Protamine-reactive natural IgM antibodies in human sera. Characterization of the epitope demonstrates specificity of antigenic recognition; occurrence indicates obscurity of origin and function.

We have identified a set of natural IgM antibodies in human serum that are reactive with protamines, a class of low molecular weight basic nucleoproteins that are synthesized de novo in the postpubertal testis and are unique to sperm. Those antibodies were detected by ELISA in significant titer in all of 100 sera of normal adult males and females and in 26 of 28 sera of normal pediatrics aged 7 d to 2 yr. Commonality between the protamine-reactive IgM antibodies of pediatric and adult sera was established by the demonstration of similarity in antigen recognition and reaction kinetics. Therefore, the role of protamines as either immunogenic stimulus or antigenic target of that set of natural antibodies is not likely. The antigenic site recognized by the protein-reactive serum IgM antibodies was characterized by comparison with the pattern of antigen recognition by a monoclonal antibody to human sperm protamines (HPmAb). By the use of synthetic peptides simulating the amino acid sequences of various segments of human protamine 2 and of polyarginine, polylysine, and histones as test antigens, the principle characteristic of the antigenic site recognized by both HPmAb and the serum IgM antibodies was inferred to be that of clustered arginyl residues with an apparent minimum requirement of four arginyl residues, including a triplet, within a six residue piece; for both, the reaction was shown to be not dependent upon charge attraction. A series of immunoabsorption procedures indicated that the protamine-reactive serum IgM antibodies are a discrete set with a high order of specificity. A search of protein data bases revealed that the putative minimum epitope is present in four or five human autogenous proteins, all moieties of the immune system, and in a number of viral proteins. The possible implications of those findings are discussed in the light of early hypotheses concerning the origin and function of natural antibodies and the many recent reports of identification of natural antibodies in normal human sera. The set of natural antibodies identified in this study may be unique or may represent a class of antibodies present in the repertoire that, by virtue of the obscurity of their origin or function, have not been previously or extensively recognized.

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Naturally occurring immunoglobulin M antibodies: enhancement of phagocytic and microbicidal activities of human neutrophils againstToxoplasma gondii

Parasitology ◽

10.1017/s003118200006368x ◽

1992 ◽

Vol 104 (3) ◽

pp. 427-432 ◽

Cited By ~ 22

Author(s):

E. Konishi ◽

M. Nakao

Keyword(s):

Early Stage ◽

Immunoglobulin M ◽

Human Neutrophils ◽

Microscopical Examination ◽

Igm Antibodies ◽

Igm Antibody ◽

Naturally Occurring ◽

Human Sera ◽

Antibody Levels ◽

Natural Igm

Naturally occurring immunoglobulin M antibodies toToxoplasma gondiiin human sera were examined for their ability to enhance toxoplasmacidal activities of human neutrophils to show a role of natural antibodies in immunity to the early stage ofToxoplasmainfection in humans. Neutrophils were mixed with tachyzoites at a ratio of 1:5 in the presence or absence of antibodies and were cultured for 1–18 h for microscopical examination. The count of tachyzoites phagocytosed in 200 neutrophils within 1 h was significantly higher in the presence of sera with natural IgM antibody levels of > 0.8 than those of < 0.1, with 2.4- to 2.9-fold differences (P< 0.02). The total tachyzoite counts at 18 h decreased to 26–39% of those at 1 h in the presence of natural IgM antibody levels of > 0.8 (P< 0.01), while the counts at 1 h consistently increased by 18 h in the absence of natural IgM antibodies. These results indicate that relatively high levels of natural IgM antibodies enhanced phagocytic and microbicidal activities of neutrophils againstToxoplasma. The enhancement was dose dependent, and was also weaker than that obtained with the same dilution of sera from individuals with chronic or acute infections. Live and dead tachyzoite counts in infected neutrophils suggested a quicker effect of natural IgM antibodies than IgG antibodies elicited by infection.

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Chimeric non-antigen receptors in T cell-based cancer therapy

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-002628 ◽

2021 ◽

Vol 9 (8) ◽

pp. e002628

Author(s):

Jitao Guo ◽

Andrew Kent ◽

Eduardo Davila

Keyword(s):

T Cells ◽

T Cell ◽

Cancer Therapy ◽

Tumor Antigen ◽

Cell Function ◽

Antigen Recognition ◽

Cancer Therapies ◽

Antigen Receptors ◽

Natural Ligands ◽

And Function

Adoptively transferred T cell-based cancer therapies have shown incredible promise in treatment of various cancers. So far therapeutic strategies using T cells have focused on manipulation of the antigen-recognition machinery itself, such as through selective expression of tumor-antigen specific T cell receptors or engineered antigen-recognition chimeric antigen receptors (CARs). While several CARs have been approved for treatment of hematopoietic malignancies, this kind of therapy has been less successful in the treatment of solid tumors, in part due to lack of suitable tumor-specific targets, the immunosuppressive tumor microenvironment, and the inability of adoptively transferred cells to maintain their therapeutic potentials. It is critical for therapeutic T cells to overcome immunosuppressive environmental triggers, mediating balanced antitumor immunity without causing unwanted inflammation or autoimmunity. To address these hurdles, chimeric receptors with distinct signaling properties are being engineered to function as allies of tumor antigen-specific receptors, modulating unique aspects of T cell function without directly binding to antigen themselves. In this review, we focus on the design and function of these chimeric non-antigen receptors, which fall into three broad categories: ‘inhibitory-to-stimulatory’ switch receptors that bind natural ligands, enhanced stimulatory receptors that interact with natural ligands, and synthetic receptor-ligand pairs. Our intent is to offer detailed descriptions that will help readers to understand the structure and function of these receptors, as well as inspire development of additional novel synthetic receptors to improve T cell-based cancer therapy.

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Immunogenicity of NS4b Dengue 3 Virus Mimotope Presented to the Immune System as Multiple Antigen Peptide System

ISRN Virology ◽

10.5402/2013/924057 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Nevis Amin ◽

Maritza Pupo ◽

Alicia Aguilar ◽

Frank Camacho ◽

Mayling Alvarez ◽

...

Keyword(s):

Dengue Virus ◽

Vaccine Design ◽

Amino Acid Sequences ◽

Diagnostic Assays ◽

Random Peptide ◽

Multiple Antigen ◽

Antigen Peptide ◽

Multiple Antigen Peptide ◽

Human Sera ◽

Phage Displayed Peptide Library

The availability of random peptide libraries displayed on bacteriophage (RPL) has provided a powerful tool for selecting sequences that mimic binding properties of natural antigen epitopes (mimotopes). These mimotopes can be used for vaccine design, drug development, and diagnostic assays. Several mimotopes have been shown to induce production of antibodies against the natural antigen. We have previously identified four dengue virus mimotopes from a phage-displayed peptide library using antidengue 3 human sera. Three of them showed similarity in their amino acid sequences with the NS4b proteins of dengue. Few studies have examined the role of NS4b proteins in the antibody response to dengue virus infection. A multiple antigen peptide (MAP) system was chemically synthesized containing this mimotope (NS4b MAP), and BALB/c mice were immunized to evaluate its immunogenicity. Antipeptide responses were induced and recognised DENV-3 infected cells as determined by immunofluorescence. The high levels of the IgG2a subtype against NS4bMAP suggest the induction of a Th1-like response. Our findings suggest that the NS4b mimotope might be a useful tool for the development of multiepitope diagnostic assays, dengue virus vaccine design, and pathogenesis studies.

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Levels of natural IgM antibodies against phosphorylcholine in healthy individuals and in patients undergoing isolated limb perfusion

Journal of Immunological Methods ◽

10.1016/j.jim.2004.06.011 ◽

2004 ◽

Vol 293 (1-2) ◽

pp. 1-11 ◽

Cited By ~ 21

Author(s):

Niubel Diaz Padilla ◽

Caroline Ciurana ◽

Joep van Oers ◽

Aernout C. Ogilvie ◽

C. Erik Hack

Keyword(s):

Isolated Limb Perfusion ◽

Healthy Individuals ◽

Igm Antibodies ◽

Limb Perfusion ◽

Natural Igm

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Circulating Natural IgM Antibodies against Angiogenin in the Peripheral Blood Sera of Patients with Osteosarcoma as Candidate Biomarkers and Reporters of Tumorigenesis

Biomarkers in Cancer ◽

10.4137/bic.s6040 ◽

2010 ◽

Vol 2 ◽

pp. BIC.S6040 ◽

Cited By ~ 4

Author(s):

Yulia A. Savitskaya ◽

Genaro Rico ◽

Luis Linares ◽

Roberto González ◽

René Téllez ◽

...

Keyword(s):

Early Diagnosis ◽

Sensitivity And Specificity ◽

Peripheral Blood ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Healthy Individuals ◽

Igm Antibodies ◽

Potential Biomarker ◽

Increased Risk ◽

Natural Igm

Background Tumor immunology research has led to the identification of a number of tumor-associated self antigens, suggesting that most tumors trigger an immunogenic response, as is the case in osteosarcoma, where the detection of natural serum IgM antibodies might achieve the diagnosis of osteosarcoma. Natural IgM antibodies to tumor-associated proteins may expand the number of available tumor biomarkers for osteosarcoma and may be used together in a serum profile to enhance test sensitivity and specificity. Natural IgM antibodies can be consistently detected in the peripheral blood sera months to years before the tumor is diagnosed clinically. The study of the level of a potential biomarker many months (or years) prior to diagnosis is fundamentally important. Integrated circulating and imaging markers in clinical practice treating osteosarcoma have potential applications for controlling tumor angiogenesis. Objectives To study the expression of natural IgM antibodies to the tumor antigens of angiogenesis in the peripheral blood sera of osteosarcoma patients and healthy individuals, and to develop serum-based predictive biomarkers. Methods Peripheral venous blood samples were collected from 117 osteosarcoma patients and 117 patients with other tumors. All diagnosis was histologically confirmed. Staging of patients was performed according to the Enneking Surgical Staging System. The control group consisted of 117 age- and sex- matched healthy individuals. In this study, novel immunoconjugates were designed, synthesized and then used to develop a rapid, specific and sensitive enzyme-linked immunosorbent assay (ELISA) method to detect angiogenin (ANG)–IgM directly in the peripheral blood sera of humans. Results Serum ANG–IgM levels are significantly higher in osteosarcoma patients than in healthy individuals ( P < 0.005). Serum ANG–IgM levels varied widely, but were highly dependent on the concentration of IgM (r = 0.85; P < 0.0005). We found ANG–IgM in the sera of 85% of newly diagnosed osteosarcoma patients and ANG–IgM levels were significantly higher in osteosarcoma patients compared to any other tumors ( P < 0.001). Conclusions These results demonstrated that the combined biomarker ANG–IgM has greater sensitivity and specificity in early diagnosis of osteosarcoma patients than the traditional biomarkers (ANG and vascular endothelial growth factor). Circulating ANG–IgM immune complexes can potentially serve as a biomarker for increased risk of osteosarcoma, because relatively high serum levels were also detected in otherwise healthy individuals with a first degree family history of osteosarcoma and in patients with a diagnosis of benign conditions. Immunological aspects of angiogenesis for managing osteosarcoma will have a practical value in early diagnosis, prognosis and monitoring response to antiangiogenic therapy.

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Monoclonal antibodies prepared against Dictyostelium actin: characterization and interactions with actin.

The Journal of Cell Biology ◽

10.1083/jcb.99.1.287 ◽

1984 ◽

Vol 99 (1) ◽

pp. 287-295 ◽

Cited By ~ 67

Author(s):

P A Simpson ◽

J A Spudich ◽

P Parham

Keyword(s):

Monoclonal Antibodies ◽

Antigenic Site ◽

Amino Acid Sequences ◽

Cellular Slime Mold ◽

Antigenic Sites ◽

Critical Residue ◽

Slime Mold Dictyostelium Discoideum ◽

Cellular Slime ◽

B Lymphoid ◽

Alpha Actins

Three mouse monoclonal antibodies, Act I, Act II, and Act IV, against actin from the cellular slime mold Dictyostelium discoideum, have been made and characterized. All three antibodies are IgG1 and share the following properties: They form stable complexes with monomeric Dictyostelium actin, which prevents polymerization of the actin into filaments. On addition to preformed actin filaments, they cause a reduction in filament size and in the viscosity of the actin solution. They cross-react strongly with actins from the lower eucaryotes Physarum and Acanthamoeba, but not with alpha-actins from rabbit and human muscle or beta- and gamma-actins from human erythrocytes and a human B lymphoid cell line. Act II and Act IV recognize a similar antigenic determinant that is topographically distinct from that identified by Act I. In protein immunoblotting, only Act I bound strongly to Dictyostelium actin. Analysis of actin fragments with this technique showed that amino acids 13 to about 50 are required for Act I binding to actin. A comparison of the amino acid sequences of actins from lower eucaryotes and higher vertebrates implicates threonine 41 as a critical residue in the Act I antigenic site. The properties of Act II and Act IV suggest that they recognize antigenic sites involving the NH2-terminal six residues.

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In Schizophrenia, Increased Plasma Igm/Iga Responses to Gut Commensal Bacteria are Associated with Negative Symptoms, Neurocognitive Impairments and the Deficit Phenotype

10.20944/preprints201810.0414.v1 ◽

2018 ◽

Author(s):

Michael Maes ◽

Buranee Kanchanatawan ◽

Sunee Sirivichayakul ◽

Andre F. Carvalho

Keyword(s):

Azelaic Acid ◽

Negative Symptoms ◽

Commensal Bacteria ◽

Gram Negative Bacteria ◽

Gram Negative ◽

Deficit Syndrome ◽

Igm Antibodies ◽

Deficit Schizophrenia ◽

Neurocognitive Impairments ◽

Natural Igm

Increased gut permeability (leaky gut) with increased translocation of Gram-negative bacteria plays a role in the gut-brain axis through effects on systemic immune-inflammatory processes. Deficit schizophrenia is characterized by an immune-inflammatory response combined with a deficit in natural IgM antibodies to oxidative specific epitopes (OSEs), which are a first line defense against bacterial infections. This study measured plasma IgA/IgM responses to 5 Gram-negative bacteria in association with IgM responses to malondialdehyde (MDA) and azelaic acid in 80 schizophrenia patients (40 with the deficit syndrome and 40 without) and in 38 healthy controls.Deficit schizophrenia was characterized by significantly increased IgA responses to Hafnei alvei, Pseudomonas aeruginosa, Morganella morganii and Klebsiella pneumoniae as compared with non-deficit schizophrenia. The presence of deficit schizophrenia was highly predicted by increased IgA responses to Pseudomonas putida and IgM responses to all 5 Gram-negative bacteria and lowered natural IgM to MDA and azelaic acid with a bootstrap area under the ROC curve of 0.960 (2000 random curves). A large proportion of the variance (41.5%) in the PANSS negative score was explained by the regression on IgA responses to K. pneumoniae and IgM responses to the 5 enterobacteria coupled with lowered IgM antibodies to azelaic acid. There were significant associations between IgA levels to Gram-negative bacteria and Mini Mental State Examination, Boston naming test, Verbal Fluency and Word List Memory test scores.These findings provide further evidence that deficit schizophrenia is a distinct phenotype of schizophrenia, which is characterized by an increased impact of Gram-negative commensal bacteria coupled with a deficit in natural IgM, pointing to aberrations in B1 cells. It is concluded that increased bacterial translocation and deficits in the compensatory immune-regulatory system (CIRS) may drive negative symptoms and neurocognitive impairments, which are hallmarks of deficit schizophrenia.

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