Journal of Clinical Immunology

BackgroundPost-acute COVID-19 syndrome (PACS) can cause persistent disability involving fatigue, post-exertional malaise, neurocognitive symptoms, and autonomic manifestations. A clinically overlapping condition has been reported following COVID-19 vaccination and termed post-acute COVID-19 vaccination syndrome (PACVS), but its underlying mechanisms remain poorly understood. We investigated whether immune dysregulation, autoreactivity, antigen persistence, and viral reactivation--mechanisms implicated in PACS--are also present in PACVS. MethodsThis cross-sectional study included 28 PACS patients, 29 PACVS patients, and 16 convalescent controls (CCG). Clinical manifestations were assessed using ME/CFS-related symptom questionnaires and the Bell Score. T-cell phenotypes and T cells reactive to SARS-CoV-2 Spike, {beta}1/{beta}2-adrenergic receptor, and M3/M4 muscarinic receptor antigens were analyzed by multicolor flow cytometry. Circulating Spike protein and GPCR autoantibodies were quantified by ELISA, and EBV load by qPCR. ResultsPACS and PACVS showed substantial clinical overlap, although several symptoms were more severe in PACS. GPCR autoantibody profiles were comparable between patient groups, while {beta}2-adrenergic receptor autoantibodies were increased compared with CCG. Only three of 57 conventional immunophenotyping parameters differed between PACS and PACVS in unadjusted analyses, whereas both groups showed multiple alterations compared with CCG. Circulating Spike protein was detected in both patient groups, with the highest prevalence in PACVS. {beta}1/{beta}2- and M3/M4-reactive CD4+ T cells were increased, whereas Spike-specific CD4+ T cells were reduced compared with CCG. EBV reactivation was rare. ConclusionsPACS and PACVS exhibit substantial clinical and immunological overlap, including GPCR-directed autoreactivity and altered receptor-reactive T-cell responses. These shared immune-mediated features suggest overlapping pathophysiological mechanisms and warrant investigation of whether therapeutic strategies currently explored for PACS may also be relevant to PACVS.

Partially preserved function of recombination-activating genes (RAG) 1 and 2 can be linked to divergent and hard-to-predict clinical and immunological phenotypes, even among close relatives. It is unclear how intrinsic RAG hypomorphism interacts with extrinsic environmental pressures to shape clinical trajectory. We dissect this phenomenon in a unique cohort of 18 Old Order Mennonite individuals with a novel missense founder RAG1 variant (p.C176F) with 25.8% recombinase activity of wild-type protein. After studying a myriad of markers, we demonstrate varying severity and progression of clinical disease (predominantly in females) that paralleled decline in CMV-specific immune competence, break in tolerance with hallmark presence of antibodies to IFN, a TH1/IFN{gamma}-driven inflammatory milieu with elevated serum markers (CXCL9/10), expansion of follicular helper T cells and clonal B cells enriched for autoreactive-prone VH4.34 B cell receptor. BCR and TCR repertoires carry the fingerprints of both extrinsic and RAG-driven intrinsic changes. Through this experiment of nature, our cohort demonstrated that partial RAG deficiency (pRD) is not a monolithic disease but the result of compounded RAG intrinsic and extrinsic events. Overall, this study uses multi-omics approaches to dissect the contribution of a hypomorphic RAG variant to variable severity of clinical disease and immunological dysregulation at cellular and molecular level. Emerging biomarkers of a multi-omic roadmap should allow monitoring of progression of clinical disease and guide who and when to treat with hematopoietic stem cell transplant in pRD.

Sickle cell disease (SCD) results from homozygosity or compound heterozygosity for a single point mutation in the beta hemoglobin gene. Despite carrying the same underlying causal mutation, patients exhibit highly heterogeneous clinical outcomes. Acute chest syndrome (ACS) is one of the leading causes of mortality in SCD. In this study, we aimed to identify genetic variants associated with ACS occurrence and recurrence (>5 episodes) in two SCD cohorts (OMG-SCD and Walk-PHaSST) of predominantly African ancestry and characterize their downstream molecular consequences. Although none of the SNPs reached the genome-wide threshold in the occurrence meta-analysis, we identified 40 independent genetic loci with p <10-5. However, the recurrence GWAS in OMG-SCD, which compared individuals with no prior history of ACS to individuals with a history of >5 episodes, identified one genome-wide significant locus along with 38 other independent loci with p <10-5. Survival analysis suggested lower survival probability among young ACS recurrence cases compared to controls or occurrence cases. Furthermore, molecular QTL analysis of ACS recurrence identified 42 SNP-protein and eight SNP-metabolite associations with p <10-3. Pathway and enrichment analysis identified secretory, platelet/hemostatic, and complement-mediated pathways, confirming the complex and heterogeneous pathophysiology of ACS. This study highlights the importance of a well-defined phenotype for identification of risk loci and elucidates the complex interplay of hemolytic, inflammatory, and cellular organization pathways that warrants further evaluation through large-scale multi-omic studies of SCD patients. Ultimately, the more extreme phenotype of ACS recurrence may be a more informative phenotype for analysis, risk prediction, and therapeutic targeting.

Background: Common variable immunodeficiency is frequently underrecognized due to its heterogeneous clinical presentation, resulting in diagnostic delays that increase disease-related complications, with each year of delay increasing mortality risk by 4% for the most common inborn error of immunity. Objective: In individuals with established common variable immunodeficiency, we sought to recognize patterns in patient diagnostic trajectories to identify opportunities for interventions to reduce time to diagnosis. Methods: We analyzed retrospective electronic health records data from 139 individuals with physician-confirmed common variable immunodeficiency across five academic health systems representing >10million patients. We evaluated diagnosing specialties and international classification of disease code trajectories in the two years prior to and at common variable immunodeficiency confirmation. Additionally, we construct specialty-specific prediction on a 1:50 case: control cohort using a gradient boosting algorithm. Results: The leading diagnoses at common variable immunodeficiency determination were respiratory (35% of individuals), and individuals with respiratory symptoms were more likely to be diagnosed by Allergy / Immunology than by other specialties (odds ratio 2.9, standard error 0.35, p-value 1.9x10-3) and had a higher frequency of visits to pulmonary disease in the two years prior to diagnosis. Individuals with neoplasms were 50% more likely than other patients (OR 2.0, SE 0.29, p-value 0.02) to receive a diagnosis at each visit, reducing their diagnostic delay by up to a year. We find that a larger ratio of number of specialties visited to the total number of visits is significantly correlated with an increased time to diagnosis. A trajectory-informed specialty-specific prediction improved detection with an area under the precision-recall curve of fifty times the value expected under the null. Conclusions: Individuals referred to Allergy / Immunology have shorter time to diagnosis, and a specialty-specific prediction could improve detection of common variable immunodeficiency. Clinical Implications: Overall, we find that phenotype-specialty interactions may inform targeted interventions to improve common variable immunodeficiency recognition across specialties, reducing diagnostic odyssey and disease-related complications.

Background: In 2026, the US Food and Drug Administration (FDA) identified uveitis as a potential signal of serious risk for the B-cell maturation antigen (BCMA) x CD3 bispecific antibodies teclistamab and elranatamab. Uveitis in this setting may reflect opportunistic infection or immune-mediated inflammation, which require opposite management. Methods: We analyzed FDA Adverse Event Reporting System (FAERS) reports from July 2020 to June 2026 (8,690,601 reports after deduplication) using a case-non-case design, calculating reporting odds ratios (RORs) and the information component for primary-suspect reports. Comparators were belantamab mafodotin, talquetamab and CD3 bispecific antibodies used outside myeloma. Every primary-suspect uveitis report (n = 76) was classified as infectious, probable immune-mediated (hereafter immune-mediated) or indeterminate by a physician blinded to a rule-based algorithm. Results: Uveitis was reported in 18 of 2,995 teclistamab and 29 of 1,691 elranatamab reports (ROR 4.10 [95% CI 2.58-6.52] and 11.85 [8.21-17.12]). Of these 47 cases, 20 were infectious (18 cytomegalovirus chorioretinitis; median onset 92 days), and infection-specified uveitis was disproportionately reported for both agents and for CD3 bispecific antibodies used outside myeloma. Thirteen were immune-mediated, arose early (median onset 4 days) and were co-reported with cytokine release syndrome in six; immune-mediated uveitis showed a signal only for elranatamab (8 cases; ROR 3.59, 1.79-7.18), not for teclistamab or any comparator. Six of the eight elranatamab cases originated from Japan. Agreement between physician and algorithm was 98.7%. Conclusions: The FDA uveitis signal appears to comprise a late infectious uveitis shared by most T-cell-redirecting bispecific antibodies examined and an early immune-mediated uveitis that showed a signal only with elranatamab. These hypothesis-generating findings support prompt ophthalmological assessment of new visual symptoms and exclusion of cytomegalovirus retinitis before corticosteroids are started.

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening thrombotic microangiopathy caused by a severe deficiency of the ADAMTS13 protease. We performed the first large-scale genome-wide association study (GWAS) of TTP in 1,344 individuals of Han Chinese ancestry, comprising a discovery cohort (n = 913) and a validation cohort (n = 431). We identified two independent susceptibility loci, including the known locus 6p21 and the novel locus 14q32. At the known locus 6p21, the lead signal rs2187668 is near HLA-DQA1 and strongly associated with TTP risk (P = 5.35e-10; Odds Ratio [OR] = 3.94). At the novel locus 14q32, the lead SNP rs1024350 (P = 1.01e-10; OR = 1.90) is located between LINC00221 and MIR5195. Fine-mapping prioritized rs2187668 as the leading signal at 6p21, whereas HLA imputation and stepwise conditional analysis further pinpointed amino acid position 74 of HLA-DRB1 as the primary driver of the broader MHC association (P = 2.28e-10), superseding classical allele-based models. Structural analysis revealed that position 74 lines pocket 4 of the HLA-DRB1 peptide-binding groove; the risk-conferring Leu/Arg residues at this position carried by HLA-DRB1*08:03 and DRB1*03 may favour presentation of ADAMTS13-derived autoantigenic peptides, whereas the common Ala residue is protective. In summary, we reconstructed the genetic architecture of TTP in East Asians and identified structural gatekeepers of autoimmunity, providing novel targets for precision medicine and ethnic-specific risk stratification.

Post-treatment Lyme disease syndrome (PTLDS) is characterized by persistent symptoms after antibiotic therapy for Borrelia burgdorferi infection. The mechanisms underlying these symptoms remain incompletely understood and have been attributed to ongoing low-level infection, autoimmunity, or immune dysregulation driven by residual bacterial antigens. We investigated whether Borrelia burgdorferi protein antigen persists in long-lived monocyte subsets in PTLDS patients and is associated with broader immune dysregulation. CD14CD16 monocytes from 10 patients with PTLDS were analyzed by mass spectrometry; plasma from all 10 was profiled on a 14-plex cytokine panel against 50 healthy donors; PBMCs from 6 patients (3 antigen-positive and 3 antigen-negative) underwent RT-qPCR and bulk RNA-seq with immune-compartment profiling. FlaB and OspC were detected in CD14CD16 monocytes months to years after treatment, whereas Borrelia burgdorferi transcript was not detected. Plasma IFN-{gamma} exceeded the healthy donor median in all 10 participants. Antigen-positive samples showed an antigen-associated inflammatory transcriptional profile, including increased TNFSF14/LIGHT, GSDMD, GBP5, and KCNJ2 expression, together with a compartment-level pattern of monocyte-skewed myeloid reconfiguration, higher neutrophil-related features, and selective T-cell-state changes. These findings link residual Borrelia burgdorferi protein in CD14CD16 monocytes to monocyte-skewed immune remodeling in PTLDS, paralleling observations in long COVID and supporting a model in which post-infectious syndromes are sustained by antigen-fueled immune remodeling rather than ongoing infection.

The non-canonical NF-kappa B pathway, in which NFKB2 plays a central role, is critical for lymphoid organ development and immune homeostasis. Pathogenic NFKB2 variants have been strongly associated with a broad spectrum of human pathologies, notably immunodysregulation syndromes, characterized by recurrent infections, autoantibody production and endocrine abnormalities. The mechanisms underlying the resulting immune defects remain incompletely understood. In the present study, we characterized the immune phenotype of a novel rat model harboring a Nfkb2 non-sense mutation located in the c-terminal region of the gene (c.2602T>A; p.Tyr867*, Nfkb2p.Tyr867*). This variant has been identified in patients with a familial form of common variable immunodeficiency (CVID) presenting with autoimmunity manifestations. Using this model, we demonstrate that mutated NFKB2 resulted in profound alterations of the thymic microenvironment, including reduced K5+ medullary thymic epithelial cells and decreased AIRE expression, accompanied by altered thymocyte development and impaired thymic regulatory T populations. Peripheral lymphoid organization was also profoundly affected, with absence of lymph nodes, defects in the splenic marginal zone, and alterations of CD4+ and CD8+ T-cell homeostasis, including impaired Treg populations and reduced ICOS expression on CD4+ T cells. The B-cell compartment was markedly altered, with impaired B-cell maturation, characterized by accumulation of IgM+IgD- transitional cells and a marked reduction of IgD+ mature B cells. These abnormalities were associated with impaired humoral immunity and complete absence of circulating immunoglobulins. Collectively, our findings define a systemic combined immunodeficiency phenotype in the Nfkb2-mutated rat, highlighting its utility for studying the role of non-canonical NF-kB signaling in immune system organization and adaptative immunity.

Neutralizing antibodies are a correlate of protection (CoP) of SARS-CoV-2 vaccine efficacy. However, data informing CoPs often explicitly exclude people on immunosuppressive therapies who are at an increased risk of symptomatic and severe COVID-19, delayed viral clearance, and death. Investigating the relationship between antibodies and protection for people on immunosuppressive therapies could provide insights into mechanisms of protection. We performed a systematic search to identify studies reporting SARS-CoV-2 binding antibody levels after mRNA vaccination in people with hematological malignancies, neurological disorders, rheumatic diseases, and mixed immune-mediated inflammatory disorders (IMIDs) on immunosuppressive therapies including B-cell depletion, JAK inhibitors, and S1P inhibitors, as well as healthy controls. Binding antibody levels varied between cohorts receiving different immunosuppressive treatments. Compared to healthy controls the lowest antibody levels were observed in subjects treated with B-cell depletion (54.5-fold reduction, 95% CI: 34.5-86.2) and S1P inhibitors (24.8-fold reduction, 95% CI: 13.2-46.7). To assess the association between antibody level and protection, we used data from a previous study of COVID-19 vaccine effectiveness in people with the same underlying conditions. We linked vaccine effectiveness estimates with the predicted antibody level in people on immunosuppressive therapies (using antibody data including this meta-analysis of binding antibody levels). Predicted neutralizing antibody levels were correlated with vaccine effectiveness both for infection and hospitalization (p<0.0001 and p<0.0001, respectively). However, we found that for any given antibody level, people who are immunosuppressed had lower protection against infection and hospitalization than a healthy population.

Background. Persistent SARS-CoV-2 antigen is a leading hypothesis for post-acute sequelae of SARS-CoV-2 infection (PASC), commonly known as Long COVID. Impaired Fc-mediated antiviral antibody function could contribute to inefficient clearance of infected cells and viral antigen despite preserved antibody levels. Therefore, we tested whether PASC is associated with altered Fc{gamma} receptor-mediated antibody function and differences in IgG1 Fc fucosylation, a major regulator of Fc effector function. Methods. Serum samples from RECOVER-Adult participants with prior SARS-CoV-2 infection (99 PASC, 139 non-PASC) were analyzed for anti-SARS-CoV-2 spike receptor-binding domain (RBD) IgG and subclasses, Fc{gamma}RIIIa- and Fc{gamma}RIIa-mediated reporter activity as surrogate measures of antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP), anti-RBD IgG1 Fc glycosylation, and circulating fucose-modifying enzymes. Results. Despite higher anti-RBD IgG and IgG1 abundance, PASC sera showed lower ADCC- and ADCP-associated Fc{gamma}R reporter activity, including after normalization for antibody abundance. Anti-RBD IgG1 showed greater fucosylation in PASC samples (30 PASC, 34 non-PASC). Serum FUCA2 was lower in PASC samples (24 PASC, 34 non-PASC), whereas FUCA1 and soluble CD16a levels did not differ between the two groups. Conclusion. PASC is associated with impaired antiviral IgG Fc function, increased IgG1 Fc fucosylation, and reduced circulating FUCA2, identifying a glycoimmune axis that may contribute to impaired Fc-dependent antigen clearance and represents a potentially targetable pathway in Long COVID.

Background: Hereditary spastic paraplegia (HSP) comprises a heterogeneous group of neurodegenerative disorders characterized by progressive lower-extremity weakness and spasticity, with or without additional neurological symptoms. Objectives: To characterize the molecular genetic spectrum, inheritance patterns, molecular finding rate, and clinical characteristics of HSP within a multicenter Canadian cohort. Methods: We investigated 671 patients from 423 families who met clinical criteria for HSP identified through the Canadian HSP (CanHSP) registry from 7 medical centers across Canada. Patients were evaluated using known HSP and HSP mimic gene panels, whereas unsolved and more recent patients underwent whole-exome sequencing (WES). 435 individuals underwent gene-panel testing and 485 underwent WES. Copy-number variants (CNVs) were assessed using ExomeDepth, and candidate CNVs using multiplex ligation-dependent probe amplification (MLPA). Results: Molecular findings were identified in 426 of 671 individuals (63.5%): 351 (52.3%) had HSP-associated findings, 70 (10.4%) HSP-mimicking disorders, and five (0.7%) other molecular findings; 245 (36.5%) remained unresolved. Candidate variants were found in 80 relevant genes, 36 of which were HSP-associated genes. The most frequently implicated genes were SPAST (22.5%), SPG7 (5.7%), ATL1 (5.2%), SPG11 (3.6%), and SPG8 (3.3%). Phenotypically, SPAST, ATL1, and SPG8 w[zg1.1]ere predominantly associated with pure HSP, whereas SPG7 and SPG11 more often showed complicated phenotypes, with prominent cerebellar involvement in SPG7 and cognitive and developmental features in SPG11. Conclusion: Patients in CanHSP present with genetic and phenotypic heterogeneity. Reanalysis and complementary approaches, including whole-genome, RNA, and long-read sequencing, may increase diagnostic yield.

Herpes zoster (HZ), caused by varicella zoster virus (VZV) reactivation, is common in older adults with declining cell-mediated immune protection. A modestly efficacious live attenuated (ZVL) and a highly efficacious recombinant adjuvanted (RZV) zoster vaccine protect against HZ. To uncover the mechanism(s) associated with the superior efficacy of RZV, we developed a controlled human infection model consisting of intradermal administration of attenuated vOka VZV to older adults previously vaccinated with RZV or ZVL. Infiltration of VZV-specific CD4+ and CD8+ T cell clonotypes at the infection site was quicker and higher in RZV than ZVL recipients [&ge;]5 years post-immunization due to the persistence of RZV-induced gE-reactive CD4+ and CD8+ T cell clonotypes in blood. High CD4+ cytotoxic T lymphocyte frequencies in blood on Day 1 post-inoculation predicted control of VZV replication. Persistence of circulating RZV-induced CD4+ and CD8+ CTL and rapid migration to sites of VZV replication are potential mechanisms underlying durable protection against HZ.

BackgroundPremature ovarian insufficiency (POI) is a condition affecting female fertility e.g., in the context of autoimmune disease. A recent proof-of-concept study showed that B-cell depletion with rituximab (RTX) temporarily restored ovarian function in patients with autoimmune POI. However, the underlying immunological mechanisms behind this response is unknown. ObjectivesTo characterize B- and T-cell phenotypes before and after RTX therapy in the above-mentioned patients and associations with autoantibody levels and treatment response. MethodsCryopreserved cell samples were available from six autoimmune patients with POI, four of whom were positive for autoantibodies against steroidogenic enzymes (21OH, 17OH and/or SCC). Patients received RTX and blood samples were collected at baseline, second infusion (2 weeks), 3, 8 and 12 months. Peripheral B- and T-cell phenotypes were analysed using spectral flow cytometry and correlated with autoantibody levels. ResultsAt baseline, patients displayed signs of B-cell activation by alteration in subset composition compared to matched controls. Upon closer analysis, patients positive for steroidogenic enzyme autoantibodies had significantly increased frequency of CXCR3+switched memory (SWM) B-cells than autoantibody-negative patients, which correlated positively with anti-17OH and-SCC autoantibody levels. In parallel, increased Th1 cell frequencies were also observed in the same patient group. Longitudinal analyses showed expected B-cell depletion followed by repopulation after RTX. Changes in T-cell subsets were observed at 8 months with reduced frequencies of Th1 and Tfh cells. ConclusionAutoimmune POI displayed altered B- and T-cell subsets implicating cell crosstalk, immune cell infiltration to sites of inflammation such as ovaries, and presence of Th1-driven immunopathogenesis. Key messagesO_LIIncreased CXCR3+SWM B cells and Th1 cells were found in patients with autoimmune POI who were positive for autoantibodies against steroidogenic enzymes. C_LIO_LICXCR3 expression on SWM B cells positively associated with anti-17OH and anti-SCC autoantibody levels. C_LIO_LIRTX induced rapid B-cell depletion followed by repopulation and a delayed T-cell effect at 8 months with reduced Th1 and Tfh cell frequencies. C_LI Capsule summaryRTX has recently been shown to restore fertility in autoimmune POI. Lymphocyte profiling identified Th1 bias accompanied by CXCR3+memory B cells that correlate with autoantibody levels. B-cell depletion appears to temporarily alleviate ovarian autoimmunity and ameliorate physiological function.

Sepsis causes approximately 11 million deaths globally each year. Whole-genome sequencing (WGS) of founder populations offers a unique opportunity for discovery of genes related to susceptibility of sepsis. We performed GWAS and EXWAS on WGS data for n=210 Arab ICU patients (n=68 sepsis cases, n=142 controls, other ICU-related disorders) and prioritized n=40 associated deleterious founder variants in n=31 genes (REGENIE Firth regression p < 0.05; CADD score > 20; enriched AAF vs AllofUs/gnomAD), including a novel start-loss variant in UBE2L3 (c.2T>G; p.Met1?; CADD = 25.6; SIFT = 0.001) in sepsis cases (3/68 vs 0/142 controls; Fisher's exact P = 0.026). In All of Us (AoU), UBE2L3 missense burden was associated with bacterial infection (n=26,939 cases; SKAT-O P = 2.38x10-3; OR=23.10; 95% CI = [0.63-845.27]). LLM AI models fine-tuned for drug development scored UBE2L3 a 7.8 of 10 as a drug target for sepsis, consistent with mouse UBE2L3 KO showing increased IL-1Beta mediated inflammation in sepsis.

Mitochondrial disease arises from variants in either the mitochondrial or nuclear genome that impair mitochondrial oxidative phosphorylation. Complex III (ubiquinol:cytochrome c oxidoreductase, CIII2) is a key enzyme of the mitochondrial respiratory chain, catalyzing electron transfer from reduced coenzyme Q10 (ubiquinol) to complex IV, via cytochrome c. CIII2 has one subunit encoded by mitochondrial DNA, the remainder being nuclear encoded. Individuals with CIII2 deficiency present with significant clinical heterogeneity, on account of pathogenic variants in genes encoding structural CIII2 subunits or assembly factors. UQCC1 (GenBank: NM_018244.5) encodes the mitochondrial complex III assembly factor Ubiquinol-cytochrome c reductase complex assembly factor 1, which is currently not associated with human disease. Here we describe nine subjects from eight unrelated families harboring biallelic UQCC1 variants with heterogeneous, early-onset mitochondrial disease presentations and lactic acidosis. Subject-derived fibroblasts demonstrated a decrease in the steady-state levels of UQCC1 and its interacting partner UQCC2, with structural modelling supportive of variant pathogenicity. BN-PAGE and quantitative proteomics demonstrated decreased CIII2 abundance whilst mass spectrometry (MS)-complexome profiling corroborated these findings, identifying impaired respiratory supercomplex formation and a delay in the incorporation of newly synthesized CIII2 subunits into native assemblies. Lentiviral transduction experiments in subject-derived fibroblasts restored the levels of both UQCC1 protein and CIII2 activity. Collectively, these findings provide convergent genetic, biochemical, proteomic and functional evidence that bi-allelic UQCC1 variants disrupt CIII2 assembly, establishing UQCC1 deficiency as a cause of mitochondrial CIII2 deficiency.

Background: Giant cell arteritis (GCA), traditionally considered T cell-driven, exhibits vascular B/plasma-cell infiltrates and altered circulating B-cell homeostasis, suggesting a pathogenic role for B cells. Relapse is common in newly diagnosed GCA (nGCA), yet predictive biomarkers remain elusive. Objective: To characterize circulating B-cell subpopulations in nGCA and assess their association with 12-month relapse. Methods: Baseline multiparametric flow cytometry was performed on peripheral blood samples from consecutive patients with nGCA and sex/age-matched healthy controls (HC). Patients received standard treatment per 2018 EULAR recommendations and were followed longitudinally. Results: 102 patients with nGCA and 102 matched HC were included. One-year outcome data were available for 55 patients, of whom 34 relapsed and 21 remained relapse-free. Baseline B-cell homeostasis differed by disease course. Non-relapsers showed reduced total CD19+ B-cell counts and contraction of most B-cell subsets, while CD27-IgD-double-negative (DN) B-cell counts remained comparable to HC. Conversely, relapsers maintained total B-cell numbers above HC despite reduced memory compartments, driven by expanded naive and DN B cells, alongside preserved plasmablast and transitional B-cell counts. At 6 months, total B-cell counts increased only in non-relapsers. DN B cells showed the greatest divergence between groups and independently predicted relapse. DN B-cell counts also correlated with circulating T peripheral helper cell numbers, supporting extrafollicular immune pathway activation. Conclusion: nGCA is characterized by outcome-dependent disturbances in B-cell homeostasis. Expansion of the DN B-cell compartment identifies a relapse-prone immunophenotype and represents a clinically relevant biomarker for early risk stratification.

FBXO31 encodes the substrate receptor of an SCF (SKP1-CUL1-F-box) E3 ubiquitin ligase that recognizes C-terminal amide-bearing proteins (CTAPs) and targets them for proteasomal degradation, a function of particular importance in neurons. A recurrent de novo missense variant, c.1000G>A p.(Asp334Asn), reprograms FBXO31 substrate specificity and causes an autosomal-dominant neurodevelopmental disorder with spastic cerebral palsy through a neomorphic gain-of-function mechanism. By contrast, biallelic loss of function has tentatively been linked to a recessive disorder. Here we report a female patient, born to consanguineous parents, with moderate intellectual disability, developmental delay and dysmorphic features, who carries a homozygous 54.3 kb deletion removing exons 2-8 and the coding part of exon 9 of FBXO31. The deletion retains only the exon 1-encoded F-box domain, while removing the coding sequence for the entire C-terminal substrate-recognition region. It is predicted to result in loss of function. Segregation is consistent with autosomal-recessive inheritance, with both parents and three of five unaffected siblings being heterozygous carriers. Together with two previously reported recessive families and the experimentally established neomorphic action of p.(Asp334Asn), the homozygous deletion supports an FBXO31 allelic series comprising dominant gain of function and recessive biallelic loss of function.

BackgroundFebrile neutropenia requires rapid empirical antibiotic therapy, with regimen selection shaped by local prescribing practice and pathogen patterns. We described starting treatment, later drug changes, microbiological findings, and inpatient outcomes. MethodsThis ambispective cohort comprised 96 episodes from 90 patients admitted to a tertiary-level teaching hospital. Treatment and outcome analyses used each episode as the unit of observation. Recorded variables included the starting antibiotics, later regimen modification, microbiology, hospitalization length, invasive fungal infection (IFI) as captured in study records, and disposition. Comparisons based on escalation status were exploratory. ResultCefoperazone-sulbactam appeared in 62/96 initial regimens (64.6%), amikacin in 42 (43.8%), teicoplanin in 28 (29.2%), and meropenem in 14 (14.6%). Eighteen episodes (18.8%) required a change that broadened or substituted antibacterial therapy. Among 31 microbiologically documented infections, 22 (71.0%) yielded Gram-negative organisms and 9 (29.0%) were polymicrobial. Median length of admission was 18.5 days in the escalation group and 9 days in the remainder (p<0.001). Mortality was 27.8% (5/18) with escalation and 5.1% (4/78) without it (p=0.011), with nine inhospital deaths overall (9.4%). ConclusionAntibacterial management differed within this cohort, with treatment escalation required in 18 of 96 episodes. Gram-negative organisms comprised most microbiologically confirmed infections. Escalation marked a clinically complex course with prolonged hospitalization and greater observed mortality; the observational design does not establish comparative efficacy or causation.

Background: The clinical course of acute leukemias and related hematologic neoplasms is defined by aggressive clonal proliferation, severe hematopoietic disruption, and recurrent molecular alterations. Although serial bone marrow biopsies, multiparameter flow cytometry, and next-generation sequencing remain standard surveillance modalities, procedural invasiveness, high costs, and operational turnaround times limit their frequency. Minimally invasive, scalable biomarkers integrating routine hematologic indices, targeted gene expression, circulating oncoprotein levels, and patient compliance metrics may provide an accessible framework for dynamic monitoring. Methods: In this longitudinal cohort study of 66 patients across 272 serial encounters (discrete follow-up intervals: days 0, 14, 41, 71, and 78), we assessed the prognostic value of peripheral complete blood counts (white blood cell count [WBC], hemoglobin [Hb]), molecular indicators (FLT3, NPM1, and DNMT3A transcript levels; targeted soluble FLT3 quantification), and medication adherence. The primary clinical endpoint was longitudinal progression to critical deterioration or disease-related mortality. Generalized linear mixed-effects models (GLMM) with patient-specific random intercepts were constructed to account for intra-subject repeated measures. Predictors were standardized per 1-SD increment. Model performance was assessed via the Akaike Information Criterion (AIC) and the Concordance index (C-index). Results: Leukocyte expansion correlated inversely with hemoglobin concentration (r=-0.877, p<0.001), reflecting bone marrow infiltration and secondary erythroid suppression. Multivariable mixed-effects modeling confirmed that elevated WBC count (adjusted odds ratio [aOR] = 1.52 per 1-SD increase; 95% CI: 1.24-1.86; p<0.001) and reduced medication adherence (aOR = 0.58; 95% CI: 0.44-0.76; p<0.001) independently predicted adverse clinical transition. Integrating targeted molecular markers (FLT3 expression and soluble protein levels) with routine hematologic indices and adherence demonstrated superior calibration and discrimination over single-domain models ({Delta}AIC[&ge;]116; Harrells C-index = 0.81). Conclusions: Readily accessible peripheral hematologic indices, targeted molecular quantification, and medication adherence provide complementary prognostic information regarding disease activity. Integrating these low-burden parameters into clinical workflows offers an efficient, scalable paradigm for early risk stratification in hematologic malignancies.

Background Vitiligo is an acquired depigmenting disorder characterised by melanocyte loss. While immune responses against melanocytes are implicated in its pathogenesis, melanocyte detachment, melanocyte senescence and aberrant epidermal differentiation are increasingly characterised as additional pathological features. Granzyme B (GzmB), classically recognised as an intracellular effector of perforin-dependent cytotoxicity, is increased in vitiligo lesions; however, its extracellular contribution to vitiligo pathology remains unclear. Objectives To determine whether extracellular GzmB contributes to depigmentation and epidermal pathological features relevant to vitiligo, and to define its cellular source and underlying mechanisms. Methods Human vitiligo skin samples, murine depigmentation models and cultured human epidermal cells were analysed. The functional effects of extracellular GzmB were examined by subcutaneous administration of recombinant GzmB in mice. A rhododendrol (RD)-induced leukoderma model was used to evaluate the disease relevance of GzmB and the therapeutic effect of topical GzmB inhibition with VTI-1002. Results GzmB-positive cells were markedly increased in active vitiligo lesions and were predominantly associated with tryptase-positive cells, with limited co-distribution with CD8 or perforin. Vitiligo lesions also showed melanocyte detachment, increased p16INK4A-positive melanocytes and aberrant keratinocyte differentiation. These pathological features were recapitulated in vivo by extracellular GzmB administration, accompanied by focal depigmentation. In cultured melanocytes, GzmB exerted no cytotoxic effects but reduced attachment strength and induced a senescence-associated phenotype characterised by decreased extracellular matrix- and adhesion-related gene expression, increased p16INK4A level, elevated senescence-associated {beta}-galactosidase activity and activation of transforming growth factor-{beta}/SMAD signalling. In keratinocytes, extracellular GzmB promoted aberrant differentiation associated with activation of p53 signalling. Topical inhibition of GzmB in RD-induced leukoderma attenuated depigmentation progression, melanocyte detachment, melanocyte senescence and abnormal epidermal differentiation. Conclusions Extracellular GzmB promotes depigmentation associated with inducing melanocyte detachment, melanocyte senescence and aberrant keratinocyte differentiation. These findings identify extracellular GzmB as a previously underrecognised pathogenic mediator and potential therapeutic target in vitiligo-associated depigmentation.