Antibodies

21 pages, 1316 KiB

Open AccessReview

Teprotumumab for Thyroid Eye Disease: Mechanism, Clinical Efficacy, and Current Challenges

by Yuan Zong, Shuang Qiu, Mingming Yang, Jing Zhang, Yaru Zou, Yuxin Jing, Kyoko Ohno-Matsui and Koju Kamoi

Antibodies 2025, 14(3), 55; https://doi.org/10.3390/antib14030055 - 30 Jun 2025

Abstract

Thyroid eye disease (TED) is a complex autoimmune disorder characterized by orbital inflammation and tissue remodeling. Teprotumumab, a fully human monoclonal antibody targeting insulin-like growth factor-1 receptor (IGF-1R), represents a significant breakthrough in TED treatment. This review comprehensively analyzes the therapeutic role of [...] Read more.

Thyroid eye disease (TED) is a complex autoimmune disorder characterized by orbital inflammation and tissue remodeling. Teprotumumab, a fully human monoclonal antibody targeting insulin-like growth factor-1 receptor (IGF-1R), represents a significant breakthrough in TED treatment. This review comprehensively analyzes the therapeutic role of teprotumumab in TED management. Mechanistically, teprotumumab inhibits the IGF-1R/TSHR signaling complex, thereby reducing orbital fibroblast differentiation and inflammatory responses. Phase II and III clinical trials have demonstrated its remarkable efficacy in reducing proptosis and improving clinical activity scores, with the benefits extending to both active and chronic TED cases. Real-world studies have validated these findings further and expanded its potential applications to various clinical scenarios, including dysthyroid optic neuropathy and steroid-resistant cases. However, several challenges remain. These include treatment-related adverse effects such as hyperglycemia and hearing impairment, with emerging evidence suggesting ethnic variations in susceptibility. The high cost of treatment poses significant accessibility barriers, while limited long-term follow-up data and potential disease recurrence necessitate further investigation. This review synthesizes the current evidence to inform clinical decision-making and highlights areas requiring additional research to optimize teprotumumab’s therapeutic application in TED management. Full article

(This article belongs to the Section Antibody-Based Therapeutics)

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21 pages, 885 KiB

Open AccessArticle

Survival Outcomes and Prognostic Factors in Rheumatoid Arthritis Patients Receiving Biologic or Targeted Synthetic Therapy: Real-World Data

by Zhaklin Apostolova, Tanya Shivacheva and Tsvetoslav Georgiev

Antibodies 2025, 14(3), 54; https://doi.org/10.3390/antib14030054 - 30 Jun 2025

Abstract

Objectives: The present study aimed to evaluate the long-term survival of patients with rheumatoid arthritis (RA) receiving biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) in a real-world setting, and to identify key prognostic factors influencing mortality within this cohort. Methods: This retrospective, [...] Read more.

Objectives: The present study aimed to evaluate the long-term survival of patients with rheumatoid arthritis (RA) receiving biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) in a real-world setting, and to identify key prognostic factors influencing mortality within this cohort. Methods: This retrospective, observational cohort study analyzed 165 patients with confirmed RA who were on b/tsDMARD treatment for at least six months as of June 2017. Patient data, including demographics, disease duration, prior therapeutic regimens, and global functional status were extracted from medical records to collect data covering a seven-year follow-up period, extending from June 2017 to December 2024. Corticosteroid use was defined as continuous systemic intake during the RA activity analysis period. Survival outcomes were analyzed using Kaplan-Meier methods and multivariate Cox proportional hazards models to identify independent predictors of mortality. Results: Over a mean follow-up of 9.4 years, the mortality rate was 13.5 deaths per 1000 treatment-years, with an overall survival rate of 87.3%. Advanced functional disability and prolonged corticosteroid use were independently associated with higher mortality risk. In subgroup analyses, chronic kidney disease significantly increased mortality among patients on TNF inhibitors. In contrast, patients who remained on their initial anti-IL6 therapy had lower mortality, though this may reflect survivor bias. Conclusions: This study highlights the importance of long-term b/tsDMARD intervention in RA patients, with observed low mortality and high survival rates. Subgroup findings suggest the importance of comorbidity management in TNFi users and therapeutic stability in anti-IL6 users. Full article

(This article belongs to the Section Antibody-Based Therapeutics)

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14 pages, 1544 KiB

Open AccessBrief Report

Impact of Light-Chain Variants on the Expression of Therapeutic Monoclonal Antibodies in HEK293 and CHO Cells

by Alexander Veber, Dennis Lenau, Polyniki Gkragkopoulou, David Kornblüh Bauer, Ingo Focken, Wulf Dirk Leuschner, Christian Beil, Sandra Weil, Ercole Rao and Thomas Langer

Antibodies 2025, 14(3), 53; https://doi.org/10.3390/antib14030053 - 24 Jun 2025

Abstract

Recombinantly produced monoclonal antibodies (mabs) belong to the fastest growing class of biotherapeutics. In humans, antibodies are classified into five different classes: IgA, IgD, IgE, IgG and IgM. Most of the therapeutic mabs used in the clinic belong to the IgG class, albeit [...] Read more.

Recombinantly produced monoclonal antibodies (mabs) belong to the fastest growing class of biotherapeutics. In humans, antibodies are classified into five different classes: IgA, IgD, IgE, IgG and IgM. Most of the therapeutic mabs used in the clinic belong to the IgG class, albeit other antibody classes, e.g., IgM, have been evaluated in clinical stages. Antibodies are composed of heavy chains paired with a light chain. In IgM and IgA, an additional chain, the J-chain, is present. Two types of light chains exist in humans: the κ-light chain and the λ-light chain. The κ-light chain predominates in humans and is used in the vast majority of therapeutic IgG. The reason for the preference of the κ-light chain in humans is not known. Our study investigates whether light-chain selection influences the productivity of the clinically validated mabs adalimumab and trastuzumab. Both mabs were expressed as IgG and IgM with a κ- or a λ-light chain in HEK293 cells. Besides comparing the expression levels of the different mabs, we also evaluated whether the passage number of the cell line has an impact on product yield. In addition, the expressions of adalimumab, trastuzumab, an anti-CD38 and an anti-PD-L1-antibody were analyzed in HEK293 and CHO cells when both the κ- and λ-light chains are present. In summary, IgG outperformed IgM variants in expression efficacy, while light-chain selection had minimal impact on the overall expression levels. The yields of all mab variants were higher in fresh cells, despite cell cultures with a high cell passage number having higher cell densities and cell numbers at the time of harvest. The incorporation of a particular light chain occurred at similar rates in HEK293 and CHO cells. Full article

(This article belongs to the Section Antibody Discovery and Engineering)

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53 pages, 1486 KiB

Open AccessReview

Fragment-Based Immune Cell Engager Antibodies in Treatment of Cancer, Infectious and Autoimmune Diseases: Lessons and Insights from Clinical and Translational Studies

by Ge Yang and Mohammad Massumi

Antibodies 2025, 14(3), 52; https://doi.org/10.3390/antib14030052 - 24 Jun 2025

Abstract

Since the advent of recombinant DNA technologies and leading up to the clinical approval of T cell engager blinatumomab, the modular design of therapeutic antibodies has enabled the fusion of antibody fragments with proteins of various functionalities. This has resulted in an expansive [...] Read more.

Since the advent of recombinant DNA technologies and leading up to the clinical approval of T cell engager blinatumomab, the modular design of therapeutic antibodies has enabled the fusion of antibody fragments with proteins of various functionalities. This has resulted in an expansive array of possible mechanisms of action and has given birth to fragment-based antibodies (fbAbs) with immune cell engager modalities. In searchable databases, the preclinical development of these antibodies has shown promise; however, clinical outcomes and restructuring efforts involving these agents have produced mixed results and uncertainties. Amid budgetary cuts in both academia and industry, critical planning and evaluation of drug R&D would be more essential than ever before. While many reviews have provided outstanding summaries of preclinical phase fbAbs and cataloged relevant clinical trials, to date, very few of the articles in searchable databases have comprehensively reviewed the details of clinical outcomes along with the underlying reasons or potential explanations for the success and failures of these fbAb drug products. To fill the gap, in this review, we seek to provide the readers with clinically driven insights, accompanied by translational and mechanistic studies, on the current landscape of fragment-based immune cell engager antibodies in treating cancer, infectious, and autoimmune diseases. Full article

(This article belongs to the Special Issue A Festschrift Celebrating Dr. Dimiter Stanchev Dimitrov: Antibodies, Innovation, and Impact on Infectious Disease and Cancer Research)

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11 pages, 218 KiB

Open AccessReview

Circulating Antibodies Against DSG1 and DSG3 in Patients with Oral Lichen Planus: A Scoping Review

by Domenico De Falco, Francesca Iaquinta, Doriana Pedone, Alberta Lucchese, Dario Di Stasio and Massimo Petruzzi

Antibodies 2025, 14(2), 51; https://doi.org/10.3390/antib14020051 - 18 Jun 2025

Abstract

Oral Lichen Planus (OLP) is a chronic autoimmune disease with potential overlap with Pemphigus Vulgaris (PV), particularly in erosive forms. Desmoglein 1 and 3 are transmembrane glycoproteins of desmosomes, typically involved in PV. This scoping review aims to evaluate the presence and potential [...] Read more.

Oral Lichen Planus (OLP) is a chronic autoimmune disease with potential overlap with Pemphigus Vulgaris (PV), particularly in erosive forms. Desmoglein 1 and 3 are transmembrane glycoproteins of desmosomes, typically involved in PV. This scoping review aims to evaluate the presence and potential pathogenetic role of anti-desmoglein 1 (Dsg1) and anti-desmoglein 3 (Dsg3) antibodies in OLP. A literature search was conducted on MEDLINE/PubMed, Ovid, and Scopus up to April 2025. Human studies reporting OLP patients with anti-Dsg1 and/or anti-Dsg3 antibodies were included. Data from 11 studies were analyzed by diagnosis, age/sex, oral site involvement, immunofluorescence, and ELISA testing. Erosive OLP was most frequently associated with anti-Dsg1/Dsg3 positivity, mainly in women aged 40–60. Immunofluorescence was positive in some cases, while the ELISA test almost consistently detected anti-Dsg1 and Dsg3 antibodies. However, in many instances, antibody titers did not reach the threshold value, despite the presence being detectable. This finding suggests that anti-Dsg1/Dsg3 antibodies may represent epiphenomena of chronic inflammation in erosive OLP, indicating an immune-serological overlap with PV but lacking direct pathogenicity. Furthermore, the role of Dsg3 in oral squamous cell carcinoma, by promoting enzymes that degrade the extracellular matrix and enhance tumor invasiveness, highlights the complex functions of desmogleins beyond autoimmunity. Full article

(This article belongs to the Special Issue Antibody and Autoantibody Specificities in Autoimmunity)

12 pages, 1047 KiB

Open AccessBrief Report

Light Chain Isotype and Antibody-Specificity Impact on Virus Neutralization

by Lin Sun, Roman Palt, Georg Schütz, Esther Föderl-Höbenreich, Laura Brod, Antonia Hermle, Anja Lux, Herta Steinkellner and Somanath Kallolimath

Antibodies 2025, 14(2), 50; https://doi.org/10.3390/antib14020050 - 17 Jun 2025

Abstract

Therapeutic antibodies with lambda light chains (λ-Abs) are underrepresented compared to kappa light chains (κ-Abs). Here, we evaluated two SARS-CoV-2-specific monoclonal antibodies (mAbs) that exhibit high (P5C3) and low (H4) antigen binding as κ and λ variants. mAbs expressed in glycoengineered Nicotiana benthamiana [...] Read more.

Therapeutic antibodies with lambda light chains (λ-Abs) are underrepresented compared to kappa light chains (κ-Abs). Here, we evaluated two SARS-CoV-2-specific monoclonal antibodies (mAbs) that exhibit high (P5C3) and low (H4) antigen binding as κ and λ variants. mAbs expressed in glycoengineered Nicotiana benthamiana did not show differences in expression levels, glycosylation, and antigen binding, while κ-Abs exhibited slightly increased thermodynamic stability over λ-Abs. SARS-CoV-2 neutralization and IgG-FcγR immune complex studies revealed increased activities of H4 IgG1κ compared to H4 IgG1λ, with no differences observed between P5C3 variants. Our results indicate that constant light chain variability and Ab specificity contribute to Ab features, a fact that should be considered in engineering therapeutics. Full article

(This article belongs to the Section Antibody Discovery and Engineering)

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13 pages, 653 KiB

Open AccessReview

Regulatory T Cell in Kidney Transplant: The Future of Cell Therapy?

by Ahmad Matarneh, Meet Patel, Kinna Parikh, Amanda Karasinski, Gurwant Kaur, Vaqar Shah, Nasrollah Ghahramani and Naman Trivedi

Antibodies 2025, 14(2), 49; https://doi.org/10.3390/antib14020049 - 17 Jun 2025

Abstract

The long-term use of immunosuppressive drugs following kidney transplantation increases the risk of life-threatening infections, malignancies, and, paradoxically, eventual allograft rejection. Therefore, achieving a balance between over-immunosuppression and under-immunosuppression is critical to optimizing patient outcomes. One promising approach is immune cell-based therapy using [...] Read more.

The long-term use of immunosuppressive drugs following kidney transplantation increases the risk of life-threatening infections, malignancies, and, paradoxically, eventual allograft rejection. Therefore, achieving a balance between over-immunosuppression and under-immunosuppression is critical to optimizing patient outcomes. One promising approach is immune cell-based therapy using suppressor immune cells to modulate the immune response more precisely. Among these, regulatory T cells (Tregs) are the most extensively studied and have shown significant potential in the post-transplant setting. Tregs are broadly categorized into thymus-derived and peripherally derived subsets. Physiologically, they play key roles in maintaining immune tolerance, including in autoimmune diseases and within the tumor microenvironment. Their immunosuppressive functions are mediated through both contact-dependent and contact-independent mechanisms. Studies investigating the use of Tregs following kidney transplantation have shown encouraging results. This review summarizes the biology of Tregs and highlights current evidence supporting their role in transplant immunotherapy. Full article

(This article belongs to the Special Issue Antibody-Mediated Rejection in Kidney Transplantation)

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18 pages, 1733 KiB

Open AccessArticle

Humanized VHH-hFc Fusion Proteins Targeting the L-HN Fragment of Tetanus Toxin Provided Protection In Vivo

by Yating Li, Kexuan Cheng, Jiazheng Guo, Yujia Jiang, Qinglin Kang, Rong Wang, Peng Du, Chen Gao, Yunzhou Yu, Zhixin Yang, Wei Wang and Jiansheng Lu

Antibodies 2025, 14(2), 48; https://doi.org/10.3390/antib14020048 - 13 Jun 2025

Abstract

Background: Tetanus toxin, produced by Clostridium tetani, is the second deadliest known toxin. Antibodies capable of neutralizing tetanus toxin (TeNT) are vital for preventing and treating tetanus disease. Methods: Herein, we screened thirty-six single variable domains on a heavy chain (VHHs) binding [...] Read more.

Background: Tetanus toxin, produced by Clostridium tetani, is the second deadliest known toxin. Antibodies capable of neutralizing tetanus toxin (TeNT) are vital for preventing and treating tetanus disease. Methods: Herein, we screened thirty-six single variable domains on a heavy chain (VHHs) binding to the light chain (L) and the translocation domain (HN) (L-HN) fragment of TeNT from a phage-display library. Then, the L-HN-specific clones were identified, humanized, and fused with a human fragment crystallizable region (hFc) to form humanized VHH-hFc fusion proteins. Results: The humanized VHH-hFc fusion proteins TL-16-h1-hFc, TL-25-h1-hFc, and TL-34-h1-hFc possessed potent efficacy with high binding affinity, specificity, and neutralizing activity. Only 0.3125 μg was required for TL-16-h1-hFc or TL-25-h1-hFc, and 0.625 μg was required for TL-34-h1-hFc to provide full protection against 10 × Lethal Dose 50 (LD₅₀) TeNT. In the prophylactic setting, 125 μg/kg of TL-16-h1-hFc or TL-25-h1-hFc provided full protection even when they were injected 12 days before exposure to 10 × LD₅₀ TeNT, while TL-34-h1-hFc was less effective. In the therapeutic setting, 25 μg/kg of TL-16-h1-hFc or TL-25-h1-hFc could provide complete protection when administered 24 h after exposure to 5 × LD₅₀ TeNT, while TL-34-h1-hFc required 50 μg/kg. Conclusion: Our results suggest that TL-16-h1-hFc, TL-25-h1-hFc, and TL-34-h1-hFc provide a bright future for the development of anti-TeNT preventive or therapeutic drugs. Full article

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10 pages, 345 KiB

Open AccessReview

Adoptive Cell Immunotherapy in Relapse/Refractory Epstein–Barr Virus-Driven Post-Transplant Lymphoproliferative Disorders

by Martina Canichella and Paolo de Fabritiis

Antibodies 2025, 14(2), 47; https://doi.org/10.3390/antib14020047 - 12 Jun 2025

Abstract

Post-transplant lymphoproliferative disorders (PTLD) represent a life-threatening complication following solid organ transplantation (SOT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT), particularly in patients with relapsed or refractory (R/R) disease, where therapeutic options are limited and prognosis is poor. Among emerging strategies, adoptive cellular [...] Read more.

Post-transplant lymphoproliferative disorders (PTLD) represent a life-threatening complication following solid organ transplantation (SOT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT), particularly in patients with relapsed or refractory (R/R) disease, where therapeutic options are limited and prognosis is poor. Among emerging strategies, adoptive cellular immunotherapy—specifically Epstein–Barr virus-specific cytotoxic T lymphocytes (EBV-CTLs)—significantly improved outcomes in this challenging patient population. EBV-CTLs restore virus-specific immunity and induce sustained remissions with minimal toxicity, even in heavily pretreated individuals. The most promising cellular product to date is tabelecleucel, an off-the-shelf, allogeneic EBV-specific T-cell therapy, which is currently the only cellular therapy approved by the European Medicines Agency (EMA) for the treatment of R/R EBV-positive PTLD following SOT or allo-HSCT. This review aims to provide an overview of PTLD treatment with a specific focus on adoptive cellular immunotherapy. We highlight the most robust clinical outcomes reported with EBV-CTLs, particularly those achieved with tabelecleucel, and explore emerging cellular approaches such as CAR T-cell therapy, which may further broaden therapeutic strategies in the near future. Full article

(This article belongs to the Section Antibody-Based Therapeutics)

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19 pages, 2671 KiB

Open AccessArticle

Three-Dimensional Modeling of Camelus dromedarius T Cell Receptor Gamma (TRG)_Delta (TRD)/CD1D Complex Reveals Different Binding Interactions Depending on the TRD CDR3 Length

by Salvatrice Ciccarese, Marie-Paule Lefranc, Giulia C. M. Perrone, Pietro D’Addabbo and Ciro Leonardo Pierri

Antibodies 2025, 14(2), 46; https://doi.org/10.3390/antib14020046 - 29 May 2025

Abstract

Background: In the adaptive immune response of the dromedary (Camelus dromedarius, Camdro), the T cell receptor (TR) repertoire of the gamma–delta (γδ) T cells is unusually diversified both by somatic hypermutation in rearranged TR gamma (TRG) and delta (TRD) genes and [...] Read more.

Background: In the adaptive immune response of the dromedary (Camelus dromedarius, Camdro), the T cell receptor (TR) repertoire of the gamma–delta (γδ) T cells is unusually diversified both by somatic hypermutation in rearranged TR gamma (TRG) and delta (TRD) genes and by the diversity in sequence and length of the third complementarity-determining region (CDR3) of the TRD chain. Methods: The purpose was to investigate, in the absence of 3D structures, the role of Camdro γδ T cells, focusing on the binding interactions at the interface between the V-gamma and V-delta domains, and in complex with the CD1D, a major histocompatibily class I (MH1)-like glycoprotein presenting lipid antigen in association with B2M. A combination of hypermutated TRG dromedary cDNA clones was paired with TRD clones bearing very long, long, or short CDR3s, all isolated from the spleen of a single animal. Results: The 3D models of the Camdro TRG_TRD/CD1D_B2M complexes were inferred using the Homo sapiens 3D structure and the ImMunoGeneTics (IMGT) numbering for V, C, and G domains, and investigated for binding interactions at the interface of the paired V-gamma_V-delta and at the interface with CD1D. Our results suggest that transcripts with long CDR3s may derive from a population of CD1D-restricted γδ T cells. Both the CD1D G-alpha1-like and G-alpha-2 like domain helices were contacted by both the V-gamma and V-delta CDR-IMGT loops. Conclusions: Our findings further emphasize the similarity between the γδ T cells population we analyzed in Camelus dromedarius and the CD1D-restricted γδ NKT cells in Homo sapiens. Full article

(This article belongs to the Special Issue Recombinant Binding Proteins and Genetically Engineered T-cells Targeting Intracellular Neoantigens)

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18 pages, 8713 KiB

Open AccessArticle

Protective Potential and Functional Role of Antibodies Against SARS-CoV-2 Nucleocapsid Protein

by Alexandra Rak, Ekaterina Bazhenova, Polina Prokopenko, Victoria Matyushenko, Yana Orshanskaya, Konstantin V. Sivak, Arina Kostromitina, Larisa Rudenko and Irina Isakova-Sivak

Antibodies 2025, 14(2), 45; https://doi.org/10.3390/antib14020045 - 28 May 2025

Abstract

Cases of new COVID-19 infection, which manifested in 2019 and caused a global socioeconomic crisis, still continue to be registered worldwide. The high mutational activity of SARS-CoV-2 leads to the emergence of new antigenic variants of the virus, which significantly reduces the effectiveness [...] Read more.

Cases of new COVID-19 infection, which manifested in 2019 and caused a global socioeconomic crisis, still continue to be registered worldwide. The high mutational activity of SARS-CoV-2 leads to the emergence of new antigenic variants of the virus, which significantly reduces the effectiveness of COVID-19 vaccines, as well as the sensitivity of diagnostic test systems based on variable viral antigens. These problems may be solved by focusing on highly conserved coronavirus antigens, for example nucleocapsid (N) protein, which is actively expressed by coronavirus-infected cells and serves as a target for the production of virus-specific antibodies and T cell responses. It is known that anti-N antibodies are non-neutralizing, but their protective potential and functional activity are not sufficiently studied. Here, the protective effect of anti-N antibodies was studied in Syrian hamsters passively immunized with polyclonal sera raised to N(B.1) recombinant protein. The animals were infected with 10⁵ or 10⁴ TCID₅₀ of SARS-CoV-2 (B.1, Wuhan or BA.2.86.1.1.18, Omicron) 6 h after serum passive transfer, and protection was assessed by weight loss, clinical manifestation of disease, viral titers in the respiratory tract, as well as by the histopathological evaluation of lung tissues. The functional activity of anti-N(B.1) antibodies was evaluated by complement-dependent cytotoxicity (CDC) and antibody-dependent cytotoxicity (ADCC) assays. The protection of anti-N antibodies was evident only against a lower dose of SARS-CoV-2 (B.1) challenge, whereas almost no protection was revealed against BA.2.86.1.1.18 variant. Anti-N(B.1) monoclonal antibodies were able to stimulate both CDC and ADCC. Thus, anti-N(B.1) antibodies possess protective activity against homologous challenge infection, which is possibly mediated by innate Fc-mediated immune reactions. These data may be informative for the development of N-based broadly protective COVID-19 vaccines. Full article

(This article belongs to the Section Humoral Immunity)

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20 pages, 399 KiB

Open AccessReview

IgM Antibody Detection as a Diagnostic Marker for Acute Toxoplasmosis: Current Status of Studies and Main Limitations

by Karolina Sołowińska and Lucyna Holec-Gąsior

Antibodies 2025, 14(2), 44; https://doi.org/10.3390/antib14020044 - 21 May 2025

Abstract

Accurate dating of Toxoplasma gondii infection is essential for effective clinical management, particularly in pregnant women and immunocompromised individuals, where distinguishing acute from chronic infection informs treatment decisions. Serological detection of IgM antibodies is a key tool in diagnosing recent toxoplasmosis; however, its [...] Read more.

Accurate dating of Toxoplasma gondii infection is essential for effective clinical management, particularly in pregnant women and immunocompromised individuals, where distinguishing acute from chronic infection informs treatment decisions. Serological detection of IgM antibodies is a key tool in diagnosing recent toxoplasmosis; however, its reliability is compromised by persistent IgM responses, cross-reactivity, and assay variability. While IgM lacks sufficient specificity to serve as a standalone marker of acute infection, it remains an important component of serological panels. This review summarizes current IgM detection methods and explores advancements aimed at improving diagnostic accuracy with a focus on recombinant antigens, which have emerged as promising alternatives to traditional Toxoplasma lysate antigen-based immunoassays. This paper also explores alternative methods of differentiating chronic and acute toxoplasmosis and outlines key areas for future research. Full article

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15 pages, 2551 KiB

Open AccessArticle

IgG to Galactose-Alpha-1,3-Galactose: Impact of Alpha-Gal IgE Sensitization, Blood Type, and Tick Bites

by Samuel M. Ailsworth, Matthew MacCallum, Nathan E. Richards, Lisa J. Workman, Pamela Schoppee Bortz, Thomas Makin, Thomas A. E. Platts-Mills and Jeffrey M. Wilson

Antibodies 2025, 14(2), 43; https://doi.org/10.3390/antib14020043 - 16 May 2025

Abstract

Background: Antibodies to galactose-alpha-1,3-galactose (alpha-gal), particularly the IgM and IgG isotypes, are abundant in human sera. These antibodies are known to be an important xenotransplantation barrier, but the full implications of these antibodies to health and disease remain incompletely understood. By contrast, IgE [...] Read more.

Background: Antibodies to galactose-alpha-1,3-galactose (alpha-gal), particularly the IgM and IgG isotypes, are abundant in human sera. These antibodies are known to be an important xenotransplantation barrier, but the full implications of these antibodies to health and disease remain incompletely understood. By contrast, IgE to alpha-gal is uncommon in the population but has been associated with tick bites and causally linked with mammalian meat allergy, often now known as alpha-gal syndrome (AGS). To date, there have been few population-based studies that have investigated alpha-gal IgG levels in relation to demographic factors, diet, tick bites, and mammalian meat allergy. Methods: Adults, predominantly healthcare workers, were recruited for a COVID-19 vaccine study. At least one serum sample was collected, and subjects completed questionnaires to provide demographic, diet, and tick exposure data. Alpha-gal IgG, IgE, and total IgG were measured using the ImmunoCAP platform, and blood group was assessed via reverse typing using stored serum. We also assessed alpha-gal IgG levels among subjects with AGS, recruited from an allergy clinic. Results: The median age of the 267 subjects in the vaccine cohort was 42 years, and median alpha-gal IgG levels were 3.0 μg/mL. Alpha-gal IgG levels were higher among the 43 (16.1%) subjects who had alpha-gal IgE sensitization (≥0.1 IU/mL) and among subjects lacking the B blood group antigen (blood groups A and O). Alpha-gal IgG levels did not differ between the subjects who had asymptomatic alpha-gal IgE sensitization and those who had meat allergy. However, both groups had higher alpha-gal IgG levels than subjects who lacked alpha-gal IgE sensitization. Subjects who reported prior tick or chigger bites had higher alpha-gal IgG levels than those without a bite history, regardless of alpha-gal IgE sensitization status. Conclusions: In a population-based cohort, alpha-gal IgG antibodies were found to be prevalent, and levels were increased in subjects with blood groups A and O, subjects who were alpha-gal IgE sensitized, and those who reported a history of tick bites. Full article

(This article belongs to the Section Humoral Immunity)

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16 pages, 1990 KiB

Open AccessArticle

Neutralization of the Pandemic Influenza A/H1N1 Virus with Lama glama Humanized Nanobodies (VHH)

by Zeila Yazmín Páez-Hernández, Jose Luis Stephano-Hornedo, Jose Alberto Bolaños-Prats, Iván Córdova-Guerrero, Mariana Macías-Alonso, Joaquín G. Marrero, Angel Pulido Capiz and Victor García González

Antibodies 2025, 14(2), 42; https://doi.org/10.3390/antib14020042 - 16 May 2025

Abstract

Background/Objetives: Nanobodies (VHH) have become an excellent tool for diagnosis, therapy, and research since VHH shows a high capability of recognizing and neutralizing antigens. VHHs are highly soluble and stable at high temperatures, and in the presence of chaotropic agents, they offer significant [...] Read more.

Background/Objetives: Nanobodies (VHH) have become an excellent tool for diagnosis, therapy, and research since VHH shows a high capability of recognizing and neutralizing antigens. VHHs are highly soluble and stable at high temperatures, and in the presence of chaotropic agents, they offer significant advantages over other biological therapeutic agents. This study aimed to identify and humanize VHH fragments with neutralizing potential against the influenza A/H1N1 virus. Methods: A library of VHH antibody fragments was produced by phage display technique against an inactivated influenza A/H1N1 vaccine. Three VHH sequences were selected and humanized. Specifically, the recognition capacity of the antibodies denominated 2-C10 and 2-C10H was confirmed by ELISA and western blot (WB), as well as their microneutralization capacity in a cellular model, suggesting their potential therapeutic use in patients infected with the influenza A/H1N1 virus. Molecular docking assays were used to support the mechanism of viral inhibition. Results: The VHHs 2-C10 and 2-C10H showed specific recognition of influenza A/H1N1 antigens by ELISA and Western Blot and demonstrated neutralizing activity in vitro. The optimal VHH, 2-C10H, showed 75% neutralization capacity at a concentration of 1.56 μg/mL against the A/H1N1 viral strain, potentially through the inactivation of hemagglutinin protein, a phenomenon supported by molecular docking assays. Conclusions: This study presents a strategic approach to identify VHH candidates that may be useful for diagnosing and potentially treating patients already infected by the A/H1N1 virus, as it may reduce the severity of their symptoms. Full article

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13 pages, 1960 KiB

Open AccessArticle

Generative Deep Learning Design of Single-Domain Antibodies Against Venezuelan Equine Encephalitis Virus

by Jinny L. Liu, Gabrielle C. Bayacal, Jerome Anthony E. Alvarez, Lisa C. Shriver-Lake, Ellen R. Goldman and Scott N. Dean

Antibodies 2025, 14(2), 41; https://doi.org/10.3390/antib14020041 - 14 May 2025

Abstract

Background/Objectives: Venezuelan equine encephalitis virus (VEEV) represents a significant biothreat with no FDA-approved vaccine currently available, highlighting the need for alternative therapeutic strategies. Single-domain antibodies (sdAbs) present a potential alternative to conventional antibodies, due to their small size and ability to recognize cryptic [...] Read more.

Background/Objectives: Venezuelan equine encephalitis virus (VEEV) represents a significant biothreat with no FDA-approved vaccine currently available, highlighting the need for alternative therapeutic strategies. Single-domain antibodies (sdAbs) present a potential alternative to conventional antibodies, due to their small size and ability to recognize cryptic epitopes. Methods: This research describes the development and preliminary evaluation of VEEV-binding sdAbs generated using a generative artificial intelligence (AI) platform. Using a dataset of known alphavirus-binding sdAbs, the AI model produced sequences with predicted affinity for the E2 glycoprotein of VEEV. These candidate sdAbs were expressed in a bacterial periplasmic system and purified for initial assessment. Results: Enzyme-linked immunosorbent assays (ELISAs) indicated binding activity of the sdAbs to VEEV antigens. In vitro neutralization tests suggested inhibition of VEEV infection in cultured cells for some of the candidates. Conclusions: This study demonstrates how generative AI can expedite antiviral therapeutic development and establishes a framework for quick responses to emerging viral threats when extensive example databases are unavailable. Additional refinement and validation of AI-generated sdAbs could establish effective VEEV therapeutics. Full article

(This article belongs to the Section Antibody Discovery and Engineering)

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14 pages, 2399 KiB

Open AccessArticle

Purification of Human Immunoglobulin G with Bathophenanthroline–Zn²⁺, –Fe²⁺, or –Cu²⁺ Complexes

by Thisara Jayawickrama Withanage, Ron Alcalay, Olga Krichevsky, Ellen Wachtel, Ohad Mazor and Guy Patchornik

Antibodies 2025, 14(2), 40; https://doi.org/10.3390/antib14020040 - 12 May 2025

Abstract

Background/Objectives: Pharmaceutical companies are aware of the ongoing effort to satisfy the increasing global demand for therapeutic-grade monoclonal antibodies (mAbs), an especially difficult challenge for poor and developing countries. We present a simple, economical, single-step purification approach at neutral pH for polyclonal human [...] Read more.

Background/Objectives: Pharmaceutical companies are aware of the ongoing effort to satisfy the increasing global demand for therapeutic-grade monoclonal antibodies (mAbs), an especially difficult challenge for poor and developing countries. We present a simple, economical, single-step purification approach at neutral pH for polyclonal human IgG (hIgG), which does not require any expensive ligands, chromatography columns, polymers, or membranes. Methods/Results: Instead, porous precipitates of commercial, recyclable aromatic [bathophenanthroline:cation] complexes were found to efficiently capture impurity proteins from CHO cells or E. coli lysate while maintaining the majority of the highly concentrated hIgG (5–15 mg/mL) in the supernatant. [(Batho)₃:Zn²⁺] complexes were the most promising, resulting in hIgG with a purity of ≈95%, by SDS-PAGE. This purified hIgG is monomeric (by dynamic light scattering, DLS) and preserves the native secondary structure (by far UV circular dichroism spectroscopy, CD). The process yield is >90% (by densitometry) and is maintained after a 100-fold increase in the reaction volume, which required only proportional increases in reagents. Conclusions: Although Protein A chromatographic columns, the industry gold standard, have a limited binding capacity, are costly, and require familiarity with column maintenance, we are attempting, by our efforts, to help to produce a more efficient, simple, and economical purification platform. Full article

(This article belongs to the Section Antibody-Based Therapeutics)

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18 pages, 4678 KiB

Open AccessArticle

Validation and Optimization of PURE Ribosome Display for Screening Synthetic Nanobody Libraries

by Bingying Liu and Daiwen Yang

Antibodies 2025, 14(2), 39; https://doi.org/10.3390/antib14020039 - 2 May 2025

Abstract

Background/Objectives: PURE (Protein synthesis Using Recombinant Elements), an ideal system for ribosome display, has been successfully used for nanobody selection. However, its limitations in nanobody selection, especially for synthetic nanobody libraries, have not been clearly elucidated, thereby restricting its utilization. Methods: The PURE [...] Read more.

Background/Objectives: PURE (Protein synthesis Using Recombinant Elements), an ideal system for ribosome display, has been successfully used for nanobody selection. However, its limitations in nanobody selection, especially for synthetic nanobody libraries, have not been clearly elucidated, thereby restricting its utilization. Methods: The PURE ribosome display selection process was closely monitored using RNA agarose gel electrophoresis to assess the presence of mRNA molecules in each fraction, including the flow-through, washing, and elution fractions. Additionally, a real-time validation method for monitoring each biopanning round was implemented, ensuring the successful enrichment of target protein-specific binders. The selection process was further optimized by introducing a target protein elution step prior to the EDTA-mediated disassembly, as well as by altering the immobilization surfaces. Finally, the efficiency of PURE ribosome display was enhanced by replacing the spacer gene. Results: The efficiency of PURE ribosome display was merely 4% with an unfavourable spacer gene. Using this spacer gene, EGFP- and human fatty acid-binding protein 4-specific nanobodies from a synthetic nanobody library were we successfully identified through optimizing the selection process. Choosing a spacer gene less prone to secondary structure formation increased significantly its efficiency in displaying synthetic nanobody libraries. Conclusions: Implementing a target protein elution step prior to EDTA-mediated disassembly and modifying the immobilization surfaces effectively increase selection efficiency. For PURE ribosome display, efficiency was further improved using a suitable spacer gene, enabling the display of large libraries. Full article

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24 pages, 4948 KiB

Open AccessArticle

A Targeted Integration-Based CHO Cell Platform for Simultaneous Antibody Display and Secretion

by Jessica P. Z. Ng, Mariati Mariati, Jiawu Bi, Matthew Wook Chang and Yuansheng Yang

Antibodies 2025, 14(2), 38; https://doi.org/10.3390/antib14020038 - 28 Apr 2025

Abstract

Objective: We developed a targeted integration-based CHO cell platform for simultaneous antibody display and secretion, enabling a streamlined transition from antibody library screening to production without requiring the re-cloning of antibody genes. Methods: The platform consists of a CHO master cell line with [...] Read more.

Objective: We developed a targeted integration-based CHO cell platform for simultaneous antibody display and secretion, enabling a streamlined transition from antibody library screening to production without requiring the re-cloning of antibody genes. Methods: The platform consists of a CHO master cell line with a single-copy landing pad, a helper vector expressing FLPe recombinase, and bi-functional targeting vectors. Recombinase-mediated cassette exchange was utilized to integrate targeting vectors into the landing pad. Bi-functional vectors were designed by incorporating a minimal furin cleavage sequence (mFCS), RRKR, and various 2A peptides between the heavy chain (HC) and a membrane anchor. Results: Incomplete cleavage at the mFCS and 2A sites facilitated the expression of both membrane-bound and secreted antibodies, while mutations in the 2A peptide produced a range of display-to-secretion ratios. However, a fraction of secreted antibodies retained 2A residues attached to the HC polypeptides. Further analysis demonstrated that modifying the first five amino acids of the 2A peptide significantly influenced furin cleavage efficiency, resulting in different display-to-secretion ratios for targeting vectors containing mFCS-2A variant combinations. To overcome this, we designed nine-amino-acid FCS variants that, when placed between the HC and membrane anchor, provided a range of display-to-secretion ratios and eliminated the issue of attached 2A residues in the secreted antibodies. Vectors with lower display levels proved more effective at distinguishing cells expressing high-affinity antibodies with closely matched binding affinities. The platform also demonstrated high sensitivity in isolating high-affinity antibody-expressing cells and supported robust antibody production. Conclusion: This targeted integration-based CHO platform enables efficient, in-format screening and production of antibodies with tunable display-to-secretion profiles. It provides a powerful and scalable tool for accelerating the development of functional, manufacturable therapeutic antibodies. Full article

(This article belongs to the Special Issue Emerging Antibody Engineering Strategies and Applications for Immunotherapy of Cancer)

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19 pages, 1878 KiB

Open AccessReview

The Role of Monoclonal Antibodies as Therapeutics in HPV-Related Head and Neck Cancers: An Updated Review

by Michael Zalin, Shaan Patel, Carter Coggins and Vikrant Rai

Antibodies 2025, 14(2), 37; https://doi.org/10.3390/antib14020037 - 24 Apr 2025

Abstract

Background/Objectives: The increasing prevalence of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) has necessitated a revaluation of therapeutic strategies. HPV-driven OPSCC differs from HPV-negative OPSCC due to its distinct molecular signatures, increased radiosensitivity, and better prognoses. However, despite these differences, treatment strategies [...] Read more.

Background/Objectives: The increasing prevalence of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) has necessitated a revaluation of therapeutic strategies. HPV-driven OPSCC differs from HPV-negative OPSCC due to its distinct molecular signatures, increased radiosensitivity, and better prognoses. However, despite these differences, treatment strategies have remained largely uniform, resulting in minimal reductions in morbidity and exposing HPV-positive patients to unnecessary toxicity. Monoclonal antibodies (mAbs) have become a promising therapeutic option due to their ability to target treatment with fewer systemic side effects. Immune checkpoint inhibitors (ICIs) such as pembrolizumab have shown efficacy in enhancing the immune response against tumors, while EGFR inhibitors like cetuximab offer an alternative modality. Current clinical trials aim to refine dosing regimens and identify combination strategies that may enhance therapeutic outcomes. Results: Despite promising evidence, several challenges hinder the widespread adoption of mAbs as a standard treatment for HPV-positive OPSCC in clinical practice. This review examines the current role of mAbs in HPV-positive OPSCC treatment, highlighting their limitations and future research directions. Conclusions: Further studies are needed to optimize patient selection, establish standardized treatment protocols, and investigate the long-term benefits of mAb-based therapies in this patient population. Full article

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