Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 110
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Cell ; 158(1): 132-42, 2014 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-24995984

RESUMO

T-cell-mediated hypersensitivity to metal cations is common in humans. How the T cell antigen receptor (TCR) recognizes these cations bound to a major histocompatibility complex (MHC) protein and self-peptide is unknown. Individuals carrying the MHCII allele, HLA-DP2, are at risk for chronic beryllium disease (CBD), a debilitating inflammatory lung condition caused by the reaction of CD4 T cells to inhaled beryllium. Here, we show that the T cell ligand is created when a Be(2+) cation becomes buried in an HLA-DP2/peptide complex, where it is coordinated by both MHC and peptide acidic amino acids. Surprisingly, the TCR does not interact with the Be(2+) itself, but rather with surface changes induced by the firmly bound Be(2+) and an accompanying Na(+) cation. Thus, CBD, by creating a new antigen by indirectly modifying the structure of preexisting self MHC-peptide complex, lies on the border between allergic hypersensitivity and autoimmunity.


Assuntos
Autoimunidade , Beriliose/imunologia , Berílio/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Cadeias beta de HLA-DP/metabolismo , Hipersensibilidade/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Cristalografia por Raios X , Cadeias beta de HLA-DP/química , Humanos , Pulmão/patologia , Modelos Moleculares , Sódio/química , Sódio/metabolismo
2.
Proc Natl Acad Sci U S A ; 121(20): e2320268121, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38709934

RESUMO

Insulin is a central autoantigen in the pathogenesis of T1D, and thymic epithelial cell expression of insulin under the control of the Autoimmune Regulator (Aire) is thought to be a key component of maintaining tolerance to insulin. In spite of this general working model, direct detection of this thymic selection on insulin-specific T cells has been somewhat elusive. Here, we used a combination of highly sensitive T cell receptor transgenic models for detecting thymic selection and sorting and sequencing of Insulin-specific CD4+ T cells from Aire-deficient mice as a strategy to further define their selection. This analysis revealed a number of unique t cell receptor (TCR) clones in Aire-deficient hosts with high affinity for insulin/major histocompatibility complex (MHC) ligands. We then modeled the thymic selection of one of these clones in Aire-deficient versus wild-type hosts and found that this model clone could escape thymic negative selection in the absence of thymic Aire. Together, these results suggest that thymic expression of insulin plays a key role in trimming and removing high-affinity insulin-specific T cells from the repertoire to help promote tolerance.


Assuntos
Proteína AIRE , Insulina , Receptores de Antígenos de Linfócitos T , Timo , Animais , Camundongos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Células Clonais , Tolerância Imunológica , Insulina/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Receptores de Antígenos de Linfócitos T/metabolismo , Receptores de Antígenos de Linfócitos T/imunologia , Timo/imunologia , Timo/metabolismo , Timo/citologia , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética
3.
Immunity ; 45(4): 917-930, 2016 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-27760342

RESUMO

CD8+ T cell recognition of virus-infected cells is characteristically restricted by major histocompatibility complex (MHC) class I, although rare examples of MHC class II restriction have been reported in Cd4-deficient mice and a macaque SIV vaccine trial using a recombinant cytomegalovirus vector. Here, we demonstrate the presence of human leukocyte antigen (HLA) class II-restricted CD8+ T cell responses with antiviral properties in a small subset of HIV-infected individuals. In these individuals, T cell receptor ß (TCRß) analysis revealed that class II-restricted CD8+ T cells underwent clonal expansion and mediated killing of HIV-infected cells. In one case, these cells comprised 12% of circulating CD8+ T cells, and TCRα analysis revealed two distinct co-expressed TCRα chains, with only one contributing to binding of the class II HLA-peptide complex. These data indicate that class II-restricted CD8+ T cell responses can exist in a chronic human viral infection, and may contribute to immune control.


Assuntos
Antivirais/imunologia , Linfócitos T CD8-Positivos/imunologia , Infecções por HIV/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Antígenos HLA/imunologia , Humanos
4.
Proc Natl Acad Sci U S A ; 118(23)2021 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-34074778

RESUMO

Tumors frequently express unmutated self-tumor-associated antigens (self-TAAs). However, trial results using self-TAAs as vaccine targets against cancer are mixed, often attributed to deletion of T cells with high-affinity receptors (TCRs) for self-TAAs during T cell development. Mutating these weak self-TAAs to produce higher affinity, effective vaccines is challenging, since the mutations may not benefit all members of the broad self-TAA-specific T cell repertoire. We previously identified a common weak murine self-TAA that we converted to a highly effective antitumor vaccine by a single amino acid substitution. In this case the modified and natural self-TAAs still raised very similar sets of CD8 T cells. Our structural studies herein show that the modification of the self-TAA resulted in a subtle change in the major histocompatibility complex I-TAA structure. This amino acid substitution allowed a dramatic conformational change in the peptide during subsequent TCR engagement, creating a large increase in TCR affinity and accounting for the efficacy of the modified self-TAA as a vaccine. These results show that carefully selected, well-characterized modifications to a poorly immunogenic self-TAA can rescue the immune response of the large repertoire of weakly responding natural self-TAA-specific CD8 T cells, driving them to proliferate and differentiate into functional effectors. Subsequently, the unmodified self-TAA on the tumor cells, while unable to drive this response, is nevertheless a sufficient target for the CD8 cytotoxic effectors. Our results suggest a pathway for more efficiently identifying variants of common self-TAAs, which could be useful in vaccine development, complementing other current nonantigen-specific immunotherapies.


Assuntos
Antígenos de Neoplasias/imunologia , Autoantígenos/imunologia , Linfócitos T CD8-Positivos/imunologia , Neoplasias Experimentais/imunologia , Peptídeos/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Animais , Vacinas Anticâncer/imunologia , Linhagem Celular Tumoral , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias Experimentais/prevenção & controle , Células Sf9 , Spodoptera
5.
Nat Immunol ; 11(3): 225-31, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20139986

RESUMO

Autoreactive CD4(+) T cells are involved in the pathogenesis of many autoimmune diseases, but the antigens that stimulate their responses have been difficult to identify and in most cases are not well defined. In the nonobese diabetic (NOD) mouse model of type 1 diabetes, we have identified the peptide WE14 from chromogranin A (ChgA) as the antigen for highly diabetogenic CD4(+) T cell clones. Peptide truncation and extension analysis shows that WE14 bound to the NOD mouse major histocompatibility complex class II molecule I-A(g7) in an atypical manner, occupying only the carboxy-terminal half of the I-A(g7) peptide-binding groove. This finding extends the list of T cell antigens in type 1 diabetes and supports the idea that autoreactive T cells respond to unusually presented self peptides.


Assuntos
Autoantígenos/imunologia , Cromogranina A/imunologia , Diabetes Mellitus Tipo 1/imunologia , Células Secretoras de Insulina/imunologia , Fragmentos de Peptídeos/imunologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Epitopos/imunologia , Antígenos HLA-A , Espectrometria de Massas , Camundongos , Camundongos Endogâmicos NOD , Camundongos Knockout , Dados de Sequência Molecular
6.
Proc Natl Acad Sci U S A ; 116(44): 22252-22261, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-31570608

RESUMO

The repertoire of αß T cell antigen receptors (TCRs) on mature T cells is selected in the thymus where it is rendered both self-tolerant and restricted to the recognition of major histocompatibility complex molecules presenting peptide antigens (pMHC). It remains unclear whether germline TCR sequences exhibit an inherent bias to interact with pMHC prior to selection. Here, we isolated TCR libraries from unselected thymocytes and upon reexpression of these random TCR repertoires in recipient T cell hybridomas, interrogated their reactivities to antigen-presenting cell lines. While these random TCR combinations could potentially have reacted with any surface molecule on the cell lines, the hybridomas were stimulated most frequently by pMHC ligands. The nature and CDR3 loop composition of the TCRß chain played a dominant role in determining pMHC-reactivity. Replacing the germline regions of mouse TCRß chains with those of other jawed vertebrates preserved reactivity to mouse pMHC. Finally, introducing the CD4 coreceptor into the hybridomas increased the proportion of cells that could respond to pMHC ligands. Thus, αß TCRs display an intrinsic and evolutionary conserved bias for pMHC molecules in the absence of any selective pressure, which is further strengthened in the presence of coreceptors.


Assuntos
Evolução Molecular , Antígenos de Histocompatibilidade/metabolismo , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Motivos de Aminoácidos , Animais , Linhagem Celular , Células Cultivadas , Antígenos de Histocompatibilidade/química , Antígenos de Histocompatibilidade/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Ligação Proteica , Receptores de Antígenos de Linfócitos T alfa-beta/química , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Seleção Genética
7.
Int J Mol Sci ; 23(19)2022 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-36232627

RESUMO

The SARS-CoV-2 Delta and Lambda variants had been named variants of concern (VOC) and variants of interest (VOI), respectively, by the World Health Organization (WHO). Both variants have two mutations in the spike receptor binding domain (RBD) region, with L452R and T478K mutations in the Delta variant, and L452Q and F490S mutations in the Lambda variant. We used surface plasmon resonance (SPR)-based technology to evaluate the effect of these mutations on human angiotensin-converting enzyme 2 (ACE2) and Bamlanivimab binding. The affinity for the RBD ligand, ACE2, of the Delta RBD is approximately twice as strong as that of the wild type RBD, an increase that accounts for the increased infectivity of the Delta variant. On the other hand, in spite of its amino acid changes, the Lambda RBD has similar affinity to ACE2 as the wild type RBD. The protective anti-wild type RBD antibody Bamlanivimab binds very poorly to the Delta RBD and not at all to the Lambda RBD. Nevertheless, serum antibodies from individuals immunized with the BNT162b2 vaccine were found to bind well to the Delta RBD, but less efficiently to the Lambda RBD in contrast. As a result, the blocking ability of ACE2 binding by serum antibodies was decreased more by the Lambda than the Delta RBD. Titers of sera from BNT162b2 mRNA vaccinated individuals dropped 3-fold within six months of vaccination regardless of whether the target RBD was wild type, Delta or Lambda. This may account partially for the fall off with time in the protective effect of vaccines against any variant.


Assuntos
COVID-19 , SARS-CoV-2 , Aminoácidos , Enzima de Conversão de Angiotensina 2/genética , Anticorpos Monoclonais Humanizados , Anticorpos Neutralizantes , Vacina BNT162 , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Humanos , Imunidade Humoral , Ligantes , Mutação , RNA Mensageiro , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética , Vacinas Sintéticas , Vacinas de mRNA
8.
Immunology ; 162(1): 68-83, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32931017

RESUMO

Memory T cells respond rapidly in part because they are less reliant on a heightened levels of costimulatory molecules. This enables rapid control of secondary infecting pathogens but presents challenges to efforts to control or silence memory CD4 T cells, for example in antigen-specific tolerance strategies for autoimmunity. We have examined the transcriptional and functional consequences of reactivating memory CD4 T cells in the absence of an adjuvant. We find that memory CD4 T cells generated by infection or immunisation survive secondary activation with antigen delivered without adjuvant, regardless of their location in secondary lymphoid organs or peripheral tissues. These cells were, however, functionally altered following a tertiary immunisation with antigen and adjuvant, proliferating poorly but maintaining their ability to produce inflammatory cytokines. Transcriptional and cell cycle analysis of these memory CD4 T cells suggests they are unable to commit fully to cell division potentially because of low expression of DNA repair enzymes. In contrast, these memory CD4 T cells could proliferate following tertiary reactivation by viral re-infection. These data indicate that antigen-specific tolerogenic strategies must examine multiple parameters of Tcell function, and provide insight into the molecular mechanisms that may lead to deletional tolerance of memory CD4 T cells.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Tolerância Imunológica/imunologia , Memória Imunológica/imunologia , Animais , Antígenos/imunologia , Autoimunidade/imunologia , Ciclo Celular/imunologia , Proliferação de Células/fisiologia , Citocinas/imunologia , Reparo do DNA/imunologia , Feminino , Inflamação/imunologia , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Transcrição Gênica/imunologia
9.
Am J Respir Crit Care Med ; 202(7): 1013-1023, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32501729

RESUMO

Rationale: A subpopulation of B cells (age-associated B cells [ABCs]) is increased in mice and humans with infections or autoimmune diseases. Because depletion of these cells might be valuable in patients with certain lung diseases, the goal was to find out if ABC-like cells were at elevated levels in such patients.Objectives: To measure ABC-like cell percentages in patients with lung granulomatous diseases.Methods: Peripheral blood and BAL cells from patients with sarcoidosis, beryllium sensitivity, or hypersensitivity pneumonitis and healthy subjects were analyzed for the percentage of B cells that were ABC-like, defined by expression of CD11c, low levels of CD21, FcRL 1-5 (Fc receptor-like protein 1-5) expression, and, in some cases, T-bet.Measurements and Main Results: ABC-like cells in blood were at low percentages in healthy subjects and higher percentages in patients with sarcoidosis as well as at high percentages among BAL cells of patients with sarcoidosis, beryllium disease, and hypersensitivity pneumonitis. Treatment of patients with sarcoidosis led to reduced percentages of ABC-like cells in blood.Conclusions: Increased levels of ABC-like cells in patients with sarcoidosis may be useful in diagnosis. The increase in percentage of ABC-like cells in patients with lung granulomatous diseases and decrease in treated patients suggests that depletion of these cells may be valuable.


Assuntos
Alveolite Alérgica Extrínseca/sangue , Subpopulações de Linfócitos B/metabolismo , Beriliose/sangue , Líquido da Lavagem Broncoalveolar/citologia , Sarcoidose Pulmonar/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Alveolite Alérgica Extrínseca/imunologia , Subpopulações de Linfócitos B/imunologia , Beriliose/imunologia , Antígeno CD11c/metabolismo , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Proteínas de Membrana/metabolismo , Pessoa de Meia-Idade , Receptores de Superfície Celular/metabolismo , Receptores de Complemento 3d/metabolismo , Receptores Fc/metabolismo , Receptores Imunológicos/metabolismo , Sarcoidose Pulmonar/imunologia , Proteínas com Domínio T/metabolismo , Adulto Jovem
10.
Proc Natl Acad Sci U S A ; 115(1): 162-167, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29255035

RESUMO

A polymorphism at ß57 in some major histocompatibility complex class II (MHCII) alleles of rodents and humans is associated with a high risk for developing type 1 diabetes (T1D). However, a highly diabetogenic insulin B chain epitope within the B:9-23 peptide is presented poorly by these alleles to a variety of mouse and human CD4 T cells isolated from either nonobese diabetic (NOD) mice or humans with T1D. We have shown for both species that mutations at the C-terminal end of this epitope dramatically improve presentation to these T cells. Here we present the crystal structures of these mutated peptides bound to mouse IAg7 and human HLA-DQ8 that show how the mutations function to improve T-cell activation. In both peptide binding grooves, the mutation of B:22R to E in the peptide changes a highly unfavorable side chain for the p9 pocket to an optimal one that is dependent on the ß57 polymorphism, accounting for why these peptides bind much better to these MHCIIs. Furthermore, a second mutation of the adjacent B:21 (E to G) removes a side chain from the surface of the complex that is highly unfavorable for a subset of NOD mouse CD4 cells, thereby greatly enhancing their response to the complex. These results point out the similarities between the mouse and human responses to this B chain epitope in T1D and suggest there may be common posttranslational modifications at the C terminus of the peptide in vivo to create the pathogenic epitopes in both species.


Assuntos
Diabetes Mellitus Tipo 1 , Epitopos , Antígenos HLA-DQ , Antígenos de Histocompatibilidade Classe II , Insulina , Processamento de Proteína Pós-Traducional/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/imunologia , Epitopos/química , Epitopos/genética , Epitopos/imunologia , Antígenos HLA-DQ/química , Antígenos HLA-DQ/genética , Antígenos HLA-DQ/imunologia , Antígenos de Histocompatibilidade Classe II/química , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/imunologia , Humanos , Insulina/química , Insulina/genética , Insulina/imunologia , Camundongos , Camundongos Endogâmicos NOD , Ligação Proteica
11.
Immunity ; 35(4): 526-35, 2011 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-21962492

RESUMO

αß T cell receptors (TCRs) bind specifically to foreign antigens presented by major histocompatibility complex proteins (MHC) or MHC-like molecules. Accumulating evidence indicates that the germline-encoded TCR segments have features that promote binding to MHC and MHC-like molecules, suggesting coevolution between TCR and MHC molecules. Here, we assess directly the evolutionary conservation of αß TCR specificity for MHC. Sequence comparisons showed that some Vßs from distantly related jawed vertebrates share amino acids in their complementarity determining region 2 (CDR2). Chimeric TCRs containing amphibian, bony fish, or cartilaginous fish Vßs can recognize antigens presented by mouse MHC class II and CD1d (an MHC-like protein), and this recognition is dependent upon the shared CDR2 amino acids. These results indicate that features of the TCR that control specificity for MHC and MHC-like molecules were selected early in evolution and maintained between species that last shared a common ancestor more than 400 million years ago.


Assuntos
Evolução Molecular , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Especificidade do Receptor de Antígeno de Linfócitos T , Sequência de Aminoácidos , Animais , Antígenos de Histocompatibilidade Classe II/química , Antígenos de Histocompatibilidade Classe II/imunologia , Humanos , Receptores de Antígenos de Linfócitos T alfa-beta/química , Timo/imunologia
12.
Immunity ; 35(1): 23-33, 2011 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-21683626

RESUMO

Major histocompatibility complex class I (MHCI) and MHCII proteins differ in structure and sequence. To understand how T cell receptors (TCRs) can use the same set of variable regions to bind both proteins, we have presented a comparison of a single TCR bound to both MHCI and MHCII ligands. The TCR adopts similar orientations on both ligands with TCR amino acids thought to be evolutionarily conserved for MHC interaction occupying similar positions on the MHCI and MHCII helices. However, the TCR antigen-binding loops use different conformations when interacting with each ligand. Most importantly, we observed alternate TCR core conformations. When bound to MHCI, but not MHCII, Vα disengages from the Jα ß strand, switching Vα's position relative to Vß. In several other structures, either Vα or Vß undergoes this same modification. Thus, both TCR V-domains can switch among alternate conformations, perhaps extending their ability to react with different MHC-peptide ligands.


Assuntos
Antígenos/metabolismo , Glicoproteínas/metabolismo , Antígenos H-2/metabolismo , Antígenos de Histocompatibilidade Classe II/metabolismo , Fragmentos de Peptídeos/metabolismo , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Animais , Antígenos/genética , Antígenos/imunologia , Proliferação de Células , Células Cultivadas , Regiões Determinantes de Complementaridade/genética , Reações Cruzadas/imunologia , Cristalografia por Raios X , Mapeamento de Epitopos , Glicoproteínas/genética , Glicoproteínas/imunologia , Antígenos H-2/genética , Antígenos H-2/imunologia , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/imunologia , Camundongos , Camundongos Transgênicos , Modelos Moleculares , Mutagênese Sítio-Dirigida , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/imunologia , Ligação Proteica/genética , Ligação Proteica/imunologia , Conformação Proteica , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Linfócitos T
13.
Proc Natl Acad Sci U S A ; 114(37): E7717-E7726, 2017 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-28847961

RESUMO

Two of the unsolved, important questions about epigenetics are: do histone arginine demethylases exist, and is the removal of histone tails by proteolysis a major epigenetic modification process? Here, we report that two orphan Jumonji C domain (JmjC)-containing proteins, JMJD5 and JMJD7, have divalent cation-dependent protease activities that preferentially cleave the tails of histones 2, 3, or 4 containing methylated arginines. After the initial specific cleavage, JMJD5 and JMJD7, acting as aminopeptidases, progressively digest the C-terminal products. JMJD5-deficient fibroblasts exhibit dramatically increased levels of methylated arginines and histones. Furthermore, depletion of JMJD7 in breast cancer cells greatly decreases cell proliferation. The protease activities of JMJD5 and JMJD7 represent a mechanism for removal of histone tails bearing methylated arginine residues and define a potential mechanism of transcription regulation.


Assuntos
Histona Desmetilases/metabolismo , Histonas/metabolismo , Histona Desmetilases com o Domínio Jumonji/metabolismo , Animais , Arginina/metabolismo , Proliferação de Células/fisiologia , Células Cultivadas , Epigênese Genética , Fibroblastos/metabolismo , Histonas/genética , Humanos , Metilação , Camundongos Knockout , Processamento de Proteína Pós-Traducional
14.
Proc Natl Acad Sci U S A ; 113(38): E5608-17, 2016 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-27588903

RESUMO

The interaction of αß T-cell antigen receptors (TCRs) with peptides bound to MHC molecules lies at the center of adaptive immunity. Whether TCRs have evolved to react with MHC or, instead, processes in the thymus involving coreceptors and other molecules select MHC-specific TCRs de novo from a random repertoire is a longstanding immunological question. Here, using nuclease-targeted mutagenesis, we address this question in vivo by generating three independent lines of knockin mice with single-amino acid mutations of conserved class II MHC amino acids that often are involved in interactions with the germ-line-encoded portions of TCRs. Although the TCR repertoire generated in these mutants is similar in size and diversity to that in WT mice, the evolutionary bias of TCRs for MHC is suggested by a shift and preferential use of some TCR subfamilies over others in mice expressing the mutant class II MHCs. Furthermore, T cells educated on these mutant MHC molecules are alloreactive to each other and to WT cells, and vice versa, suggesting strong functional differences among these repertoires. Taken together, these results highlight both the flexibility of thymic selection and the evolutionary bias of TCRs for MHC.


Assuntos
Antígenos de Histocompatibilidade Classe II/genética , Complexo Principal de Histocompatibilidade/genética , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Sequência de Aminoácidos/genética , Animais , Células Germinativas/metabolismo , Antígenos de Histocompatibilidade Classe II/imunologia , Complexo Principal de Histocompatibilidade/imunologia , Camundongos , Peptídeos/genética , Peptídeos/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Linfócitos T/imunologia , Timo/imunologia , Timo/metabolismo
15.
Proc Natl Acad Sci U S A ; 113(29): 8272-7, 2016 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-27307436

RESUMO

Infiltration of T cells in breast tumors correlates with improved survival of patients with breast cancer, despite relatively few mutations in these tumors. To determine if T-cell specificity can be harnessed to augment immunotherapies of breast cancer, we sought to identify the alpha-beta paired T-cell receptors (TCRs) of tumor-infiltrating lymphocytes shared between multiple patients. Because TCRs function as heterodimeric proteins, we used an emulsion-based RT-PCR assay to link and amplify TCR pairs. Using this assay on engineered T-cell hybridomas, we observed ∼85% accurate pairing fidelity, although TCR recovery frequency varied. When we applied this technique to patient samples, we found that for any given TCR pair, the dominant alpha- or beta-binding partner comprised ∼90% of the total binding partners. Analysis of TCR sequences from primary tumors showed about fourfold more overlap in tumor-involved relative to tumor-free sentinel lymph nodes. Additionally, comparison of sequences from both tumors of a patient with bilateral breast cancer showed 10% overlap. Finally, we identified a panel of unique TCRs shared between patients' tumors and peripheral blood that were not found in the peripheral blood of controls. These TCRs encoded a range of V, J, and complementarity determining region 3 (CDR3) sequences on the alpha-chain, and displayed restricted V-beta use. The nucleotides encoding these shared TCR CDR3s varied, suggesting immune selection of this response. Harnessing these T cells may provide practical strategies to improve the shared antigen-specific response to breast cancer.


Assuntos
Neoplasias da Mama/genética , Receptores de Antígenos de Linfócitos T/genética , Linfócitos T/metabolismo , Sequência de Bases , Linhagem Celular , Emulsões , Feminino , Humanos , Reação em Cadeia da Polimerase/métodos
16.
Immunity ; 31(6): 897-908, 2009 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-20064448

RESUMO

T cells often alloreact with foreign human leukocyte antigens (HLA). Here we showed the LC13 T cell receptor (TCR), selected for recognition on self-HLA-B( *)0801 bound to a viral peptide, alloreacts with B44 allotypes (HLA-B( *)4402 and HLA-B( *)4405) bound to two different allopeptides. Despite extensive polymorphism between HLA-B( *)0801, HLA-B( *)4402, and HLA-B( *)4405 and the disparate sequences of the viral and allopeptides, the LC13 TCR engaged these peptide-HLA (pHLA) complexes identically, accommodating mimicry of the viral peptide by the allopeptide. The viral and allopeptides adopted similar conformations only after TCR ligation, revealing an induced-fit mechanism of molecular mimicry. The LC13 T cells did not alloreact against HLA-B( *)4403, and the single residue polymorphism between HLA-B( *)4402 and HLA-B( *)4403 affected the plasticity of the allopeptide, revealing that molecular mimicry was associated with TCR specificity. Accordingly, molecular mimicry that is HLA and peptide dependent is a mechanism for human T cell alloreactivity between disparate cognate and allogeneic pHLA complexes.


Assuntos
Antígenos Nucleares do Vírus Epstein-Barr/imunologia , Antígenos HLA-B/imunologia , Mimetismo Molecular/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/imunologia , Linhagem Celular , Antígeno HLA-B8 , Humanos , Células Jurkat , Ativação Linfocitária/imunologia , Peptídeos/química , Peptídeos/imunologia , Receptores de Antígenos de Linfócitos T/química , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/metabolismo , Transfecção
17.
J Immunol ; 196(1): 22-7, 2016 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26685315

RESUMO

Chronic beryllium (Be) disease is a granulomatous lung disorder that results from Be exposure in a genetically susceptible host. The disease is characterized by the accumulation of Be-responsive CD4(+) T cells in the lung, and genetic susceptibility is primarily linked to HLA-DPB1 alleles possessing a glutamic acid at position 69 of the ß-chain. Recent structural analysis of a Be-specific TCR interacting with a Be-loaded HLA-DP2-peptide complex revealed that Be is coordinated by amino acid residues derived from the HLA-DP2 ß-chain and peptide and showed that the TCR does not directly interact with the Be(2+) cation. Rather, the TCR recognizes a modified HLA-DP2-peptide complex with charge and conformational changes. Collectively, these findings provide a structural basis for the development of this occupational lung disease through the ability of Be to induce posttranslational modifications in preexisting HLA-DP2-peptide complexes, resulting in the creation of neoantigens.


Assuntos
Beriliose/genética , Beriliose/imunologia , Berílio/imunologia , Linfócitos T CD4-Positivos/imunologia , Cadeias beta de HLA-DP/imunologia , Predisposição Genética para Doença , Cadeias beta de HLA-DP/genética , Humanos , Hipersensibilidade/genética , Hipersensibilidade/imunologia , Pulmão/imunologia , Pulmão/patologia , Processamento de Proteína Pós-Traducional/genética , Receptores de Antígenos de Linfócitos T/imunologia
18.
J Immunol ; 197(4): 1221-30, 2016 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-27357147

RESUMO

Aluminum salt (alum) adjuvants have been used for many years as adjuvants for human vaccines because they are safe and effective. Despite its widespread use, the means by which alum acts as an adjuvant remains poorly understood. Recently, it was shown that injected alum is rapidly coated with host chromatin within mice. Experiments suggested that the host DNA in the coating chromatin contributed to alum's adjuvant activity. Some of the experiments used commercially purchased DNase and showed that coinjection of these DNase preparations with alum and Ag reduced the host's immune response to the vaccine. In this study, we report that some commercial DNase preparations are contaminated with proteases. These proteases are responsible for most of the ability of DNase preparations to inhibit alum's adjuvant activity. Nevertheless, DNase somewhat reduces responses to some Ags with alum. The effect of DNase is independent of its ability to cleave DNA, suggesting that alum improves CD4 responses to Ag via a pathway other than host DNA sensing.


Assuntos
Adjuvantes Imunológicos/farmacologia , Compostos de Alúmen/farmacologia , Desoxirribonucleases , Ativação Linfocitária/imunologia , Vacinas/imunologia , Animais , Antígenos/imunologia , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/imunologia , DNA/imunologia , Desoxirribonucleases/química , Desoxirribonucleases/imunologia , Desoxirribonucleases/farmacologia , Contaminação de Medicamentos , Ensaio de Imunoadsorção Enzimática , Feminino , Ativação Linfocitária/efeitos dos fármacos , Espectrometria de Massas , Camundongos , Camundongos Endogâmicos C57BL
19.
Proc Natl Acad Sci U S A ; 112(43): 13318-23, 2015 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-26453556

RESUMO

Chromogranin A (ChgA) is an autoantigen for CD4(+) T cells in the nonobese diabetic (NOD) mouse model of type 1 diabetes (T1D). The natural ChgA-processed peptide, WE14, is a weak agonist for the prototypical T cell, BDC-2.5, and other ChgA-specific T-cell clones. Mimotope peptides with much higher activity share a C-terminal motif, WXRM(D/E), that is predicted to lie in the p5 to p9 position in the mouse MHC class II, IA(g7) binding groove. This motif is also present in WE14 (WSRMD), but at its N terminus. Therefore, to place the WE14 motif into the same position as seen in the mimotopes, we added the amino acids RLGL to its N terminus. Like the other mimotopes, RLGL-WE14, is much more potent than WE14 in T-cell stimulation and activates a diverse population of CD4(+) T cells, which also respond to WE14 as well as islets from WT, but not ChgA(-/-) mice. The crystal structure of the IA(g7)-RLGL-WE14 complex confirmed the predicted placement of the peptide within the IA(g7) groove. Fluorescent IA(g7)-RLGL-WE14 tetramers bind to ChgA-specific T-cell clones and easily detect ChgA-specific T cells in the pancreas and pancreatic lymph nodes of NOD mice. The prediction that many different N-terminal amino acid extensions to the WXRM(D/E) motif are sufficient to greatly improve T-cell stimulation leads us to propose that such a posttranslational modification may occur uniquely in the pancreas or pancreatic lymph nodes, perhaps via the mechanism of transpeptidation. This modification could account for the escape of these T cells from thymic negative selection.


Assuntos
Autoantígenos/imunologia , Cromogranina A/química , Cromogranina A/imunologia , Diabetes Mellitus Tipo 1/imunologia , Epitopos/imunologia , Modelos Moleculares , Fragmentos de Peptídeos/imunologia , Sequência de Aminoácidos , Animais , Baculoviridae/genética , Sequência de Bases , Cromogranina A/genética , Cristalização , Epitopos/genética , Citometria de Fluxo , Hibridomas/imunologia , Interleucina-2/imunologia , Camundongos , Camundongos Endogâmicos NOD , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Processamento de Proteína Pós-Traducional/genética
20.
Proc Natl Acad Sci U S A ; 112(14): 4429-34, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25831495

RESUMO

Certain class II MHC (MHCII) alleles in mice and humans confer risk for or protection from type 1 diabetes (T1D). Insulin is a major autoantigen in T1D, but how its peptides are presented to CD4 T cells by MHCII risk alleles has been controversial. In the mouse model of T1D, CD4 T cells respond to insulin B-chain peptide (B:9-23) mimotopes engineered to bind the mouse MHCII molecule, IA(g7), in an unfavorable position or register. Because of the similarities between IA(g7) and human HLA-DQ T1D risk alleles, we examined control and T1D subjects with these risk alleles for CD4 T-cell responses to the same natural B:9-23 peptide and mimotopes. A high proportion of new-onset T1D subjects mounted an inflammatory IFN-γ response much more frequently to one of the mimotope peptides than to the natural peptide. Surprisingly, the control subjects bearing an HLA-DQ risk allele also did. However, these control subjects, especially those with only one HLA-DQ risk allele, very frequently made an IL-10 response, a cytokine associated with regulatory T cells. T1D subjects with established disease also responded to the mimotope rather than the natural B:9-23 peptide in proliferation assays and the proliferating cells were highly enriched in certain T-cell receptor sequences. Our results suggest that the risk of T1D may be related to how an HLA-DQ genotype determines the balance of T-cell inflammatory vs. regulatory responses to insulin, having important implications for the use and monitoring of insulin-specific therapies to prevent diabetes onset.


Assuntos
Linfócitos T CD4-Positivos/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Inflamação/metabolismo , Insulina/genética , Insulina/metabolismo , Adolescente , Adulto , Sequência de Aminoácidos , Animais , Autoanticorpos/metabolismo , Criança , Citocinas/metabolismo , Feminino , Genótipo , Antígenos HLA-DQ/genética , Humanos , Interferon gama/metabolismo , Interleucina-10/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos NOD , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação , Receptores de Antígenos de Linfócitos T/metabolismo , Homologia de Sequência de Aminoácidos , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA