scholarly journals Analysis of Major Histocompatibility Complex-Bound HIV Peptides Identified from Various Cell Types Reveals Common Nested Peptides and Novel T Cell Responses

2016 ◽  
Vol 90 (19) ◽  
pp. 8605-8620 ◽  
Author(s):  
Marijana Rucevic ◽  
Georgio Kourjian ◽  
Julie Boucau ◽  
Renata Blatnik ◽  
Wilfredo Garcia Bertran ◽  
...  
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
Immune Responses ◽  
Hiv Infection ◽  
Cell Types ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Nested Sets ◽  
Infected Cells ◽  
Hla Molecules

ABSTRACTDespite the critical role of epitope presentation for immune recognition, we still lack a comprehensive definition of HIV peptides presented by HIV-infected cells. Here we identified 107 major histocompatibility complex (MHC)-bound HIV peptides directly from the surface of live HIV-transfected 293T cells, HIV-infected B cells, and primary CD4 T cells expressing a variety of HLAs. The majority of peptides were 8 to 12 amino acids (aa) long and mostly derived from Gag and Pol. The analysis of the total MHC-peptidome and of HLA-A02-bound peptides identified new noncanonical HIV peptides of up to 16 aa that could not be predicted by HLA anchor scanning and revealed an heterogeneous surface peptidome. Nested sets of surface HIV peptides included optimal and extended HIV epitopes and peptides partly overlapping or distinct from known epitopes, revealing new immune responses in HIV-infected persons. Surprisingly, in all three cell types, a majority of Gag peptides derived from p15 rather than from the most immunogenic p24. The cytosolic degradation of peptide precursors in corresponding cells confirmed the generation of identified surface-nested peptides. Cytosolic degradation revealed peptides commonly produced in all cell types and displayed by various HLAs, peptides commonly produced in all cell types and selectively displayed by specific HLAs, and peptides produced in only one cell type. Importantly, we identified areas of proteins leading to common presentations of noncanonical peptides by several cell types with distinct HLAs. These peptides may benefit the design of immunogens, focusing T cell responses on relevant markers of HIV infection in the context of HLA diversity.IMPORTANCEThe recognition of HIV-infected cells by immune T cells relies on the presentation of HIV-derived peptides by diverse HLA molecules at the surface of cells. The landscape of HIV peptides displayed by HIV-infected cells is not well defined. Considering the diversity of HLA molecules in the human population, it is critical for vaccine design to identify HIV peptides that may be displayed despite the HLA diversity. We identified 107 HIV peptides directly from the surface of three cell types infected with HIV. They corresponded to nested sets of HIV peptides of canonical and novel noncanonical lengths not predictable by the presence of HLA anchors. Importantly, we identified areas of HIV proteins leading to presentation of noncanonical peptides by several cell types with distinct HLAs. Including such peptides in vaccine immunogen may help to focus immune responses on common markers of HIV infection in the context of HLA diversity.

scholarly journals Immunization with host-type CD8α+ dendritic cells reduces experimental acute GVHD in an IL-10–dependent manner

Blood ◽  
2010 ◽  
Vol 115 (3) ◽  
pp. 724-735 ◽  
Author(s):  
Tomomi Toubai ◽  
Chelsea Malter ◽  
Isao Tawara ◽  
Chen Liu ◽  
Evelyn Nieves ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Responses ◽  
Class Ii ◽  
Cell Responses ◽  
Histocompatibility Complex

Abstract Little is known about the role of active immunization in suppressing undesirable immune responses. Because CD8α+ dendritic cells (DCs) suppress certain immune responses, we tested the hypothesis that immunization of donors with host-derived CD8α+ DCs will reduce host-specific donor T-cell responses. BALB/c T cells from the animals that were immunized with B6 CD8α+ DCs demonstrated, in vitro and in vivo, significantly reduced proliferation and secretion of inflammatory cytokines but showed enhanced secretion of interleukin-10 (IL-10). The responses against third-party and model antigens were preserved demonstrating antigen specificity. The in vivo relevance was further demonstrated by the reduction on graft-versus-host disease (GVHD) in both a major histocompatibility complex–mismatched clinically relevant BALB/c → B6 model and major histocompatibility complex–matched, minor-mismatched C3H.SW → B6 model of GVHD. Immunization of the donors that were deficient in IL-10 (IL-10−/−) or with CD8α+ DCs from B6 class II (class II−/−) failed to reduce T-cell responses, demonstrating (1) a critical role for secretion of IL-10 by donor T cells and (2) a direct contact between the T cells and the CD8α+ DCs. Together, these data may represent a novel strategy for reducing GVHD and suggest a broad counterintuitive role for vaccination strategies in mitigating undesirable immune responses in an antigen-specific manner.

scholarly journals Molecular and Immunological Significance of Chimpanzee Major Histocompatibility Complex Haplotypes for Hepatitis C Virus Immune Response and Vaccination Studies

2002 ◽  
Vol 76 (12) ◽  
pp. 6093-6103 ◽  
Author(s):  
Eishiro Mizukoshi ◽  
Michelina Nascimbeni ◽  
Joshua B. Blaustein ◽  
Kathleen Mihalik ◽  
Charles M. Rice ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Major Histocompatibility Complex ◽  
Hepatitis C ◽  
Immune Responses ◽  
Cellular Immune Responses ◽  
Functional Homology ◽  
Histocompatibility Complex ◽  
Ifn Γ ◽  
Cellular Immune

ABSTRACT The chimpanzee is a critical animal model for studying cellular immune responses to infectious pathogens such as hepatitis B and C viruses, human immunodeficiency virus, and malaria. Several candidate vaccines and immunotherapies for these infections aim at the induction or enhancement of cellular immune responses against viral epitopes presented by common human major histocompatibility complex (MHC) alleles. To identify and characterize chimpanzee MHC class I molecules that are functionally related to human alleles, we sequenced 18 different Pan troglodytes (Patr) alleles of 14 chimpanzees, 2 of them previously unknown and 3 with only partially reported sequences. Comparative analysis of Patr binding pockets and binding assays with biotinylated peptides demonstrated a molecular homology between the binding grooves of individual Patr alleles and the common human alleles HLA-A1, -A2, -A3, and -B7. Using cytotoxic T cells isolated from the blood of hepatitis C virus (HCV)-infected chimpanzees, we then mapped the Patr restriction of these HCV peptides and demonstrated functional homology between the Patr-HLA orthologues in cytotoxicity and gamma interferon (IFN-γ) release assays. Based on these results, 21 HCV epitopes were selected to characterize the chimpanzees' cellular immune response to HCV. In each case, IFN-γ-producing T cells were detectable in the blood after but not prior to HCV infection and were specifically targeted against those HCV peptides predicted by Patr-HLA homology. This study demonstrates a close functional homology between individual Patr and HLA alleles and shows that HCV infection generates HCV peptides that are recognized by both chimpanzees and humans with Patr and HLA orthologues. These results are relevant for the design and evaluation of vaccines in chimpanzees that can now be selected according to the most frequent human MHC haplotypes.

scholarly journals Resistance of Major Histocompatibility Complex Class B (MHC-B) to Nef-Mediated Downregulation Relative to that of MHC-A Is Conserved among Primate Lentiviruses and Influences Antiviral T Cell Responses in HIV-1-Infected Individuals

2017 ◽  
Vol 92 (1) ◽  
Author(s):  
Francis Mwimanzi ◽  
Mako Toyoda ◽  
Macdonald Mahiti ◽  
Jaclyn K. Mann ◽  
Jeffrey N. Martin ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Immune Responses ◽  
Complex Class ◽  
Subtype C ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Histocompatibility Complex ◽  
Primate Lentiviruses ◽  
Cellular Immune ◽  
Hiv 1

ABSTRACTPatient-derived HIV-1 subtype B Nef clones downregulate HLA-A more efficiently than HLA-B. However, it remains unknown whether this property is common to Nef proteins across primate lentiviruses and how antiviral immune responses may be affected. We examined 263 Nef clones from diverse primate lentiviruses including different pandemic HIV-1 group M subtypes for their ability to downregulate major histocompatibility complex class A (MHC-A) and MHC-B from the cell surface. Though lentiviral Nef proteins differed markedly in their absolute MHC-A and MHC-B downregulation abilities, all lentiviral Nef lineages downregulated MHC-A, on average, 11 to 32% more efficiently than MHC-B. Nef genotype/phenotype analyses in a cohort of HIV-1 subtype C-infected patients (n= 168), together with site-directed mutagenesis, revealed Nef position 9 as a subtype-specific determinant of differential HLA-A versus HLA-B downregulation activity. Nef clones harboring nonconsensus variants at codon 9 downregulated HLA-B (though not HLA-A) significantly better than those harboring the consensus sequence at this site, resulting in reduced recognition of infected target cells by HIV-1-specific CD8+effector cellsin vitro. Among persons expressing protective HLA class I alleles, carriage of Nef codon 9 variants was also associated with reducedex vivoHIV-specific T cell responses. Our results demonstrate that Nef's inferior ability to downregulate MHC-B compared to that of MHC-A is conserved across primate lentiviruses and suggest that this property influences antiviral cellular immune responses.IMPORTANCEPrimate lentiviruses encode the Nef protein that plays an essential role in establishing persistent infection in their respective host species. Nef interacts with the cytoplasmic region of MHC-A and MHC-B molecules and downregulates them from the infected cell surface to escape recognition by host cellular immunity. Using a panel of Nef alleles isolated from diverse primate lentiviruses including pandemic HIV-1 group M subtypes, we demonstrate that Nef proteins across all lentiviral lineages downregulate MHC-A approximately 20% more effectively than MHC-B. We further identify a naturally polymorphic site at Nef position 9 that contributes to the MHC-B downregulation function in HIV-1 subtype C and show that carriage of Nef variants with enhanced MHC-B downregulation ability is associated with reduced breadth and magnitude of MHC-B-restricted cellular immune responses in HIV-infected individuals. Our study underscores an evolutionarily conserved interaction between lentiviruses and primate immune systems that may contribute to pathogenesis.

scholarly journals Presentation of Toxoplasma gondii Antigens via the Endogenous Major Histocompatibility Complex Class I Pathway in Nonprofessional and Professional Antigen-Presenting Cells

2007 ◽  
Vol 75 (11) ◽  
pp. 5200-5209 ◽  
Author(s):  
Florence Dzierszinski ◽  
Marion Pepper ◽  
Jason S. Stumhofer ◽  
David F. LaRosa ◽  
Emma H. Wilson ◽  
...  
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Antigen Processing ◽  
Cell Types ◽  
T Cell Response ◽  
Complex Class ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
Antigen Presenting

ABSTRACT Challenge with the intracellular protozoan parasite Toxoplasma gondii induces a potent CD8+ T-cell response that is required for resistance to infection, but many questions remain about the factors that regulate the presentation of major histocompatibility complex class I (MHC-I)-restricted parasite antigens and about the role of professional and nonprofessional accessory cells. In order to address these issues, transgenic parasites expressing ovalbumin (OVA), reagents that track OVA/MHC-I presentation, and OVA-specific CD8+ T cells were exploited to compare the abilities of different infected cell types to stimulate CD8+ T cells and to define the factors that contribute to antigen processing. These studies reveal that a variety of infected cell types, including hematopoietic and nonhematopoietic cells, are capable of activating an OVA-specific CD8+ T-cell hybridoma, and that this phenomenon is dependent on the transporter associated with antigen processing and requires live T. gondii. Several experimental approaches indicate that T-cell activation is a consequence of direct presentation by infected host cells rather than cross-presentation. Surprisingly, nonprofessional antigen-presenting cells (APCs) were at least as efficient as dendritic cells at activating this MHC-I-restricted response. Studies to assess whether these cells are involved in initiation of the CD8+ T-cell response to T. gondii in vivo show that chimeric mice expressing MHC-I only in nonhematopoietic compartments are able to activate OVA-specific CD8+ T cells upon challenge. These findings associate nonprofessional APCs with the initial activation of CD8+ T cells during toxoplasmosis.

scholarly journals Pol-Specific CD8+ T Cells Recognize Simian Immunodeficiency Virus-Infected Cells Prior to Nef-Mediated Major Histocompatibility Complex Class I Downregulation

2007 ◽  
Vol 81 (21) ◽  
pp. 11703-11712 ◽  
Author(s):  
Jonah B. Sacha ◽  
Chungwon Chung ◽  
Jason Reed ◽  
Anna K. Jonas ◽  
Alexander T. Bean ◽  
...  
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Major Histocompatibility Complex Class ◽  
T Cell Epitopes ◽  
Complex Class ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
Immunodeficiency Virus ◽  
Infected Cells

ABSTRACT Effective, vaccine-induced CD8+ T-cell responses should recognize infected cells early enough to prevent production of progeny virions. We have recently shown that Gag-specific CD8+ T cells recognize simian immunodeficiency virus-infected cells at 2 h postinfection, whereas Env-specific CD8+ T cells do not recognize infected cells until much later in infection. However, it remains unknown when other proteins present in the viral particle are presented to CD8+ T cells after infection. To address this issue, we explored CD8+ T-cell recognition of epitopes derived from two other relatively large virion proteins, Pol and Nef. Surprisingly, infected cells efficiently presented CD8+ T-cell epitopes from virion-derived Pol proteins within 2 h of infection. In contrast, Nef-specific CD8+ T cells did not recognize infected cells until 12 h postinfection. Additionally, we show that SIVmac239 Nef downregulated surface major histocompatibility complex class I (MHC-I) molecules beginning at 12 h postinfection, concomitant with presentation of Nef-derived CD8+ T-cell epitopes. Finally, Pol-specific CD8+ T cells eliminated infected cells as early as 6 h postinfection, well before MHC-I downregulation, suggesting a previously underappreciated antiviral role for Pol-specific CD8+ T cells.

scholarly journals Species specificity and augmentation of responses to class II major histocompatibility complex molecules in human CD4 transgenic mice.

1992 ◽  
Vol 175 (6) ◽  
pp. 1707-1715 ◽  
Author(s):  
E Barzaga-Gilbert ◽  
D Grass ◽  
S K Lawrance ◽  
P A Peterson ◽  
E Lacy ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Class Ii ◽  
T Cell Proliferation ◽  
Human Class ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Species Specific

Murine T cell responses to human class II major histocompatibility complex (MHC) molecules were shown to be a minimum of 20-70-fold lower than responses to allogeneic molecules. Transgenic mice expressing slightly below normal (75-95%) or very high (250-380%) cell surface levels of human CD4 were utilized to determine whether this was due to a species-specific interaction between murine CD4 and class II molecules. Human CD4 was shown to function in signal transduction events in murine T cells based on the ability of anti-human CD4 antibody to synergize with suboptimal doses of anti-murine CD3 antibody in stimulating T cell proliferation. In mice expressing lower levels of human CD4, T cell responses to human class II molecules were enhanced up to threefold, whereas allogeneic responses were unaltered. In mice expressing high levels of human CD4, responses to human class II molecules were enhanced at least 10-fold, whereas allogeneic responses were between one and three times the level of normal responses. The relatively greater enhancement of the response to human class II molecules in both lines argues for a preferential interaction between human CD4 and human class II molecules. In mice expressing lower levels of human CD4, responses to human class II molecules were blocked by antibodies to CD4 of either species, indicating participation by both molecules. In mice expressing high levels of human CD4, responses to both human and murine class II molecules were almost completely blocked with anti-human CD4 antibody, whereas anti-murine CD4 antibody had no effect. However, anti-murine CD4 continued to synergize with anti-CD3 in stimulating T cell proliferation in these mice. Thus, overexpression of human CD4 selectively impaired the ability of murine CD4 to assist in the process of antigen recognition. The ability of human CD4 to support a strong allogeneic response under these conditions indicates that this molecule can interact with murine class II molecules to a significant extent. Despite the fact that human CD4 appeared to be the only functional coreceptor in these mice, responses to human class II molecules were still much lower than those to murine class II alloantigens. This indicates that species-specific interactions between class II molecules and CD4 expressed on peripheral T cells are not sufficient to account for the low xenogeneic response and that intrinsic differences in T cell receptor structures or the need for species specificity in the interaction between CD4 and class II molecules during positive selection are also important.

scholarly journals Major Histocompatibility Complex Class I Gene Controls the Generation of Gamma Interferon-Producing CD4+and CD8+ T Cells Important for Recovery from Friend Retrovirus-Induced Leukemia

2000 ◽  
Vol 74 (11) ◽  
pp. 5363-5367 ◽  
Author(s):  
Karin E. Peterson ◽  
Michihiro Iwashiro ◽  
Kim J. Hasenkrug ◽  
Bruce Chesebro
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
Mhc Class I ◽  
Gamma Interferon ◽  
Class I ◽  
Major Histocompatibility ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Ifn Γ

ABSTRACT Recovery from leukemia induced by Friend virus complex (FV) requires strong CD4+ helper, CD8+ cytotoxic T-lymphocyte, and B-cell responses. The development of these immune responses is dependent on the major histocompatibility complex (MHC) (H-2) genotype of the mouse. InH-2b/b mice, which spontaneously recover from FV-induced erythroleukemia, neutralization of gamma interferon (IFN-γ) in vivo inhibited recovery, which indicated that IFN-γ was a necessary component of the immune response to FV. Furthermore, inH-2b/b mice, high numbers of IFN-γ-producing cells were detected after FV infection, whereas inH-2a/b mice, which have a low-recovery phenotype, only low numbers of IFN-γ-producing cells were detected. Similarly, H-2bm14/b mice, which cannot recover from FV infection due to a point mutation in one allele of theH-2Db gene, also had low numbers of IFN-γ-producing T cells. Surprisingly, this effect was observed for both CD8+ and CD4+ T cells. These findings reveal a novel influence of MHC class I genes on CD4+T-cell responses to viral infection. Furthermore, the influence of MHC class I genotype on the generation of both IFN-γ-producing CD4+ and CD8+ T cells helps explain the major impact of the H-2D gene on recovery from FV disease.

scholarly journals Francisella tularensis Induces Ubiquitin-Dependent Major Histocompatibility Complex Class II Degradation in Activated Macrophages

2009 ◽  
Vol 77 (11) ◽  
pp. 4953-4965 ◽  
Author(s):  
Justin E. Wilson ◽  
Bhuvana Katkere ◽  
James R. Drake
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
T Cell ◽  
Mhc Class Ii ◽  
Francisella Tularensis ◽  
Class Ii ◽  
Activated Macrophages ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Ifn Γ

ABSTRACT The intracellular bacterium Francisella tularensis survives and replicates within macrophages, ultimately killing the host cell. Resolution of infection requires the development of adaptive immunity through presentation of F. tularensis antigens to CD4+ and CD8+ T cells. We have previously established that F. tularensis induces macrophage prostaglandin E2 (PGE2) production, leading to skewed T-cell responses. PGE2 can also downregulate macrophage major histocompatibility complex (MHC) class II expression, suggesting that F. tularensis-elicited PGE2 may further alter T-cell responses via inhibition of class II expression. To test this hypothesis, gamma interferon (IFN-γ)-activated reporter macrophages were exposed to supernatants from F. tularensis-infected macrophages, and the class II levels were measured. Exposure of macrophages to infection supernatants results in essentially complete clearance of surface class II and CD86, compromising the macrophage's ability to present antigens to CD4 T cells. Biochemical analysis revealed that infection supernatants elicit ubiquitin-dependent class II downregulation and degradation within intracellular acidic compartments. By comparison, exposure to PGE2 alone only leads to a minor decrease in macrophage class II expression, demonstrating that a factor distinct from PGE2 is eliciting the majority of class II degradation. However, production of this non-PGE2 factor is dependent on macrophage cyclooxygenase activity and is induced by PGE2. These results establish that F. tularensis induces the production of a PGE2-dependent factor that elicits MHC class II downregulation in IFN-γ-activated macrophages through ubiquitin-mediated delivery of class II to lysosomes, establishing another mechanism for the modulation of macrophage antigen presentation during F. tularensis infection.

Major Histocompatibility Complex (MHC) Tetramer Technology: An Evaluation

2002 ◽  
Vol 4 (2) ◽  
pp. 115-127 ◽  
Author(s):  
Carolyn M. Constantin ◽  
Elizabeth E. Bonney ◽  
John D. Altman ◽  
Ora L. Strickland
Keyword(s):  
Immune Response ◽  
Major Histocompatibility Complex ◽  
Immune Responses ◽  
Single Cell ◽  
Major Histocompatibility ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
Cell Assays ◽  
Mhc Tetramers ◽  
Peptide Complexes

Single-cell assays are currently favored to quantitate T-cell responses. Staining antigen-specific T-cells with fluorescently labeled tetrameric major histocompatibility complex (MHC)/peptide complexes has greatly enhanced the ability to assess the cellular dynamics of an immune response at the single-cell level.This article reviews MHC tetramer technology, defining it, discussing how MHC tetramers are made, outlining the benefits of this technology, comparing and contrasting it to other methods for evaluating immune responses, and describing current applications.

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