scholarly journals The heme moiety of cytochrome c is an autoreactive Ir gene-restricted T cell epitope.

1988 ◽  
Vol 168 (3) ◽  
pp. 1127-1143 ◽  
Author(s):  
H M Cooper ◽  
G Corradin ◽  
Y Paterson
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
T Cell ◽  
Proliferative Response ◽  
Cell Epitope ◽  
Cell Populations ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Cell Clones ◽  
Cyt C

In these studies, we have shown that the heme moiety of cyt c is a dominant T cell epitope that induces a large proliferative response in lymph node T cells derived from SJL and B10.A mice when presented on either unfixed or fixed syngeneic APCs. Not only is this vigorous response observed for cyt c-primed T cell populations but also for populations obtained from naive SJL or B10.A mice. The reactivity to the heme moiety falls under strict MHC restriction, in that it is present only in murine strains bearing either the I-Ak or I-As molecule and can be blocked by antibodies specific for these class II molecules. Therefore, these findings require that the current models describing the nature of T cell epitopes be extended to include nonpeptide molecules. Furthermore, as the heme moiety is ubiquitous throughout the organism, although sequestered within proteins, the existence of heme-reactive T cell populations in unprimed animals provides another example of the existence of self-reactive T cell clones.

Factor VIII Proteins Having a Rationally Modified, Immunodominant T-Cell Epitope Demonstrate Normal Procoagulant Activity, Bind To VWF With High Affinity, and Are Markedly Less Stimulatory To FVIII-Specific Human T Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 574-574 ◽  
Author(s):  
Ruth A. Ettinger ◽  
Eddie A. James ◽  
Komal Puranik ◽  
Arthur R. Thompson ◽  
Dana C. Matthews ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Hemophilia A ◽  
Cell Epitope ◽  
Antigen Presenting Cells ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
High Affinity ◽  
Cell Clones ◽  
Antigen Presenting

Abstract Neutralizing anti-factor VIII (FVIII) antibodies, referred to clinically as “inhibitors”, can develop as an alloimmune response in hemophilia A patients receiving FVIII infusions as replacement therapy. Immune Tolerance Induction, consisting of intensive FVIII treatment in an effort to tolerize patients to FVIII, is extraordinarily expensive and not always successful. New approaches to avoid inhibitor development, and to treat patients who develop this deleterious immune response, are needed. Initial stages of inhibitor development include FVIII uptake and processing into peptides by antigen-presenting cells such as dendritic cells (DCs), presentation of FVIII peptides on MHC Class II (HLA) receptors on the cell surface, and recognition of HLA-peptide complexes by one or more circulating T cells. Subsequent signaling through immunological synapses between antigen-presenting cells and T-cell receptors causes proliferation of effector T cells, which secrete cytokines promoting anti-FVIII antibody production. Our laboratory has been identifying T-cell epitopes in FVIII, which are amino acid sequences 11-15 residues long that bind to specific HLA-DR proteins and are in turn recognized by T cells. FVIII 2194-2205 comprises an immunodominant T-cell epitope that binds to HLA-DRB1*01:01. Peptide-MHC binding experiments established that the side chains of amino acid residues F2196, M2199, A2201 and S2204 fit into the HLA-DRB1*01:01 peptide-binding groove, allowing peptides containing this sequence to be presented on the surface of antigen-presenting cells. Fluorescent HLA-DRB1*01:01 tetramers loaded with FVIII2194-2213 were used to stain and isolate FVIII-specific T cells from 3 hemophilia A subjects who had an HLA-DRB1*01:01 allele. These cells were expanded in culture to generate T-cell clones and polyclonal lines that recognize this sequence and proliferate in response to it. Stimulation of clones with FVIII peptides containing systematic alanine substitutions demonstrated that MHC anchor residues F2196 and M2199 are important for the immunogenicity of this T-cell epitope. The clones were then stimulated with FVIII peptides and recombinant FVIII-C2 domain proteins in which F2196 was changed to a series of other residues. The effect of substitutions at M2199 was examined using the ProPred computer prediction program. Three substitutions that significantly reduced T-cell proliferation (F2196A, F2196L, F2196K) or were predicted to do so (M2199A, M2199W, M2199R) were introduced into recombinant, B-domain-deleted (BDD)-FVIII. The present study tests the hypothesis that less immunogenic FVIII proteins having normal FVIII procoagulant activity can be produced through rational modification of T-cell epitopes. The F2196K and M2199A muteins were expressed at levels similar to wild-type (WT)-BDD-FVIII in BHK-M cells and were purified from serum-free BHK-M cell supernatants. Purified CD14-positive monocytes from individuals with the HLA-DRB1*01:01 allele were differentiated into DCs and used for antigen-presentation assays in which 4 hemophilic T-cell clones and 2 polyclonal lines were added to the DCs and stimulated with FVIII2194-2213, WT-FVIII, WT-BDD-FVIII and the BDD-FVIII muteins. One clone proliferated weakly in response to both the WT and mutant proteins, while the remaining 3 clones and 2 lines showed markedly less proliferation in response to the BDD-FVIII muteins. BDD-FVIII-2196K and 2199A had specific activities similar to that of WT-BDD-FVIII (by chromogenic and clotting assays), and surface plasmon resonance confirmed that they retained high-affinity binding to von Willebrand factor. These results provide proof-of-principle for the design of less immunogenic FVIII proteins targeted to specific subsets of hemophilia A patients. Disclosures: Pratt: Bayer, Pfizer, CSL Behring: Research Funding; Puget Sound Blood Center Research Institute: sequence-modified FVIII variants Patents & Royalties.

scholarly journals Antigen-specific T cell clones restricted to unique F(1) major histocompatibility complex determinants. Inhibition of proliferation with a monoclonal anti-Ia antibody

1981 ◽  
Vol 153 (3) ◽  
pp. 677-693 ◽  
Author(s):  
B Sredni ◽  
LA Matis ◽  
EA Lerner ◽  
WE Paul ◽  
RH Schwartz
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Proliferative Response ◽  
Cell Populations ◽  
Gene Products ◽  
Spleen Cells ◽  
Histocompatibility Complex ◽  
Cell Clones ◽  
Antigen Presenting

The existence of T cells specific for soluble antigens in association with unique F(1) or recombinant major histocompatibility complex (MHC) gene products was first postulated from studies on the proliferative response of whole T cell populations to the antigen poly(Glu(55)Lys(36)Phe(9))(n) (GLφ). In this paper we use the newly developed technology of T lymphocyte cloning to establish unequivocally the existence of such cells specific for GLφ and to generalize their existence by showing that F(1)- specific cells can be isolated from T cell populations primed to poly(Glu(60)Ala(30)Tyr(10))(n) (GAT) where such clones represent only a minor subpopulation of cells. Gl.4b-primed B10.A(5R) and GAT-primed (B10.A × B10)F(1) lymph node T cells were cloned in soft agar, and the colonies that developed were picked and expanded in liquid culture. The GLφ-specific T cells were then recloned under conditions of high-plating efficiency to ensure that the final colonies originated from single cells. T cells from such rigorously cloned populations responded to stimulation with GILφ but only in the presence of nonimmune, irradiated spleen cells bearing (B10.A × B10)F(1) or the syngeneic B 10.A(5R) recombinant MHC haplotype. Spleen cells from either the B10 or B 10.A parental strains failed to support a proliferative response, even when added together. (B10 × B10.D2)F(1) and (B10 × B10.RIII)F(1) spleen cells also supported a proliferative response but (B10 × B10.Q)F(1) and (B10 X B10.S)F(1) spleen cells did not. These results suggested that the T cell clones were specific for GL[phi} in association with the β(AE)(b)-α(E) (k,d,r,) Ia molecule and that recognition required both gene products to be expressed in the same antigen-presenting cells. Support for this interpretation was obtained from inhibition experiments using the monoclonal antibody Y-17 specific for a determinant on the β(AE)(b)-αE Ia molecule. Y-17 completely inhibited the proliferative response of a GLφ-specific clone but had no effect on the response of either a PPD-specific or GAT-specific clone, both of which required the β(A)-α(A) Ia molecule as their restriction element. No evidence could be found for the involvement of suppressor T cells in this inhibition. We therefore conclude that the phenomenon of F(1)-restricted recognition by proliferating T cells results from the presence of antigen- specific clones that must recognize unique F(1) or recombinant Ia molecules on the surface of antigen-presenting cells in addition to antigen in order to be stimulated.

scholarly journals The Substrate-Binding Domain of 21-Hydroxylase, the Main Autoantigen in Autoimmune Addison’s Disease, Is an Immunodominant T Cell Epitope

Endocrinology ◽  
2006 ◽  
Vol 147 (5) ◽  
pp. 2411-2416 ◽  
Author(s):  
Eystein S. Husebye ◽  
Eirik Bratland ◽  
Geir Bredholt ◽  
Mati Fridkin ◽  
Molly Dayan ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
T Cell ◽  
Proliferative Response ◽  
Substrate Binding ◽  
Cell Epitope ◽  
Addison’S Disease ◽  
Addison's Disease ◽  
Adrenal Failure ◽  
Lymph Node Cells

The steroidogenic enzyme 21-hydroxylase (21OH) is the main autoantigen in autoimmune primary adrenal failure (Addison’s disease). Autoantibodies against 21OH are immunological markers of an ongoing autoimmune process but are not directly involved in the tissue destruction. Autoreactive T cells are thought to mediate tissue damage, but the T cell antigen(s) has not been identified. To find out whether 21OH contains important immunodominant epitopes for T cells, we first immunized BALB/c and SJL inbred mouse strains with recombinant 21OH and showed that lymph node cells proliferated effectively following in vitro stimulation with recombinant 21OH (stimulation indices (SI) 20–40). We further synthesized a series of peptides based on 21OH with amino acid sequences with propensity to bind to major histocompatibility complex class II molecules. Only a few peptides could trigger lymphocytes of 21OH-primed mice to proliferate. One of these, 21OH (342–361), stimulated effectively 21OH-primed lymph node cells of SJL mice (SI = 4–8) and also, although to a lesser extent, of BALB/c mice (SI = 2.5). When SJL mice were immunized with 21OH (342–361), the immunizing peptide as well as peptide 21OH (346–361) triggered a significant proliferative response (SI = 24). A peptide from another part of 21OH, namely 21OH (191–202), did not stimulate the 21OH (342–361)-primed cells. Moreover, stimulation of lymph node cells of mice immunized with 21OH (342–361) with 21OH resulted in a significant proliferative response. We conclude that 21OH (342–361) is an immunodominant determinant for T cells in SJL and probably BALB/c mice. 21OH (342–361) corresponds to the substrate binding site of the enzyme. The p342–361 region may be involved in the pathogenesis of autoimmune adrenal failure in humans.

scholarly journals Immunogenicity of a Recombinant Influenza Virus Bearing Both the CD4+ and CD8+ T Cell Epitopes of Ovalbumin

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Bruno Garulli ◽  
Giuseppina Di Mario ◽  
Ester Sciaraffia ◽  
Yoshihiro Kawaoka ◽  
Maria R. Castrucci
Keyword(s):  
T Cells ◽  
Influenza Virus ◽  
T Cell ◽  
Cell Epitope ◽  
Cd8 T Cell ◽  
Influenza Viruses ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Additional Tool

Recombinant influenza viruses that bear the single immunodominant CD8+ T cell epitopeOVA257−264or the CD4+ T cell epitopeOVA323−339of the model antigen ovalbumin (OVA) have been useful tools in immunology. Here, we generated a recombinant influenza virus,WSN-OVAI/II, that bears both OVA-specific CD8+ and CD4+ epitopes on its hemagglutinin molecule. Live and heat-inactivatedWSN-OVAI/IIviruses were efficiently presented by dendritic cellsin vitroto OT-I TCR transgenic CD8+ T cells and OT-II TCR transgenic CD4+ T cells.In vivo,WSN-OVAI/IIvirus was attenuated in virulence, highly immunogenic, and protected mice from B16-OVA tumor challenge in a prophylactic model of vaccination. Thus,WSN-OVAI/IIvirus represents an additional tool, along with OVA TCR transgenic mice, for further studies on T cell responses and may be of value in vaccine design.

scholarly journals Swine T-Cells and Specific Antibodies Evoked by Peptide Dendrimers Displaying Different FMDV T-Cell Epitopes

2021 ◽  
Vol 11 ◽  
Author(s):  
Patricia de León ◽  
Rodrigo Cañas-Arranz ◽  
Sira Defaus ◽  
Elisa Torres ◽  
Mar Forner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Cell Epitope ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
B Cell Epitope ◽  
Mouth Disease Virus ◽  
Ifn Γ

Dendrimeric peptide constructs based on a lysine core that comprises both B- and T-cell epitopes of foot-and-mouth disease virus (FMDV) have proven a successful strategy for the development of FMD vaccines. Specifically, B2T dendrimers displaying two copies of the major type O FMDV antigenic B-cell epitope located on the virus capsid [VP1 (140–158)], covalently linked to a heterotypic T-cell epitope from either non-structural protein 3A [3A (21–35)] or 3D [3D (56–70)], named B2T-3A and B2T-3D, respectively, elicit high levels of neutralizing antibodies (nAbs) and IFN-γ-producing cells in pigs. To assess whether the inclusion and orientation of T-3A and T-3D T-cell epitopes in a single molecule could modulate immunogenicity, dendrimers with T epitopes juxtaposed in both possible orientations, i.e., constructs B2TT-3A3D and B2TT-3D3A, were made and tested in pigs. Both dendrimers elicited high nAbs titers that broadly neutralized type O FMDVs, although B2TT-3D3A did not respond to boosting, and induced lower IgGs titers, in particular IgG2, than B2TT-3A3D. Pigs immunized with B2, a control dendrimer displaying two B-cell epitope copies and no T-cell epitope, gave no nABs, confirming T-3A and T-3D as T helper epitopes. The T-3D peptide was found to be an immunodominant, as it produced more IFN-γ expressing cells than T-3A in the in vitro recall assay. Besides, in pigs immunized with the different dendrimeric peptides, CD4+ T-cells were the major subset contributing to IFN-γ expression upon in vitro recall, and depletion of CD4+ cells from PBMCs abolished the production of this cytokine. Most CD4+IFN-γ+ cells showed a memory (CD4+2E3−) and a multifunctional phenotype, as they expressed both IFN-γ and TNF-α, suggesting that the peptides induced a potent Th1 pro-inflammatory response. Furthermore, not only the presence, but also the orientation of T-cell epitopes influenced the T-cell response, as B2TT-3D3A and B2 groups had fewer cells expressing both cytokines. These results help understand how B2T-type dendrimers triggers T-cell populations, highlighting their potential as next-generation FMD vaccines.

T Cell Epitope Predictions

2020 ◽  
Vol 38 (1) ◽  
pp. 123-145 ◽  
Author(s):  
Bjoern Peters ◽  
Morten Nielsen ◽  
Alessandro Sette
Keyword(s):  
T Cells ◽  
T Cell ◽  
Epitope Mapping ◽  
Cell Epitope ◽  
Cell Types ◽  
The Body ◽  
Cell Immune Response ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Mhc Molecules

Throughout the body, T cells monitor MHC-bound ligands expressed on the surface of essentially all cell types. MHC ligands that trigger a T cell immune response are referred to as T cell epitopes. Identifying such epitopes enables tracking, phenotyping, and stimulating T cells involved in immune responses in infectious disease, allergy, autoimmunity, transplantation, and cancer. The specific T cell epitopes recognized in an individual are determined by genetic factors such as the MHC molecules the individual expresses, in parallel to the individual's environmental exposure history. The complexity and importance of T cell epitope mapping have motivated the development of computational approaches that predict what T cell epitopes are likely to be recognized in a given individual or in a broader population. Such predictions guide experimental epitope mapping studies and enable computational analysis of the immunogenic potential of a given protein sequence region.

scholarly journals Mining the capacity of human-associated microorganisms to trigger rheumatoid arthritis—A systematic immunoinformatics analysis of T cell epitopes

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253918
Author(s):  
Jelena Repac ◽  
Marija Mandić ◽  
Tanja Lunić ◽  
Bojan Božić ◽  
Biljana Božić Nedeljković
Keyword(s):  
Rheumatoid Arthritis ◽  
T Cell ◽  
De Novo ◽  
Molecular Mimicry ◽  
Sequence Similarity ◽  
Cell Epitope ◽  
Homology Search ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Painful Condition

Autoimmune diseases, often triggered by infection, affect ~5% of the worldwide population. Rheumatoid Arthritis (RA)–a painful condition characterized by the chronic inflammation of joints—comprises up to 20% of known autoimmune pathologies, with the tendency of increasing prevalence. Molecular mimicry is recognized as the leading mechanism underlying infection-mediated autoimmunity, which assumes sequence similarity between microbial and self-peptides driving the activation of autoreactive lymphocytes. T lymphocytes are leading immune cells in the RA-development. Therefore, deeper understanding of the capacity of microorganisms (both pathogens and commensals) to trigger autoreactive T cells is needed, calling for more systematic approaches. In the present study, we address this problem through a comprehensive immunoinformatics analysis of experimentally determined RA-related T cell epitopes against the proteomes of Bacteria, Fungi, and Viruses, to identify the scope of organisms providing homologous antigenic peptide determinants. By this, initial homology screening was complemented with de novo T cell epitope prediction and another round of homology search, to enable: i) the confirmation of homologous microbial peptides as T cell epitopes based on the predicted binding affinity to RA-related HLA polymorphisms; ii) sequence similarity inference for top de novo T cell epitope predictions to the RA-related autoantigens to reveal the robustness of RA-triggering capacity for identified (micro/myco)organisms. Our study reveals a much larger repertoire of candidate RA-triggering organisms, than previously recognized, providing insights into the underestimated role of Fungi in autoimmunity and the possibility of a more direct involvement of bacterial commensals in RA-pathology. Finally, our study pinpoints Endoplasmic reticulum chaperone BiP as the most potent (most likely mimicked) RA-related autoantigen, opening an avenue for identifying the most potent autoantigens in a variety of different autoimmune pathologies, with possible implications in the design of next-generation therapeutics aiming to induce self-tolerance by affecting highly reactive autoantigens.

scholarly journals In Silico Identification and in Vitro Analysis of B and T-Cell Epitopes of the Black Turtle Bean (Phaseolus Vulgaris L.) Lectin

2018 ◽  
Vol 49 (4) ◽  
pp. 1600-1614 ◽  
Author(s):  
Shudong He ◽  
Jinlong Zhao ◽  
Walid Elfalleh ◽  
Mohamed Jemaà ◽  
Hanju  Sun ◽  
...  
Keyword(s):  
Amino Acids ◽  
T Cell ◽  
Phaseolus Vulgaris ◽  
B Cell ◽  
Cell Epitope ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Phaseolus Vulgaris L ◽  
B Cell Epitopes ◽  
B Cell Epitope

Background/Aims: The incidence of lectin allergic disease is increasing in recent decades, and definitive treatment is still lacking. Identification of B and T-cell epitopes of allergen will be useful in understanding the allergen antibody responses as well as aiding in the development of new diagnostics and therapy regimens for lectin poisoning. In the current study, we mainly addressed these questions. Methods: Three-dimensional structure of the lectin from black turtle bean (Phaseolus vulgaris L.) was modeled using the structural template of Phytohemagglutinin from P. vulgaris (PHA-E, PDB ID: 3wcs.1.A) with high identity. The B and T-cell epitopes were screened and identified by immunoinformatics and subsequently validated by ELISA, lymphocyte proliferation and cytokine profile analyses. Results: Seven potential B-cell epitopes (B1 to B7) were identified by sequence and structure based methods, while three T-cell epitopes (T1 to T3) were identified by the predictions of binding score and inhibitory concentration. The epitope peptides were synthesized. Significant IgE binding capability was found in B-cell epitopes (B2, B5, B6 and B7) and T2 (a cryptic B-cell epitope). T1 and T2 induced significant lymphoproliferation, and the release of IL-4 and IL-5 cytokine confirmed the validity of T-cell epitope prediction. Abundant hydrophobic amino acids were found in B-cell epitope and T-cell epitope regions by amino acid analysis. Positively charged amino acids, such as His residue, might be more favored for B-cell epitope. Conclusion: The present approach can be applied for the identification of epitopes in novel allergen proteins and thus for designing diagnostics and therapies in lectin allergy.

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