Changes in epigenetic profiles throughout early childhood and their relationship to the response to pneumococcal vaccination.

BACKGROUND: Pneumococcal infections are a major cause of morbidity and mortality in young children and immaturity of the immune system partly underlies poor vaccine responses seen in the young. Emerging evidence suggests a key role for epigenetics in the maturation and regulation of the immune system in health and disease. The study aimed to investigate epigenetic changes in early life and to understand the relationship between the epigenome and antigen-specific antibody responses to pneumococcal vaccination. METHODS: The epigenetic profiles from 24 healthy children were analyzed at 12 months prior to a booster dose of the 13-valent pneumococcal conjugate vaccine (PCV-13), and at 24 months of age, using the Illumina Methylation 450 K assay and assessed for differences over time and between high and low vaccine responders. RESULTS: Our analysis revealed 721 significantly differentially methylated positions between 12 and 24 months (FDR < 0.01), with significant enrichment in pathways involved in the regulation of cell-cell adhesion and T cell activation. Comparing high and low vaccine responders, we identified differentially methylated CpG sites (P value < 0.01) associated with HLA-DPB1 and IL6. CONCLUSION: These data imply that epigenetic changes that occur during early childhood may be associated with antigen-specific antibody responses to pneumococcal vaccines.

Specificity of human natural antibodies referred to as anti-Tn.

To understand the role of human natural IgM known as antibodies against the carbohydrate epitope Tn, the antibodies were isolated using GalNAcα-Sepharose affinity chromatography, and their specificity was profiled using microarrays (a glycan array printed with oligosaccharides and bacterial polysaccharides, as well as a glycopeptide array), flow cytometry, and inhibition ELISA. The antibodies bound a restricted number of GalNAcα-terminated oligosaccharides better than the parent monosaccharide, e.g., 6-O-Su-GalNAcα and GalNAcα1-3Galß1-3(4)GlcNAcß. The binding with several bacterial polysaccharides that have no structural resemblance to the affinity ligand GalNAcα was quite unexpected. Given that GalNAcα is considered the key fragment of the Tn antigen, it is surprising that these antibodies bind weakly GalNAcα-OSer and do not bind a wide variety of GalNAcα-OSer/Thr-containing mucin glycopeptides. At the same time, we have observed specific binding to cells having Tn-positive glycoproteins containing similar glycopeptide motifs in a conformationally rigid macromolecule. Thus, specific recognition of the Tn antigen apparently requires that the naturally occurring "anti-Tn" IgM recognize a complex epitope comprising the GalNAcα as an essential component and a fairly long amino acid sequence where the amino acids adjacent to GalNAcα do not contact the antibody paratope; i.e., the antibodies recognize a spatial epitope or a molecular pattern rather than a classical continuous sequence. In addition, we have not found any increase in the binding of natural antibodies when GalNAcα residues were clustered. These results may help in further development of anticancer vaccines based on synthetic Tn constructs.

Ras isoforms selectively regulate antigen-specific immune response.

H-/K-Ras and N-Ras isoforms were proposed to lack functional specificities due to similarity in 1-165 amino acids. As recent studies implied Ras isoform-specific developmental effects, we examined their functional specificity using Leishmania major infection, anti-hapten antibody response and carrier-specific T cell response. While N-Ras overexpression increased L. major infection in resistant C57BL/6 mice, H-Ras or K-Ras overexpression reduced the infection in susceptible BALB/c mice. These Ras isoforms differentially regulated anti-TNP antibody response in TNP-Ova-primed, but not in TNP-Ficoll- or TNP-LPS-primed, BALB/c mice. Ras isoform-specific silencing selectively modulated Ova-specific T cell response. The data indicate Ras isoform-specific regulation of antigen-specific immune response.

Clinical Application Evaluation of a Fourth-Generation HIV Antigen Antibody Combination Screening Assay.

BACKGROUND: Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) are infectious diseases with high mortality. Early diagnosis is crucial. Combining HIV antibody and p24 antigen, the Elecsys HIV combi PT assay is a fourth generation HIV screening assay. The sensitivity and specificity of this assay was examined. METHODS: A total of 111,556 samples was conducted from January 1, 2016, to June 30, 2018 in Zhongshan Hospital of Yat-Sen University. We conducted a fourth-generation HIV test of retrospective HIV screening samples and assessed the reliability of using signal-to-cutoff (S/CO) ratios to distinguish false positive HIV antibody reactions and analyzed false positives. RESULTS: A total of 122 specimens were confirmed as HIV-1 infected by western blot (WB) and HIV nucleic acid assays. The median S/CO ratio for HIV false positive specimens was 3.27, while for the HIV-infected specimen it was 391.7. Receiver operating characteristic (ROC) analysis showed that the best diagnostic point for HIV was 22.85 S/CO. The sensitivity, specificity, and Youden index were 100%, 97.8%, and 0.978, respectively. The highest false positive rate of 26.4% was found in patients with malignant tumors and blood diseases. CONCLUSIONS: The results of this study show that the fourth-generation Elecsys HIV combination PT test can identify early HIV infected and can be a useful adjunct to help clinicians to manage the disease by viral load testing and starting an appropriate therapy. Our research data provides a reference for subsequent research and HIV testing in the region.

Fast and Efficient Fc-Specific Photoaffinity Labeling To Produce Antibody-DNA Conjugates.

Antibody-DNA conjugates are powerful tools for DNA-assisted protein analysis. Growing usage of these methods demands efficient production of high-quality conjugates. We developed an easy and fast synthesis route yielding covalent antibody-DNA conjugates with a defined conjugation site and low batch-to-batch variability. We utilize the Z domain from protein A, containing the unnatural amino acid 4-benzoylphenylalanine (BPA) for photoaffinity labeling of the antibodies' Fc region. Z(xBPA) domains are C-terminally modified with triple-glycine (G3)-modified DNA-oligonucleotides via enzymatic Sortase A coupling. We show reliable modification of the most commonly used IgG's. To prove our conjugates' functionality, we detected antibody-antigen binding events in an assay called Droplet Barcode Sequencing for Protein analysis (DBS-Pro). It confirms not only retained functionality for both conjugate parts but also the potential of using DBS-Pro for quantifying protein abundances. As intermediates are easily storable and our approach is modular, it offers a convenient strategy for screening various antibody-DNA conjugates using the same starting material.

An unusual cysteine VL87 affects the antibody fragment conformations without interfering with the disulfide bond formation.

The Cys residues are almost perfectly conserved in all antibodies. They contribute significantly to the antibody fragment stability. The relevance of two natural contiguous Cys residues of an anti-recombinant human-follicle stimulation hormone (rhFSH) in a format of single-chain variable fragment (scFv) was studied. This scFv contains 5 Cys residues: VH22 and VH92 in the variable heavy chain (VH) and VL23, VL87 and VL88 in the variable light chain (VL). The influence of two unusual contiguous Cys at positions VL87 and VL88 was studied by considering the wild type fragment and mutant variants: VL-C88S, VL-C87S, VL-C87Y. The analysis was carried out using antigen-binding ability measurement by indirect specific ELISA and a detailed molecular modeling that comprises homology methods, long molecular dynamics simulations and docking. We found that VL-C87 affected the antibody fragment stability without interfering with the disulfide bond formation. The effect of mutating the VL-C87 by a usual residue at this position like Tyr caused distant structural changes at the VH region that confers a higher mobility to the VH-CDR2 and VH-CDR3 loops improving the scFv binding to the antigen.

Stability Characterization of a Vaccine Antigen Based on the Respiratory Syncytial Virus Fusion Glycoprotein.

Infection with Respiratory Syncytial Virus (RSV) causes both upper and lower respiratory tract disease in humans, leading to significant morbidity and mortality in both young children and older adults. Currently, there is no licensed vaccine available, and therapeutic options are limited. During the infection process, the type I viral fusion (F) glycoprotein on the surface of the RSV particle rearranges from a metastable prefusion conformation to a highly stable postfusion form. In people naturally infected with RSV, most potent neutralizing antibodies are directed to the prefusion form of the F protein. Therefore, an engineered RSV F protein stabilized in the prefusion conformation (DS-Cav1) is an attractive vaccine candidate. Long-term stability at 4°C or higher is a desirable attribute for a commercial subunit vaccine antigen. To assess the stability of DS-Cav1, we developed assays using D25, an antibody which recognizes the prefusion F-specific antigenic site Ø, and a novel antibody 4D7, which was found to bind antigenic site I on the postfusion form of RSV F. Biophysical analysis indicated that, upon long-term storage at 4°C, DS-Cav1 undergoes a conformational change, adopting alternate structures that concomitantly lose the site Ø epitope and gain the ability to bind 4D7.

The role of monogamous bivalency and Fc interactions in the binding of anti-DNA antibodies to DNA antigen.

Antibodies to DNA (anti-DNA) are the serological hallmark of systemic lupus erythematosus. These antibodies can bind DNA avidly by monogamous bivalency, a mechanism which requires the interaction of both Fab combining regions with antigenic determinants on the same polynucleotide. To explore further this mechanism, we tested Fab and F(ab')2 fragments prepared from IgG from patient plasmas in an ELISA with native DNA antigen, detecting antibody with a peroxidase conjugated anti-Fab reagent. These studies showed that Fab fragments, which can only bind monovalently, had negligible activity. Although bivalent F(ab')2 fragments would be predicted to bind DNA, these fragments also showed poor anti-DNA activity. Control studies showed that the fragments retained antibody activity to tetanus toxoid and an EBV antigen preparation. Together, these findings suggest that anti-DNA avidity depends on monogamous bivalency, with the antibody Fc portion also influencing DNA binding, in a mechanism which can be termed Fc-dependent monogamous bivalency.

[BIOLOGICAL AND IMMUNOCHEMICAL PROPERTIES OF POLYREACTIVE IMMUNOGLOBULINS].

A previously unknown phenomenon of acquired polyreactivity for serum immunoglobulins, which were subjected either to solutions of KSCN (3.0-5.0 M), low/high pH (pH 2.2-3.0), or heating to 58-60 degrees C, was described by us in 1990 year. Much later, eleven years after that, similar data were published by others, which completely confirmed our results concerning the influence of either chaotropic ions or the drastic shift of pH on immunoglobulins polyreactive properties. Our further investigations of polyreactive serum immunoglobulins (PRIG) properties have shown that the mechanism of non-specific interaction between PRIG and antigens much differs from the mechanism of interaction between specific antibodies and corresponding antigens. Later we have shown that the increasing of PRIG reactivity could be induced in vivo, and PRIG are one of serum components for human or animal sera. Then, it could be suggested that PRIG can perform certain biological functions. Studying of PRIG's effect on the phagocytosis of microbes by peritoneal cells or the tumor growth have shown that PRIG can play a certain role in protecting the body from infections and probably can influence on the development of various pathological processes. Recently we have also found that PRIG IgG contents significantly increases in aged people. These data demonstrate that further investigations of PRIG's immunochemical properties and studying of their biological role in organism protection from various diseases is very intriguing and important.

An integrative structure-based framework for predicting biological effects mediated by antipeptide antibodies.

A general framework is presented for predicting quantitative biological effects mediated by antipeptide antibodies, primarily on the basis of antigen structure (possibly featuring intrinsic disorder) analyzed to estimate epitope-paratope binding affinities, which in turn is considered within the context of dose-response relationships as regards antibody concentration. This is illustrated mainly using an approach based on protein structural energetics, whereby expected amounts of solvent-accessible surface area buried upon epitope-paratope binding are related to the corresponding binding affinity, which is estimated from putative B-cell epitope structure with implicit treatment of paratope structure, for antipeptide antibodies either reacting with peptides or cross-reacting with cognate protein antigens. Key methods described are implemented in SAPPHIRE/SUITE (Structural-energetic Analysis Program for Predicting Humoral Immune Response Epitopes/SAPPHIRE User Interface Tool Ensemble; publicly accessible via http://freeshell.de/~badong/suite.htm). Representative results thus obtained are compared with published experimental data on binding affinities and quantitative biological effects, with special attention to loss of paratope sidechain conformational entropy (neglected in previous analyses) and in light of key in-vivo constraints on antigen-antibody binding affinity and antibody-mediated effects. Implications for further refinement of B-cell epitope prediction methods are discussed as regards envisioned biomedical applications including the development of prophylactic and therapeutic antibodies, peptide-based vaccines and immunodiagnostics.

Predominant structural configuration of natural antibody repertoires enables potent antibody responses against protein antigens.

Humoral immunity against diverse pathogens is rapidly elicited from natural antibody repertoires of limited complexity. But the organizing principles underlying the antibody repertoires that facilitate this immunity are not well-understood. We used HER2 as a model immunogen and reverse-engineered murine antibody response through constructing an artificial antibody library encoded with rudimentary sequence and structural characteristics learned from high throughput sequencing of antibody variable domains. Antibodies selected in vitro from the phage-displayed synthetic antibody library bound to the model immunogen with high affinity and specificities, which reproduced the specificities of natural antibody responses. We conclude that natural antibody structural repertoires are shaped to allow functional antibodies to be encoded efficiently, within the complexity limit of an individual antibody repertoire, to bind to diverse protein antigens with high specificity and affinity. Phage-displayed synthetic antibody libraries, in conjunction with high-throughput sequencing, can thus be designed to replicate natural antibody responses and to generate novel antibodies against diverse antigens.

The network of antigen-antibody reactions in adult women with breast cancer or benign breast pathology or without breast pathology.

The Immunoglobulin G (IgG) antibody response to different protein antigens of the mammary ductal carcinoma by adult women affected by Breast Cancer (BC) distinguishes at least 103 proteins that differ in their molecular weights (MW). The IgG producing cell clones (nodes) coexist with each other in each individual organism and share energy resources among themselves, as well as factors that control the level of expression and Specificity of their IgG antibodies. So, it can be proposed that among them there is a Network of interconnections (links) unveiled by the antigens, which specifically react with the IgG antibodies produced by the clones. This Network possibly regulates IgG antibodies' activity and effectiveness. We describe the Network of nodes and links that exists between the different antigens and their respective IgG producing cell clones against the extracted protein antigens from the cells of the T47D Cell-Line, in 50 women with BC, 50 women with Benign Breast Pathology (BBP) and 50 women without breast pathology (H). We have found that women with BBP have the highest number of Links, followed by the H group and, lastly, the women with BC, a finding which suggests that cancer interferes with the Connectivity between the IgG producing cell clones and blocks the expression of 322 links in women with BBP and 32 links in women with H. It is also plausible that the largest number of links in the women with BBP indicates the Network's state of arousal that provides protection against BC. On the other hand, there were many missing links in the BC group of women; the clone which lost more links in the BC group was the hub 24, which point to some of the antigens of T47D as potentially useful as vaccines, as the immune system of women with BBP is well aware of them.

Measuring affinity constants of 1450 monoclonal antibodies to peptide targets with a microarray-based label-free assay platform.

Monoclonal antibodies (mAbs) are major reagents for research and clinical diagnosis. For their inherently high specificities to intended antigen targets and thus low toxicity in general, they are pursued as one of the major classes of new drugs. Yet binding properties of most monoclonal antibodies are not well characterized in terms of affinity constants and how they vary with presentations and/or conformational isomers of antigens, buffer compositions, and temperature. We here report a microarray-based label-free assay platform for high-throughput measurements of monoclonal antibody affinity constants to antigens immobilized on solid surfaces. Using this platform we measured affinity constants of over 1410 rabbit monoclonal antibodies and 46 mouse monoclonal antibodies to peptide targets that are immobilized through a terminal cysteine residue to a glass surface. The experimentally measured affinity constants vary from 10 pM to 200 pM with the median value at 66 pM. We compare the results obtained from the microarray-based platform with those from a benchmarking surface-plasmon-resonance-based (SPR) sensor (Biacore 3000).

Toxocaríase experimental em hamster / Experimental toxocariasis in hamsters

INTRODUÇÃO: Toxocaríase é uma infecção parasitária de distribuição global, causada pela fase larval de Toxocara spp. Os hospedeiros naturais são cães e gatos, nos quais o parasita completa o ciclo chegando a fase adulta. Outros hospedeiros podem ser infectados pela fase larval do parasita, após ingestão de ovos embrionados do solo, mãos contaminadas, fomites, ou ingestão de carne ou vísceras de animais infectados. Em hospedeiros paratênicos o parasita não completa o ciclo, invadindo em estágio larval vísceras ou outros tecidos, onde podem sobreviver e induzir a patologia. O presente estudo teve como objetivo caracterizar o hamster (Mesocricetus auratus), como modelo experimental de toxocaríase, inicialmente através do estudo das lesões histopatológicas em fígado, pulmão e rim. A caracterização da resposta imunológica do modelo, foi feita através do estudo de citocinas envolvidas nas respostas Th1 e Th2, e foi sugerida uma correlação entre alterações glomerulares e depósitos de complexos antígenos-anticorpo pré-formados na circulação. MÉTODOS: Hamsters foram inoculados com ovos embrionados de Toxocara canis, e mantidos no biotério do Instituto de Medicina Tropical de São Paulo. O estudo histopatológico foi desenvolvido utilizando-se cortes parafinados corados por hematoxilina e eosina. Para detecção de antígenos nos tecidos foram realizadas reações imunohistoquímicas, utilizando-se anticorpo monoclonal e policlonal anti- Toxocara canis. Utilizando-se o soro dos animais infectados e animais controle, foi realizada pesquisa de antígeno e anticorpo por ELISA. Para pesquisa de imunoglobulinas IgG e IgM e complemento, foram utilizados cortes congelados de rins para realização de reação de Imunofluorescência. Fragmentos de rins foram incluídos para utilização em microscopia eletrônica, para detecção de antígenos de toxocara e de imune complexos. Para caracterização de resposta imunológica foram estudadas citocinas envolvidas na resposta Th1 e Th2 por técnica de...

INTRODUCTION: Toxocariasis is a parasitic infection of global distribution, caused by the larval stage of Toxocara spp. The natural hosts are dogs and cats, in which the parasite completes the cycle reaching adulthood. Other hosts can be infected with the larval stage of the parasite, after ingestion of embryonated eggs from the soil, contaminated hands, fomites, or ingestion of meat or viscera of infected animals. In paratenics hosts the parasite not complete the cycle, encroaching on larval stage in viscera or other tissues where they can survive and induce pathology. The present study aimed to characterize the hamster, Mesocricetus auratus, as experimental model of toxocariasis, initially through the study of histopathological lesions in the liver, lung and kidney. The characterization of immune response model, was made through the study of cytokines Th1 and Th2 responses involved, and a correlation was suggested between glomerular changes and antibody-antigen complexes deposits preformed in the circulation. METHODS: Hamsters were inoculated with embryonated eggs of Toxocara canis, and kept in the bioterium of the Institute of Tropical Medicine of the São Paulo. The histopathologic study was developed using paraffin slides stained by hematoxylin and eosin. For detection of antigens in tissues immunohistochemistry reactions were performed using monoclonal and polyclonal anti-Toxocara canis sera. Using the serum of infected and control animals, search has been carried out of antigen and antibody by ELISA. For the search of immunoglobulins IgG, IgM and complement, were used slides prepared from frozen fragments of kidneys and a immunofluorescence reaction. Fragments of kidneys were included for electron microscopy to detect antigens of Toxocara and immune complexes. For characterization of Th1 and Th2 response cytokines involved were detected by RT-PCR technique. RESULTS: Histopathological findings demonstrated since the beginning of the...

Anti-phospholipase A2 receptor antibodies and the pathogenesis of membranous nephropathy.

Since the early 2000s, considerable advances have been achieved in the understanding of molecular pathomechanisms of human membranous nephropathy (MN), inspired by studies of Heymann nephritis, a faithful experimental model. These studies led to the identification of neutral endopeptidase, the type-M phospholipase A2 receptor (PLA2R), and cationic bovine serum albumin as target antigens of circulating and deposited antibodies in neonatal alloimmune, adult 'idiopathic', and early childhood MN, respectively. A genome-wide association study further showed a highly significant association of the PLA2R1 and the HLA-DQA1 loci with idiopathic MN in patients of white ancestry. The time has come to revisit the spectrum of MN based on the newly identified antigen-antibody systems which should be considered as molecular signatures of the disease, challenging the uniform histological definition. Although some uncertainties remain as to the pathogenic effects of anti-PLA2R antibodies because of the lack of an appropriate experimental model, the value of these antibodies as biomarkers for diagnosis and disease activity is increasingly being recognized. It is not exaggerated to state that they have induced a paradigm shift in the monitoring of patients with MN, thus opening a new era of personalized medicine.

Cryptic polyreactivity of IgG expressed by splenic marginal zone B-cell lymphoma.

Polyreactive antibodies represent a significant fraction of immune repertoires and play an important role in the immune defense and immune homeostasis. Polyreactive B-cell receptors (BCR), however, are frequently expressed by B-cell lymphomas. It was suggested that polyreactive BCR on lymphoma cells might deliver stimulation signals by binding to various endogenous or exogenous antigens, thus promoting the survival of the malignant cells. In addition to natural polyreactive antibodies, immune repertoires contain antibodies that acquire polyreactivity after exposure to different redox-active substances such as reactive oxygen species, iron ions and heme. Here, we demonstrate that an antibody cloned from a patient's splenic marginal zone B-cell lymphoma acquires physiologically relevant binding affinity to various autoantigens following exposure to heme. We elucidated the mechanisms underlying polyreactive antigen binding. The results obtained in this study imply that antigen-binding receptors expressed on some malignant cells acquire polyreactivity after exposure to redox substances that are released at sites of inflammation or as a result of cellular damage. The acquisition of novel BCR specificities under hemolytic or inflammatory conditions may play an important role in the physiopathology of certain B-cell malignancies.

Targeting and depletion of circulating leukocytes and cancer cells by lipophilic antibody-modified erythrocytes.

There is a great interest in targeting and selective ablation of populations of circulating cells for research or therapeutic purposes. Red blood cells (RBCs) are readily available and fully biocompatible long-circulating intravascular carriers (natural life is 120days) that are amenable to chemical modifications, drug loading and reinjection. Here we demonstrate that using our previously described lipophilic ligand painting strategy, red blood cells (RBCs) could be in one step converted into targeted entities that selectively seek and bind various cells in vitro and in vivo. In vitro, RBCs modified with lipophilic anti-EpCAM or anti-CD45 antibodies efficiently bound to cancer cells and leukocytes, forming characteristic rosettes. In vivo, intravenously injected RBCs painted with anti-CD45 antibody immediately associated with CD45 positive cells in blood, forming RBC-leukocyte rosettes. Moreover, anti-CD45-modified RBCs, but not the same amount of anti-CD45 antibody or anti-CD45-lipid conjugate (1-2µg/mouse), depleted over 50% of CD45+ leukocytes from circulation, with main clearance organs of leukocytes being liver and spleen with no visible deposition in kidneys and lungs. Anti-CD20 (Rituximab)-painted RBCs efficiently (over 90%) depleted CD19+/CD20+/CD45+ human lymphoma cells in mantle cell lymphoma (MCL) JeKo-1 model, while the same amount of rituximab-lipid (2µg/mouse) was much less efficient in lymphoma cell depletion. Treatment of MCL mice with rituximab-modified RBCs carrying only 2µg of the antibody resulted in a significant prolongation of survival as compared to the same amount of antibody-lipid control. Lipophilic ligand-painted RBCs is a novel tool that can be utilized for targeting blood borne cells for experimental immunology and drug delivery applications.

Reconciling the structural attributes of avian antibodies.

Antibodies are high value therapeutic, diagnostic, biotechnological, and research tools. Combinatorial approaches to antibody discovery have facilitated access to unique antibodies by surpassing the diversity limitations of the natural repertoire, exploitation of immune repertoires from multiple species, and tailoring selections to isolate antibodies with desirable biophysical attributes. The V-gene repertoire of the chicken does not utilize highly diverse sequence and structures, which is in stark contrast to the mechanism employed by humans, mice, and primates. Recent exploitation of the avian immune system has generated high quality, high affinity antibodies to a wide range of antigens for a number of therapeutic, diagnostic and biotechnological applications. Furthermore, extensive examination of the amino acid characteristics of the chicken repertoire has provided significant insight into mechanisms employed by the avian immune system. A paucity of avian antibody crystal structures has limited our understanding of the structural consequences of these uniquely chicken features. This paper presents the crystal structure of two chicken single chain fragment variable (scFv) antibodies generated from large libraries by phage display against important human antigen targets, which capture two unique CDRL1 canonical classes in the presence and absence of a non-canonical disulfide constrained CDRH3. These structures cast light on the unique structural features of chicken antibodies and contribute further to our collective understanding of the unique mechanisms of diversity and biochemical attributes that render the chicken repertoire of particular value for antibody generation.

Antibody recognition of fluorinated haptens and antigens.

Regarding its many roles for lead optimization and drug development, fluorine will definitely continue to be of major importance in medicinal chemistry. With safe and selective fluorinating agents at hands, the use of fluorinated compounds has become routine in pharmaceutical and material sciences and many of the well-appreciated organofluorine inductive effects are now understood. In contrast, our knowledge of how fluorine affects binding affinity and selectivity of proteins and antibodies at the molecular level is by far less advanced. Thus, applications of fluorinated haptens and antigens in the mapping of binding epitopes for various antibodies of diagnostic and therapeutic relevance, as well as for the generation of immune modulating agents and ligands with enhanced T cell affinity are reviewed. Moreover, recent examples of vaccines against cocaine and cancer based on selectively fluorinated antigens with improved antigenic properties are presented.