunodeficiency. METHODS: We treated 50 patients with ADA-SCID (30 in the United States and 20 in the United Kingdom) with an investigational gene therapy composed of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with a self-inactivating lentiviral vector encoding human ADA. Data from the two U.S. studies (in which fresh and cryopreserved formulations were used) at 24 months of follow-up were analyzed alongside data from the U.K. study (in which a fresh formulation was used) at 36 months of follow-up. RESULTS: Overall survival was 100% in all studies up to 24 and 36 months. Event-free survival (in the absence of reinitiation of enzyme-replacement therapy or rescue allogeneic hematopoietic stem-cell transplantation) was 97% (U.S. studies) and 100% (U.K. study) at 12 months; 97% and 95%, respectively, at 24 months; and 95% (U.K. study) at 36 months. Engraftment of genetically modified HSPCs persisted in 29 of 30 patients in the U.S. studies and in 19 of 20 patients in the U.K. study. Patients had sustained metabolic detoxification and normalization of ADA activity levels. Immune reconstitution was robust, with 90% of the patients in the U.S. studies and 100% of those in the U.K. study discontinuing immunoglobulin-replacement therapy by 24 months and 36 months, respectively. No evidence of monoclonal expansion, leukoproliferative complications, or emergence of replication-competent lentivirus was noted, and no events of autoimmunity or graft-versus-host disease occurred. Most adverse events were of low grade. CONCLUSIONS: Treatment of ADA-SCID with ex vivo lentiviral HSPC gene therapy resulted in high overall and event-free survival with sustained ADA expression, metabolic correction, and functional immune reconstitution. (Funded by the National Institutes of Health and others; ClinicalTrials.gov numbers, NCT01852071, NCT02999984, and NCT01380990.).

Autosomal Dominant STAT6 Gain of Function Causes Severe Atopy Associated with Lymphoma.

The transcription factor STAT6 (Signal Transducer and Activator of Transcription 6) is a key regulator of Th2 (T-helper 2) mediated allergic inflammation via the IL-4 (interleukin-4) JAK (Janus kinase)/STAT signalling pathway. We identified a novel heterozygous germline mutation STAT6 c.1255G > C, p.D419H leading to overactivity of IL-4 JAK/STAT signalling pathway, in a kindred affected by early-onset atopic dermatitis, food allergy, eosinophilic asthma, anaphylaxis and follicular lymphoma. STAT6 D419H expression and functional activity were compared with wild type STAT6 in transduced HEK293T cells and to healthy control primary skin fibroblasts and peripheral blood mononuclear cells (PBMC). We observed consistently higher STAT6 levels at baseline and higher STAT6 and phosphorylated STAT6 following IL-4 stimulation in D419H cell lines and primary cells compared to wild type controls. The pSTAT6/STAT6 ratios were unchanged between D419H and control cells suggesting that elevated pSTAT6 levels resulted from higher total basal STAT6 expression. The selective JAK1/JAK2 inhibitor ruxolitinib reduced pSTAT6 levels in D419H HEK293T cells and patient PBMC. Nuclear staining demonstrated increased STAT6 in patient fibroblasts at baseline and both STAT6 and pSTAT6 after IL-4 stimulation. We also observed higher transcriptional upregulation of downstream genes (XBP1 and EPAS1) in patient PBMC. Our study confirms STAT6 gain of function (GOF) as a novel monogenetic cause of early onset atopic disease. The clinical association of lymphoma in our kindred, along with previous data linking somatic STAT6 D419H mutations to follicular lymphoma suggest that patients with STAT6 GOF disease may be at higher risk of lymphomagenesis.245 words.

Immunotherapy with CD25/CD71-allodepleted T cells to improve T-cell reconstitution after matched unrelated donor hematopoietic stem cell transplant: a randomized trial.

BACKGROUND AIMS: Delayed immune reconstitution is a major challenge after matched unrelated donor (MUD) stem cell transplant (SCT). In this randomized phase 2 multi-center trial, Adoptive Immunotherapy with CD25/71 allodepleted donor T cells to improve immunity after unrelated donor stem cell transplant (NCT01827579), the authors tested whether allodepleted donor T cells (ADTs) can safely be used to improve immune reconstitution after alemtuzumab-based MUD SCT for hematological malignancies. METHODS: Patients received standard of care or up to three escalating doses of ADTs generated through CD25+/CD71+ immunomagnetic depletion. The primary endpoint of the study was circulating CD3+ T-cell count at 4 months post-SCT. Twenty-one patients were treated, 13 in the ADT arm and eight in the control arm. RESULTS: The authors observed a trend toward improved CD3+ T-cell count at 4 months in the ADT arm versus the control arm (230/µL versus 145/µL, P = 0.18), and three ADT patients achieved normal CD3+ T-cell count at 4 months (>700/µL). The rates of significant graft-versus-host disease (GVHD) were comparable in both cohorts, with grade ≥2 acute GVHD in seven of 13 and four of eight patients and chronic GVHD in three of 13 and three of eight patients in the ADT and control arms, respectively. CONCLUSIONS: These data suggest that adoptive transfer of ADTs is safe, but that in the MUD setting the benefit in terms of T-cell reconstitution is limited. This approach may be of more use in the context of more rigorous T-cell depletion.

Recommendations for uniform definitions used in newborn screening for severe combined immunodeficiency.

BACKGROUND: Public health newborn screening (NBS) programs continuously evolve, taking advantage of international shared learning. NBS for severe combined immunodeficiency (SCID) has recently been introduced in many countries. However, comparison of screening outcomes has been hampered by use of disparate terminology and imprecise or variable case definitions for non-SCID conditions with T-cell lymphopenia. OBJECTIVES: This study sought to determine whether standardized screening terminology could overcome a Babylonian confusion and whether improved case definitions would promote international exchange of knowledge. METHODS: A systematic literature review highlighted the diverse terminology in SCID NBS programs internationally. While, as expected, individual screening strategies and tests were tailored to each program, we found uniform terminology to be lacking in definitions of disease targets, sensitivity, and specificity required for comparisons across programs. RESULTS: The study's recommendations reflect current evidence from literature and existing guidelines coupled with opinion of experts in public health screening and immunology. Terminologies were aligned. The distinction between actionable and nonactionable T-cell lymphopenia among non-SCID cases was clarified, the former being infants with T-cell lymphopenia who could benefit from interventions such as protection from infections, antibiotic prophylaxis, and live-attenuated vaccine avoidance. CONCLUSIONS: By bringing together the previously unconnected public health screening community and clinical immunology community, these SCID NBS deliberations bridged the gaps in language and perspective between these disciplines. This study proposes that international specialists in each disorder for which NBS is performed join forces to hone their definitions and recommend uniform registration of outcomes of NBS. Standardization of terminology will promote international exchange of knowledge and optimize each phase of NBS and follow-up care, advancing health outcomes for children worldwide.

Curation and expansion of Human Phenotype Ontology for defined groups of inborn errors of immunity.

BACKGROUND: Accurate, detailed, and standardized phenotypic descriptions are essential to support diagnostic interpretation of genetic variants and to discover new diseases. The Human Phenotype Ontology (HPO), extensively used in rare disease research, provides a rich collection of vocabulary with standardized phenotypic descriptions in a hierarchical structure. However, to date, the use of HPO has not yet been widely implemented in the field of inborn errors of immunity (IEIs), mainly due to a lack of comprehensive IEI-related terms. OBJECTIVES: We sought to systematically review available terms in HPO for the depiction of IEIs, to expand HPO, yielding more comprehensive sets of terms, and to reannotate IEIs with HPO terms to provide accurate, standardized phenotypic descriptions. METHODS: We initiated a collaboration involving expert clinicians, geneticists, researchers working on IEIs, and bioinformaticians. Multiple branches of the HPO tree were restructured and extended on the basis of expert review. Our ontology-guided machine learning coupled with a 2-tier expert review was applied to reannotate defined subgroups of IEIs. RESULTS: We revised and expanded 4 main branches of the HPO tree. Here, we reannotated 73 diseases from 4 International Union of Immunological Societies-defined IEI disease subgroups with HPO terms. We achieved a 4.7-fold increase in the number of phenotypic terms per disease. Given the new HPO annotations, we demonstrated improved ability to computationally match selected IEI cases to their known diagnosis, and improved phenotype-driven disease classification. CONCLUSIONS: Our targeted expansion and reannotation presents enhanced precision of disease annotation, will enable superior HPO-based IEI characterization, and hence benefit both IEI diagnostic and research activities.

Long-Term Persistence of Spike Protein Antibody and Predictive Modeling of Antibody Dynamics After Infection With Severe Acute Respiratory Syndrome Coronavirus 2.

BACKGROUND: Antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been shown to neutralize the virus in vitro and prevent disease in animal challenge models on reexposure. However, the current understanding of SARS-CoV-2 humoral dynamics and longevity is conflicting. METHODS: The COVID-19 Staff Testing of Antibody Responses Study (Co-Stars) prospectively enrolled 3679 healthcare workers to comprehensively characterize the kinetics of SARS-CoV-2 spike protein (S), receptor-binding domain, and nucleoprotein (N) antibodies in parallel. Participants screening seropositive had serial monthly serological testing for a maximum of 7 months with the Meso Scale Discovery Assay. Survival analysis determined the proportion of seroreversion, while 2 hierarchical gamma models predicted the upper and lower bounds of long-term antibody trajectory. RESULTS: A total of 1163 monthly samples were provided from 349 seropositive participants. At 200 days after symptoms, >95% of participants had detectable S antibodies, compared with 75% with detectable N antibodies. S antibody was predicted to remain detectable in 95% of participants until 465 days (95% confidence interval, 370-575 days) using a "continuous-decay" model and indefinitely using a "decay-to-plateau" model to account for antibody secretion by long-lived plasma cells. S-antibody titers were correlated strongly with surrogate neutralization in vitro (R2 = 0.72). N antibodies, however, decayed rapidly with a half-life of 60 days (95% confidence interval, 52-68 days). CONCLUSIONS: The Co-Stars data presented here provide evidence for long-term persistence of neutralizing S antibodies. This has important implications for the duration of functional immunity after SARS-CoV-2 infection. In contrast, the rapid decay of N antibodies must be considered in future seroprevalence studies and public health decision-making. This is the first study to establish a mathematical framework capable of predicting long-term humoral dynamics after SARS-CoV-2 infection. CLINICAL TRIALS REGISTRATION: NCT04380896.

Patients with XLP type 1 have variable numbers of NKT cells.

X-linked lymphoproliferative disease (XLP1) is a rare primary immunodeficiency that usually presents in early childhood. Patients with XLP1 have been reported to have absent NKT cells, and it has been suggested that this can be diagnostic for the disorder. Whilst NKT frequency in adults is variable, little is known about their frequency in children. Therefore, we established a paediatric reference range for these cells. In contrast to previous reports, in our cohort of XLP1 patients, NKT cell numbers were found to be variable, and we would advise against using the finding of NKT cells to exclude a diagnosis of XLP1.

Diagnosis of HLH: two siblings, two distinct genetic causes.

This report highlights case of two siblings who developed haemophagocytic lymphohystiocytosis due to distinct genetic abnormalities. Though their presentation was clinically similar, the cases demonstrate that a shared genetic diagnosis among siblings cannot be assumed.

T cell responses to SARS-CoV-2 in healthy controls and primary immunodeficiency patients.

Understanding the T cell response to SARS-CoV-2 is key in patients who lack antibody production. We demonstrate the applicability of a functional assay to measure the T cell response in a cohort of patients with immunodeficiency.

High Prevalence of Hemophagocytic Lymphohistiocytosis in Acute Liver Failure of Infancy.

OBJECTIVES: To investigate the prevalence of hemophagocytic lymphohistiocytosis (HLH) syndrome in pediatric acute liver failure (PALF) of infancy and assess the diagnostic role of rapid immunologic tests, genotype/phenotype correlations, and clinical outcomes. STUDY DESIGN: We retrospectively analyzed 78 children with PALF aged <24 months referred over almost 2 decades. The studied patients with a phenotype of HLH syndrome had a comprehensive immunologic workup, including additional genetic analysis for primary immunologic causes. RESULTS: Thirty of the 78 children had the HLH phenotype and underwent genetic assessment, which demonstrated positive findings in 19 (63.3%), including 9 (30%) with biallelic primary HLH mutations and 10 (33.3%) with heterozygous mutations and/or polymorphisms. The most common form of primary HLH was familial hemophagocytic lymphohistiocytosis (FHL)-2, diagnosed in 6 children, 4 of whom had a c.50delT (p.Leu17ArgfsTer34) mutation in the PRF1 gene. Three patients with primary HLH received genetic diagnoses of FHL-3, Griscelli syndrome, and LRBA (lipopolysaccharide-responsive vesicle trafficking, beach- and anchor-containing) protein deficiency. Overall mortality in the series was 52.6% (10 of 19), and mortality in children with a documented biallelic pathogenic HLH mutation (ie, primary HLH) was 66.6% (6 of 9). Two children underwent liver transplantation, and 4 children underwent emergency hematopoietic stem cell transplantation; all but 1 child survived medium term. CONCLUSIONS: Primary HLH can be diagnosed retrospectively in approximately one-third of infants with indeterminate PALF (iPALF) who meet the clinical criteria for HLH, often leading to their death. The most common HLH type in iPALF is FHL-2, caused by biallelic mutations in PRF-1. The clinical relevance of observed heterozygous mutations and variants of uncertain significance requires further investigation. Prompt hematopoietic stem cell transplantation could be life-saving in infants who survive the liver injury.

Key diagnostic markers for autoimmune lymphoproliferative syndrome with molecular genetic diagnosis.

Autoimmune lymphoproliferative syndrome (ALPS) is a rare immunodeficiency caused by mutations in genes affecting the extrinsic apoptotic pathway (FAS, FASL, CASP10). This study evaluated the clinical manifestations, laboratory findings, and molecular genetic results of 215 patients referred as possibly having ALPS. Double-negative T-cell (DNT) percentage and in vitro apoptosis functional tests were evaluated by fluorescence-activated cell sorting; interleukin 10 (IL-10) and IL-18 and soluble FAS ligand (sFASL) were measured by enzyme-linked immunosorbent assay. Genetic analysis was performed by next-generation sequencing. Clinical background data were collected from patients' records. Patients were categorized into definite, suspected, or unlikely ALPS groups, and laboratory parameters were compared among these groups. Of 215 patients, 38 met the criteria for definite ALPS and 17 for suspected ALPS. The definite and suspected ALPS patient populations showed higher DNT percentages than unlikely ALPS and had higher rates of lymphoproliferation. Definite ALPS patients had a significantly more abnormal in vitro apoptosis function, with lower annexin, than patients with suspected ALPS (P = .002) and patients not meeting ALPS criteria (P < .001). The combination of elevated DNTs and an abnormal in vitro apoptosis functional test was the most useful in identifying all types of ALPS patients; the combination of an abnormal in vitro apoptosis functional test and elevated sFASLs was a predictive marker for ALPS-FAS group identification. Lymphoproliferation, apoptosis functional test, and DNTs are the most sensitive markers; elevated IL-10 and IL-18 are additional indicators for ALPS. The combination of elevated sFASLs and abnormal apoptosis function was the most valuable prognosticator for patients with FAS mutations.

Clinical and immunological features in a cohort of patients with partial DiGeorge syndrome followed at a single center.

DiGeorge syndrome (DGS) is a primary immunodeficiency characterized by various degrees of T-cell deficiency. In partial DGS (pDGS), other risk factors could predispose to recurrent infections, autoimmunity, and allergy. The aim of this study was to assess the effect of different factors in the development of infections, autoimmunity, and/or allergy in patients with pDGS. We studied 467 pDGS patients in follow-up at Great Ormond Street Hospital. Using a multivariate approach, we observed that palatal anomalies represent a risk factor for the development of recurrent otitis media with effusion. Gastroesophageal reflux/dysphagia and asthma/rhinitis represent a risk factor for the development of recurrent upper respiratory tract infections. Allergy and autoimmunity were associated with persistently low immunoglobulin M levels and lymphopenia, respectively. Patients with autoimmunity showed lower levels of CD3+, CD3+CD4+, and naïve CD4+CD45RA+CD27+ T lymphocytes compared with pDGS patients without autoimmunity. We also observed that the physiological age-related decline of the T-cell number was slower in pDGS patients compared with age-matched controls. The age-related recovery of the T-cell number depended on a homeostatic peripheral proliferation of T cells, as suggested by an accelerated decline of the naïve T lymphocytes in pDGS as well as a more skewed T-cell repertoire in older pDGS patients. These evidences suggest that premature CD4+ T-cell aging and lymphopenia induced spontaneous peripheral T-cell proliferation might contribute to the pathogenesis of autoimmunity in patients with pDGS. Infections in these patients represent, in most of the cases, a complication of anatomical or gastroenterological anomalies rather than a feature of the underlying immunodeficiency.

Comparability of six different immunoassays measuring SARS-CoV-2 antibodies with neutralizing antibody levels in convalescent plasma: From utility to prediction.

BACKGROUND: Convalescent plasma (CP) therapy for coronavirus disease (COVID-19) provides virus-neutralizing antibodies that may ameliorate the outcome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. The effectiveness of CP likely depends on its antiviral neutralizing potency and is determined using in vitro neutralizing antibody assays. STUDY DESIGN AND METHODS: We evaluated abilities of three immunoassays for anti-spike antibodies (EUROimmun, Ortho, Roche), a pseudotype-based neutralization assay, and two assays that quantify ACE2 binding of spike protein (GenScript and hemagglutination test [HAT]-based assay) to predict neutralizing antibody titers in 113 CP donations. Assay outputs were analyzed through linear regression and calculation of sensitivities and specificities by receiver operator characteristic (ROC) analysis. RESULTS: Median values of plasma samples containing neutralizing antibodies produced conversion factors for assay unitage of ×6.5 (pseudotype), ×19 (GenScript), ×3.4 (HAT assay), ×0.08 (EUROimmun), ×1.64 (Roche), and ×0.10 (Ortho). All selected assays were sufficient in identifying the high titer donations based on ROC analysis; area over curve ranged from 91.7% for HAT and GenScript assay to 95.6% for pseudotype assay. However, their ability to predict the actual neutralizing antibody levels varied substantially as shown by linear regression correlation values (from 0.27 for Ortho to 0.61 for pseudotype assay). DISCUSSION: Overall, the study data demonstrate that all selected assays were effective in identifying donations with high neutralizing antibody levels and are potentially suitable as surrogate assays for donation selection for CP therapy.

T cell phenotype in paediatric heart transplant recipients.

Paediatric heart transplantation recipients suffer an increased incidence of infectious, autoimmune and allergic problems. The relative roles of thymus excision and immunosuppressive treatments in contributing to these sequelae are not clear. We compared the immunological phenotypes of 25 heart transplant recipients (Tx), 10 children who underwent thymus excision during non-transplantation cardiac surgery (TE) and 25 age range-matched controls, in two age bands: 1-9 and 10-16 years. Significant differences from controls were seen mainly in the younger age band with Tx showing lower CD3 and CD4 cell counts whilst TE showed lower CD8 cell counts. Naïve T cell and recent thymic emigrant proportions and counts were significantly lower than controls in both groups in the lower age band. T cell recombination excision circle (TREC) levels were lower than controls in both groups in both age bands. There were no differences in regulatory T cells, but in those undergoing thymus excision in infancy, their proportions were higher in TE than Tx, a possible direct effect of immunosuppression. T cell receptor V beta spectratyping showed fewer peaks in both groups than in controls (predominantly in the older age band). Thymus excision in infancy was associated with lower CD8 cell counts and higher proportions of Tregs in TE compared to Tx. These data are consistent with thymus excision, particularly in infancy, being the most important influence on immunological phenotype after heart transplantation.