Search Results (303)

A key function of naturally occurring antibodies is to control pathologically altered cells, such as those with aberrant glycosylation. Age-related diminution in the pool of B cells producing these immunoglobulins is linked to impaired anti-tumor immunity. In this study, the levels of antibodies against tumor-associated carbohydrate antigens (TACAs)—common in gastric cancer (GC) and other malignancies—were analyzed in 235 treatment-naïve GC patients (stages I–IV) and 76 healthy donors using a printed glycan array (PGA). We found that anti-glycan IgM levels, but not IgG, reduced with age in both patients and donors. Crucially, IgM levels against most glycans were significantly lower in the GC cohort compared with healthy donors, a trend that remained after age adjustment. Furthermore, an immunohistochemical analysis revealed that human anti-GalNAcα (Tn) antibodies—a well-characterized TACA in gastrointestinal cancers—bound to tumor cells and exhibited perinuclear and membrane staining in non-tumor surface cells within the same organ. These data support the hypothesis that gastric cancer patients have reduced levels of anti-glycan IgMs, which are responsible for the early recognition of transformed cells. This specific immunodeficiency may contribute to a permissive environment for tumor development. Full article

Background/Objectives: Long-term serological studies are essential to understand how repeated antigenic exposure affects the specific humoral immune response. The aim of this study was to investigate the long-term SARS-CoV-2 antibody dynamics in Austrian blood donors, as representatives of healthy adults, over a period of 36 months after the first SARS-CoV-2 infection. Methods: SARS-CoV-2 anti-N antibody levels were determined in more than 146,000 blood donations collected between 2020 and 2025. In addition, SARS-CoV-2 anti-N and anti-S antibody dynamics were examined in 204 individual blood donors at predefined points in time over a period of 36 months. Reinfections were inferred from increases in anti-N levels within an individual. Vaccination history and self-reported infection data were documented. Results: Anti-N seroprevalence was over 90% from the beginning of 2023 and remained at this level until 2025. Among the longitudinally observed participants, 97% had at least one serologically detected reinfection and 50% had two or more. While anti-N levels continued to increase over time, suggesting cumulative antigenic stimulation, anti-S concentrations and in vitro antibody functionality remained consistently high. Self-reported reinfections underestimated the actual incidence by a factor of six. Symptom profiles shifted toward mild respiratory manifestations, with significantly fewer cases of hyposmia or dysgeusia reported compared to the initial infection. Conclusions: After three years of observation, SARS-CoV-2 immunity is characterized by sustained antibody activity. The results show a transition from persistent, but inherently declining, to a repeatedly rebuilding, enhanced humoral immunity, indicating that SARS-CoV-2 has become endemic in Austria. Full article

Background: Adoptive cell therapy using genetically engineered recombinant T cell receptors (rTCRs) expressed in T cells (TCR-T cell therapy) provides precision targeting of cancer cells expressing tumor-associated or tumor-specific antigens recognized by the rTCRs. Standardized analytical tools are lacking to easily quantify receptor expression. Methods: To overcome this hindrance, a universal tagging system (UniTope & TraCR) was designed consisting of a minimal peptide epitope (UniTope) inserted into the constant region of the rTCR α or β chain and a high-affinity monoclonal antibody (TraCR) specific to this tag. Detailed biophysical, biochemical, and functional assays were performed to evaluate rTCR expression, folding, pairing, and antigen recognition, as well as antibody performance, using the UniTope & TraCR System. Results: Tagged rTCRs were stably expressed in human T cells with surface densities comparable to untagged rTCRs. The TraCR antibody bound UniTope with nanomolar affinity and no detectable cross-reactivity was observed for endogenous proteins expressed by human cells of diverse origin, importantly, including T cells of the natural T cell repertoires of multiple human donors. Functional assays confirmed that UniTope-tagged rTCRs preserved their antigen-specific cytokine secretion and cytolytic activity upon antigen-specific stimulation. The UniTope & TraCR System enabled robust detection of rTCR-expressing T cells by flow cytometry, and rTCR protein expression by Western blot or immunoprecipitation, supporting the quantitative assessment of receptor copy number and structural integrity. Conclusions: The UniTope & TraCR System provides a modular, construct-agnostic platform for monitoring engineered rTCRs, integrated into TCR-T cell therapies currently in development. Full article

Background: Memory B cells (B_mem) facilitate the generation of renewed and rapid antigen-specific antibody responses long after the initial antigen exposure, at a time when circulating serum antibodies may have declined. As the generation and/or recruitment of B_mem is at the core of most vaccination strategies, the assessment of antigen-specific B_mem is highly informative for forecasting and profiling the elicited B cell immune response. Methods: The two prevalent techniques used to detect antigen-specific B_mem cells at single-cell resolution are probe-based flow cytometry and B cell ImmunoSpot, while the measurement of B cell-derived antibodies in culture supernatants of stimulated B cells offers a semi-quantitative alternative. To the best of our knowledge, a direct side-by-side comparison of these assay systems has not yet been reported using the same starting PBMC material in a blinded fashion to test all three assays simultaneously. Results: These three assay systems were run in parallel to detect SARS-CoV-2 Wuhan-1 strain Spike-specific IgG⁺ B_mem in peripheral blood mononuclear cell (PBMC) samples obtained from well-defined cohorts comprising pre-COVID-19 era “naïve” individuals (negative controls), individuals shortly after recovery from a PCR-verified SARS-CoV-2 infection (positive controls), and a cohort of donor PBMCs isolated in 2024 (the experimental group). Each assay was able to discern Spike-exposed individuals from naïve , with ImmunoSpot suggesting superior sensitivity and specificity. ImmunoSpot and flow cytometry results were closely correlated. Conclusions: The study demonstrates that all three assays are suited for the detection of specific B_mem in antigen-primed individuals when such B_mem occur in the mid- to high-frequency range, and that they broadly concur. Strengths and weaknesses of the three test systems are discussed. Full article

Vector-borne parasites might be transmitted through transfusion, notably Plasmodium spp. and Trypanosoma cruzi. Prevention strategies include blood donor screening, deferral, and blood unit treatment by pathogen inactivation methods. At the end of 2015, in line with European guidelines, Italian legislation introduced a questionnaire to identify donors at risk and their screening by serological methods. In early 2016, the Laboratory of Parasitology at Pisa University Hospital started the serological analysis of donors at risk, referring to Transfusion Services located in northwestern Tuscany. The aim of the present study was to describe the prevalence of seropositive donors observed during 8 years of screening. Donors at risk of transmitting malaria were screened by ELISA (Enzyme Linked Immunosorbent Assay). The DRG ELISA kit was employed until 2020, when it was substituted by the Euroimmun ELISA kit based on the results of a comparative evaluation of available commercial kits. Seropositive donors were offered the possibility of Plasmodium DNA testing by Loop-Mediated AMPlification (LAMP) to exclude current infection. Donors at risk of transmitting Chagas disease were screened by ICT employing recombinant antigen until 2021, when it was substituted by ELISA employing lysate antigen because of its higher accuracy. Seropositive donors were further tested by CLIA, and WB was performed in case of discordant results, according to WHO guidelines for diagnosis of chronic Chagas disease. A total of 3754 donors were tested for anti-Plasmodium antibodies, revealing a 6.8% (95% CI = 6.1–7.7%) seroprevalence. Seropositivity was higher among donors from Sub-Saharan Africa (42.9%; 95% CI = 36.1–49.9%) and Southeast Asia (10.6%; 95% CI = 6.7–16.4%). A lower seropositivity was observed when employing Euroimmun ELISA (4.8; 95% CI = 3.8–5.9%) than DRG ELISA (8.2%; 95% CI = 7.1–9.3%). Seropositivity dropped to 3.6% (95% CI = 2.4–5.6) in 2020, likely because of travel restrictions during the COVID-19 pandemic. None of the tested seropositive donors (n = 20) tested positive for Plasmodium DNA LAMP testing. A high proportion of seroreversion was observed after one year of testing. Among 4285 donors tested for anti-T. cruzi antibodies seroprevalence was 0.7% (95% CI = 0.5–1.1%), a higher value than what was observed in a recent national survey. All seropositive donors were born in Europe or Latin America. Seropositivity was apparently lower with ELISA (0.5%, 95% CI = 0.2–1.2%) than ICT (0.8%, 95% CI = 0.6–1.2%), possibly due to ELISA’s higher specificity, although the difference is not significant. No confirmed cases of chronic Chagas disease were identified. The study emphasizes the importance of defining the serological test employed for screening and the need to confirm seropositive results with further testing. The high seroreversion observed in the study suggests repeating seropositive donor screening after a year to minimize deferral and blood unit loss. Full article

Background/Objectives: Epitope-based matching has emerged as a refined approach for assessing donor–recipient compatibility in renal transplantation. However, limited data are available on HLA Class I epitope distribution among Indian patients, particularly from northern India, where substantial allelic diversity is known to influence immunological risk. Methods: This retrospective analysis evaluated HLA Class I single-antigen bead (SAB) antibody data from 218 consecutive renal-transplant candidates who tested positive for anti-HLA antibodies between July 2018 and September 2024. HLA Class I epitopes were identified and analyzed using MATCH IT Antibody Software (Immucor, version 1.5.0). Demographic variables and sensitization history (previous transplant, transfusion, pregnancy) were reviewed. Results: A total of 504 distinct epitopes were identified, with 65GK and 163LG emerging as the most frequent motifs. The predominance of these epitopes mirrors the high prevalence of alleles such as HLA-A*24 and HLA-B*35 reported in North-Indian populations. The data suggest a strong influence of regional allele architecture on the immunogenic epitope landscape. Conclusions: This study provides the first baseline characterization of HLA Class I epitope distribution among northern-Indian renal-transplant candidates. The findings emphasize the need for establishing population-specific HLA epitope databases and highlight the potential of epitope-based matching to enhance donor selection and minimize immunological risk in Indian transplantation programs. Full article

Human T-lymphotropic virus type 1 (HTLV-1) infection is associated with a spectrum of clinical outcomes, ranging from lifelong asymptomatic carriage to severe conditions such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia/lymphoma (ATLL). Although antibody responses are known to shape immune regulation, the functional relevance of IgG idiotype repertoires in HTLV-1 pathogenesis remains poorly understood. This study investigated the immunomodulatory effects of IgG from individuals with distinct HTLV-1 clinical outcomes. IgG was purified from pooled serum samples of asymptomatic carriers (ACs), HAM/TSP, and ATLL patients and used to stimulate peripheral blood mononuclear cells (PBMCs) from healthy donors. Cytokine production in CD4⁺, CD8⁺, and γδ T cells was assessed by flow cytometry. Additionally, proteome-wide IgG reactivity was evaluated using a human protein microarray encompassing over 21,000 proteins, and bioinformatic analyses were conducted to identify protein–protein interaction networks and tissue-specific autoreactivity. HAM/TSP-derived IgG selectively enhanced IFN-γ production in all T-cell subsets and suppressed IL-4 in CD4⁺ T cells. ATLL-derived IgG induced IL-9 and IL-13 production in CD4⁺ T cells, and both HAM/TSP and ATLL IgG elevated IL-13 levels in CD8⁺ T cells. Microarray data revealed distinct autoreactive IgG profiles across clinical groups, targeting immune-related proteins, apoptotic regulators, and proteins expressed in T cells, monocytes, and non-immune tissues such as brain and testis. Notably, no functional or structural clustering was observed in protein–protein interaction networks, suggesting these reactivities reflect complex, idiotype-specific immune alterations rather than compensatory responses. The present findings suggest that HTLV-1 infection may be associated with the development of distinct IgG repertoires that potentially modulate cytokine responses and exhibit broad reactivity toward human proteins. Such patterns could contribute to immune dysregulation and may partially explain the divergent clinical trajectories observed in HAM/TSP and ATLL. Further investigations are warranted to validate these observations at the individual level and to clarify their mechanistic relevance in disease progression. Full article

Background: Brucella canis is a zoonotic pathogen associated with reproductive disorders in dogs and represents an emerging public health concern. Dogs are the only known source of infection for humans, and transmission is often associated with close contact, particularly in occupational settings. Reports of canine and human infections in Europe are increasing, underscoring the need for integrated surveillance to assess the risk of introduction and spread. Objectives: This study aimed to investigate the possible circulation of B. canis in different subgroups of dogs from Central Italy, representing diverse risk contexts (stray, breeding, blood donor, refugee-associated, and previously outbreak-linked dogs), and to generate sentinel data to inform further risk-based surveillance and zoonotic risk assessment. Methods: A comprehensive serological, molecular, and bacteriological survey was conducted on 128 dogs sampled in the Umbria region, covering animals from different backgrounds and risk contexts. Blood samples were tested using bacterial culture, real-time PCR, serum agglutination test, complement fixation test, and/or indirect immunofluorescence antibody test. Results: All tested dogs were negative for B. canis. The upper 95% confidence limit for prevalence was 3.5%, suggesting that widespread circulation is unlikely, although a low/moderate prevalence in specific groups cannot be excluded. Conclusions: Although no cases of B. canis were detected, the results provide sentinel information and highlight the need for continued risk-based surveillance, particularly in low-prevalence areas to prevent introduction of the infection and to enable early detection in case of occurrence. As dogs are the only known source of human infection, veterinary monitoring plays a pivotal role in mitigating zoonotic risks and supporting One Health strategies for evidence-based control. Full article

Background and Objectives: Primary Epstein–Barr virus (EBV) infection in pediatric kidney transplant recipients with donor/recipient mismatch (D+/R−) carries the highest risk of post-transplant lymphoproliferative disorder (PTLD). Current prophylactic strategies are not standardized. Intravenous immunoglobulins (IVIG), containing anti-EBV antibodies, have been proposed as a potential preventive option, but evidence is lacking. This single-center retrospective case–control study evaluated the efficacy of serial IVIG administration in preventing primary EBV infection and promoting long-term immunity in this high-risk population. Materials and Methods: We retrospectively analyzed 26 pediatric kidney transplant recipients (age 1–18 years) with EBV D+/R− mismatch and a median follow-up of 7.5 years. Fourteen patients received scheduled IVIG infusions (200 mg/kg monthly for six months post-transplantation), while twelve received no EBV-directed prophylaxis. The primary endpoint was the cumulative incidence of primary EBV infection, defined as EBV-DNA > 1000 copies/mL in peripheral blood. The secondary endpoint was Epstein–Barr Nuclear Antigen-Immunoglobulin G (EBNA-IgG) seroconversion. Results: Patients receiving IVIG were significantly younger than controls (median age 4.2 vs. 10.8 years, p = 0.01). No significant variations were observed between groups in renal function or immunosuppressive levels during follow-up. IVIG prophylaxis was unexpectedly linked to a higher cumulative incidence of EBV infection compared with controls (64% vs. 25%, p = 0.047). Time-to-event analysis confirmed an increased, although not statistically significant, risk of EBV acquisition in the IVIG group (Hazard Ratio [HR] 3.24, 95% Confidence Interval [CI] 0.87–12.01; p = 0.079). EBV-specific immunity, assessed by EBNA-IgG seroconversion, was comparable between groups (HR 1.78; p = 0.45), confirming no immunological advantage of IVIG. One IVIG-treated patient (7.1%) developed PTLD, while none did in the control group. Conclusions: Scheduled IVIG administration during the first six months after transplantation does not constitute an effective strategy to prevent primary EBV infection or to enhance long-term immunity in high-risk EBV D+/R− pediatric kidney recipients and may even increase susceptibility to viral acquisition. These findings argue against the use of IVIG as EBV prophylaxis in this population. Full article

Background/Objectives: Calcineurin inhibitors (CNI) contribute to renal dysfunction post-transplant. Belatacept is a renal sparing immunosuppressive agent. We sought to determine if the use of belatacept, as an alternative to a CNI-based maintenance immunosuppressive regimen ameliorates the effects of CNI-related nephrotoxicity in lung transplant recipients, while preserving graft function. Methods: Retrospective case series of adult lung transplant recipients (LTR) converted to belatacept with CNI elimination between 2020 and 2023. Primary outcomes were estimated glomerular filtration rate (eGFR) and pulmonary function testing. Secondary outcomes included incidence of rejection, mortality, donor specific antibody (DSA), chronic lung allograft dysfunction, infection, malignancies, and drug discontinuation. Results: Five LTR converted to belatacept with a median follow up of 3.49 years (IQR 16.4). eGFR improved with a median change of +18 mL/min/1.73 m² (IQR 6–34) at 12 months, this was sustained at last-follow-up (+19 mL/min/1.73 m² (IQR 6–34)). Force expiratory volume in 1 s (FEV1) declined from baseline to last follow-up (median change −0.53 L). At a median of 199 days post-conversion (IQR 108–453), belatacept was discontinued in 4/5 (80%) LTR, primarily due to graft dysfunction (3/4), and CNI therapy resumed. No LTR developed CLAD, DSA, malignancy, or died on belatacept. Infection (primarily pulmonary bacterial or fungal) occurred in all LTR on belatacept. Conclusions: Belatacept with complete CNI elimination in LTR resulted in a sustained improvement in renal function in this series but was accompanied by a high discontinuation rate due to worsening graft function. The risks to the graft associated with belatacept and calcineurin inhibitor elimination outweigh any potential renal benefits. Full article

Serological testing for SARS-CoV-2-specific antibodies, particularly those targeting the nucleocapsid protein, plays a key role in assessing past infection and estimating population-level seroprevalence. The seroprevalence of nucleocapsid antibodies against SARS-CoV-2 was evaluated in 1048 blood donors using the Elecsys Anti-SARS-CoV-2 electrochemiluminescence immunoassay. Participants completed a questionnaire to assess risk factors, symptoms during SARS-CoV-2 infection and vaccination status. The overall SARS-CoV-2 seroprevalence was 89.69%. Seroprevalence was not significantly associated with gender or age. In multivariate logistic regression, most investigated risk factors showed no significant association with seroprevalence. However, residence area and vaccination status were independently associated with SARS-CoV-2 seropositivity. Donors from rural areas had significantly higher odds of seropositivity (aOR = 1.68; 95% CI: 1.01–2.79; p = 0.045) compared to those from urban areas. Unvaccinated individuals were more likely to test positive for SARS-CoV-2 compared to vaccinated participants (aOR: 2.59; 95% CI: 1.35–4.99; p = 0.004). After three years of the COVID-19 pandemic, the prevalence of SARS-CoV-2 among blood donors was remarkably high, indicating that the vast majority of this population group had been exposed to the virus. This study highlights the risk factors for SARS-CoV-2 infection and the differences in antibody prevalence between vaccinated and unvaccinated individuals. Our findings underscore the pivotal role of vaccination in controlling the pandemic and provide valuable insights for policymakers in designing targeted strategies to curb future SARS-CoV-2 transmission. Full article

Background: The biosynthesis of Lewis (Le) antigens depends on the FUT3 gene, encoding an α(1,3/4)-fucosyltransferase. Individuals lacking functional FUT3 exhibit a Le(a–b–) phenotype, regardless of secretor status. Methods: This study determined the prevalence of FUT3 single nucleotide variants (SNVs) in Thai blood donors and characterised genotype and allele distributions. We also examined the association between FUT3 variants and the presence of Le antibodies to better understand variability in immune responses. A total of 112 blood donors were recruited, comprising 52 non-responders and 60 responders for Le antibody detection. The FUT3 coding sequence was amplified by polymerase chain reaction and directly sequenced to identify single nucleotide variants (SNVs) and haplotypes. Results: Associations between FUT3 SNVs, haplotypes, and Le antibody responsiveness were subsequently analysed. Thirteen FUT3 SNVs were identified, with c.59T>G (rs28362459) present in all Le(a–b–) cases. The FUT3*01N.17.03 (le^59,1067) haplotype was most common (0.634) and showed the strongest association with Le antibody responsiveness (adjusted OR = 3.052, 95% CI: 1.683–5.534, p < 0.0001). Differences in antibody types, isotypes, and the FUT3*01N.17.03 genotype between groups were not statistically significant. Conclusions: This first study characterises FUT3 variations in Le(a–b–) Thai blood donors and identifies FUT3*01N.17.03 as associated with Le antibody responsiveness, highlighting its relevance for population-specific genetic diagnostics in transfusion medicine. Full article

Recurrence of the original glomerular disease (GN) poses a significant threat to kidney transplant function and longevity. The probability and severity of this recurrence vary, with C3 glomerulopathy and certain forms of FSGS exhibiting particularly high rates. Kidney transplant GN recurrence risk hinges on the characteristics of the initial GN, recipient/donor genetics, recipient age, donor type, end-stage kidney disease (ESRD) progression rate, and proteinuria levels. Standard immunosuppression has limited efficacy in preventing primary disease recurrence; however, agent selection and induction therapy can influence the risk for specific GNs. Diagnosing recurrent GN involves a comprehensive approach, including clinical evaluation, laboratory tests (such as proteinuria, hematuria, and specific biomarkers like anti-PLA2R for membranous nephropathy or complement for C3G), and, critically, an allograft biopsy analyzed with light, immunofluorescence, and electron microscopy. Treatment strategies are evolving towards targeted therapies, such as rituximab for antibody-mediated GN and complement inhibitors for C3G, moving away from broad immunosuppression. This narrative literature review provides practical monitoring algorithms for post-transplant settings, synthesizing information on the incidence, predictors, diagnostic strategies, and therapeutic options for various glomerular disease subtypes. The methodology involved searching MEDLINE, Embase, and Cochrane databases from 1996 to 2025, prioritizing systematic reviews, cohort studies, registries, and interventional reports. Eligibility criteria included adult transplant recipients and English-language reports on recurrent glomerular disease outcomes, excluding most single-patient case reports. Limitations include potential selection bias, omission of relevant studies, and the absence of a formal risk-of-bias assessment or meta-analysis. The evidence base is heterogeneous, with inconsistent outcome reporting and scarce randomized controlled trials. Future efforts should focus on developing predictive biomarkers, standardizing diagnostic and response criteria, conducting multicenter prospective cohorts and pragmatic trials, and creating shared registries with harmonized data. Full article

Xenotransplantation using pig cells, tissues, or organs is advancing toward clinical application to address the shortage of human donor organs for treating organ failure. However, this emerging technology carries the risk of transmitting pathogenic porcine microorganisms, particularly viruses. The recent transmission of a porcine herpesvirus to the first human recipient of a pig heart highlights the urgent need for more rigorous screening of donor pigs. To identify potentially pathogenic porcine viruses, highly sensitive and specific detection methods are required. PCR-based techniques able to detect porcine cytomegalovirus/porcine roseolovirus (PCMV/PRV), hepatitis E virus (HEV), porcine circoviruses (PCV1-4), porcine lymphotropic herpesviruses (PLHV-1-3), porcine endogenous retroviruses (PERVs), porcine parvovirus (PPV), Torque teno sus viruses (TTSuV1,2), atypical porcine pestivirus (APPV) and SARS-CoV-2 were established. Immunological assays that detect antibodies as indirect indicators of infection were established for PCMV/PRV, HEV, PLHVs and PERVs. Since most veterinary laboratories focus on detecting viruses that are pathogenic to pigs and cause economic losses to the swine industry, screening for viruses relevant to xenotransplantation should be conducted in specialized virological diagnostic units. In this context, we present a complete collection of the newest and detailed protocols for comprehensive viral screening, along with guidance on how to implement these methods effectively. Full article

Donor-specific anti-HLA antibodies (DSAs) bind to donor vascular endothelial cells and mediate allograft rejection (AMR), but a clinical challenge for which targeted therapeutic options remain limited. We used a multiplexed single-antigen bead (SAB) assay to detect anti-human leukocyte antigen (HLA) antibodies. Based on the antigens which patient’s antibodies aganist to, we developed bivalent HLA-Fc fusion proteins composed of HLA-derived antigenic domains and human IgG1-Fc effector regions (rA24-Fc and rB13-Fc). Specific binding and functional activity of the HLA-Fc proteins were further validated by flow cytometry, ELISA, complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) assays. Our findings demonstrate that the fusion proteins rA24-Fc and rB13-Fc significantly reduced HLA-specific antibody reactivity in vitro. Notably, rA24-Fc and rB13-Fc selectively bound to B-cell hybridomas (e.g., mouse W6/32 cells) expressing membrane immunoglobulins (BCR) which bound to the most HLA class I antigens. Importantly, rA24-Fc and rB13-Fc elicited antigen-specific, Fc-dependent elimination of the specific B-cell hybridomas. This study highlights HLA-Fc fusion proteins as a promising therapeutic strategy for the antigen-specific suppression of depletion of alloreactive B cells through dual cytotoxic mechanisms. This precision targeted to BCR of B cells approach is used to apply to the treatment of antibody-mediated rejection. Full article