Sequence Dependent Efficiency of Cross-Presentation in MHC Class I Requires Rational Design of Long Synthetic Peptides for Vaccination or Ex Vivo Activation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3904-3904
Author(s):  
Maarten L. Zandvliet ◽  
J.H. Frederik Falkenburg ◽  
Michel G.D. Kester ◽  
Arnoud H. de Ru ◽  
Peter A. van Veelen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Synthetic Peptides ◽  
Ex Vivo ◽  
Class I ◽  
Cross Presentation ◽  
Cell Responses

Abstract For the induction or boosting of antigen-specific CD8+ T cell responses, long synthetic peptides have been used in vaccination studies. Superior in vivo CD8+ T cell responses have been reported following vaccination with long peptides compared with minimal peptides, which was attributed to selective uptake and cross-presentation by professional antigen-presenting cells. Furthermore, to generate antigen-specific T cell lines for adoptive immunotherapy or to measure antigen-specific T cell responses, protein-spanning pools of overlapping long synthetic peptides can be used to simultaneously activate CD8+ and CD4+ T cells in peripheral blood mononuclear cells (PBMC) ex vivo. Although exogenous antigen is predominantly presented in MHC class II, it has been suggested that cross-presentation of long peptides in MHC class I can occur. However, the mechanism of cross-presentation of exogenous long peptides in MHC class I is not clear. Various models for cross-presentation have been described following uptake of soluble antigen in endosomes, among which antigen transport over the endosomal membrane followed by the classical proteasome- and TAP-dependent route, and entrance of MHC class I in the recycling endocytic MHC class II pathway where peptidase-trimmed exogenous antigens can exchange with peptides in the MHC class I molecules, resulting in TAP- and proteasome-independent cross-presentation. To improve the design of peptides for the in vivo or ex vivo activation of CD8+ T cells we investigated the mechanism and efficiency of cross-presentation of long peptides. We observed that antigen-presenting cells in peripheral blood, in particular monocytes, loaded with 15-mer peptides, 31-mer peptides or full length protein containing the NLV epitope were able to very efficiently induce IFNg production by cytomegalovirus (CMV) pp65 NLV-specific T cells. Specific T cells were most efficiently activated by N-terminally extended variants of the minimal epitope, while the use of C-terminally extended variants resulted in a 10-fold reduction of activation efficiency. Purification of these antigens by high performance liquid chromatography (HPLC) followed by mass spectrometry demonstrated that activation was not caused by contamination with the minimal epitope sequence. Also CD8+ T cells specific for other CMV and minor histocompatibility antigen (mHag) epitopes were activated by monocytes loaded with 15-mer or 20-mer peptides. Again N-terminally extended variants of minimal epitopes very efficiently induced activation, while the use of C-terminally variants or full length protein resulted in highly variable efficiency of activation, ranging from 10-fold reduction to complete absence of activation. Interestingly, TAP-deficient T2 cells loaded with CMV pp65 NLV antigens also efficiently activated NLV-specific T cells, indicating that the route of presentation was TAP-independent. Addition of lactacystin during loading of monocytes with CMV pp65 NLV 15-mer did not affect activation of specific T cells, suggesting that cross-presentation was proteasome-independent. Addition of primaquine reduced activation of specific T cells by the NLV 15-mer peptide, but not by the minimal NLV 9-mer peptide, suggesting that cross-presentation was dependent on endosomal recycling. To compare cross-presentation with presentation of endogenously synthesized antigen, TAP-competent T1 and TAP-deficient T2 cells were retrovirally transduced with the CMV pp65 gene. CMV pp65-specific T cells were activated by CMV pp65 transduced T1 but not T2 cells, indicating that endogenously synthesized CMV pp65 required processing and presentation by the classical proteasome- and TAP-dependent route. These data suggest that long synthetic peptides can be processed by peptidases in endocytic compartments and presented by recycling MHC class I molecules. Not all immunogenic epitopes that have been selected in vivo for efficient processing and presentation by the classical pathway may be presented efficiently by cross-presentation. As the efficiency of cross-presentation of long synthetic peptides may depend on the sequence of the C-terminal extension, a rational design of peptides is crucial for efficient activation of CD8+ T cells in approaches of vaccination, adoptive transfer and immune monitoring.

scholarly journals Efficient Targeting of Protein Antigen to the Dendritic Cell Receptor DEC-205 in the Steady State Leads to Antigen Presentation on Major Histocompatibility Complex Class I Products and Peripheral CD8+ T Cell Tolerance

2002 ◽  
Vol 196 (12) ◽  
pp. 1627-1638 ◽  
Author(s):  
Laura Bonifaz ◽  
David Bonnyay ◽  
Karsten Mahnke ◽  
Miguel Rivera ◽  
Michel C. Nussenzweig ◽  
...  
Keyword(s):  
T Cells ◽  
Major Histocompatibility Complex ◽  
Steady State ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Class I ◽  
Histocompatibility Complex ◽  
Dc Maturation

To identify endocytic receptors that allow dendritic cells (DCs) to capture and present antigens on major histocompatibility complex (MHC) class I products in vivo, we evaluated DEC-205, which is abundant on DCs in lymphoid tissues. Ovalbumin (OVA) protein, when chemically coupled to monoclonal αDEC-205 antibody, was presented by CD11c+ lymph node DCs, but not by CD11c− cells, to OVA-specific, CD4+ and CD8+ T cells. Receptor-mediated presentation was at least 400 times more efficient than unconjugated OVA and, for MHC class I, the DCs had to express transporter of antigenic peptides (TAP) transporters. When αDEC-205:OVA was injected subcutaneously, OVA protein was identified over a 4–48 h period in DCs, primarily in the lymph nodes draining the injection site. In vivo, the OVA protein was selectively presented by DCs to TCR transgenic CD8+ cells, again at least 400 times more effectively than soluble OVA and in a TAP-dependent fashion. Targeting of αDEC-205:OVA to DCs in the steady state initially induced 4–7 cycles of T cell division, but the T cells were then deleted and the mice became specifically unresponsive to rechallenge with OVA in complete Freund's adjuvant. In contrast, simultaneous delivery of a DC maturation stimulus via CD40, together with αDEC-205:OVA, induced strong immunity. The CD8+ T cells responding in the presence of agonistic αCD40 antibody produced large amounts of interleukin 2 and interferon γ, acquired cytolytic function in vivo, emigrated in large numbers to the lung, and responded vigorously to OVA rechallenge. Therefore, DEC-205 provides an efficient receptor-based mechanism for DCs to process proteins for MHC class I presentation in vivo, leading to tolerance in the steady state and immunity after DC maturation.

IFN-α enhances cross-presentation in human dendritic cells by modulating antigen survival, endocytic routing, and processing

Blood ◽  
2012 ◽  
Vol 119 (6) ◽  
pp. 1407-1417 ◽  
Author(s):  
Francesca Spadaro ◽  
Caterina Lapenta ◽  
Simona Donati ◽  
Laura Abalsamo ◽  
Vincenzo Barnaba ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Tumor Development ◽  
Class I ◽  
Cross Presentation ◽  
The Cross ◽  
Human Dendritic Cells

Abstract Cross-presentation allows antigen-presenting cells to present exogenous antigens to CD8+ T cells, playing an essential role in controlling infections and tumor development. IFN-α induces the rapid differentiation of human mono-cytes into dendritic cells, known as IFN-DCs, highly efficient in mediating cross-presentation, as well as the cross-priming of CD8+ T cells. Here, we have investigated the mechanisms underlying the cross-presentation ability of IFN-DCs by studying the intracellular sorting of soluble ovalbumin and nonstructural-3 protein of hepatitis C virus. Our results demonstrate that, independently from the route and mechanism of antigen entry, IFN-DCs are extraordinarily competent in preserving internalized proteins from early degradation and in routing antigens toward the MHC class-I processing pathway, allowing long-lasting, cross-priming capacity. In IFN-DCs, both early and recycling endosomes function as key compartments for the storage of both antigens and MHC-class I molecules and for proteasome- and transporter-associated with Ag processing–dependent auxiliary cross-presentation pathways. Because IFN-DCs closely resemble human DCs naturally occurring in vivo in response to infections and other danger signals, these findings may have important implications for the design of vaccination strategies in neoplastic or chronic infectious diseases.

scholarly journals Constitutive versus Activation-dependent Cross-Presentation of Immune Complexes by CD8+ and CD8− Dendritic Cells In Vivo

2002 ◽  
Vol 196 (6) ◽  
pp. 817-827 ◽  
Author(s):  
Joke M.M. den Haan ◽  
Michael J. Bevan
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Immune Complexes ◽  
Class I ◽  
Cross Presentation ◽  
Deficient Mice ◽  
Mhc Class I Molecules

Murine splenic dendritic cells (DCs) can be divided into two subsets based on CD8α expression, but the specific role of each subset in stimulation of T cells is largely unknown. An important function of DCs is the ability to take up exogenous antigens and cross-present them in the context of major histocompatibility complex (MHC) class I molecules to CD8+ T cells. We previously demonstrated that, when cell-associated ovalbumin (OVA) is injected into mice, only the CD8+ DC subset cross-presents OVA in the context of MHC class I. In contrast to this selectivity with cell-associated antigen, we show here that both DC subsets isolated from mice injected with OVA/anti-OVA immune complexes (OVA-IC) cross-present OVA to CD8+ T cells. The use of immunoglobulin G Fc receptor (FcγR) common γ-chain–deficient mice revealed that the cross-presentation by CD8− DCs depended on the expression of γ-chain–containing activating FcγRs, whereas cross-presentation by CD8+ DCs was not reduced in γ-chain–deficient mice. These results suggest that although CD8+ DCs constitutively cross-present exogenous antigens in the context of MHC class I molecules, CD8− DCs only do so after activation, such as via ligation of FcγRs. Cross-presentation of immune complexes may play an important role in autoimmune diseases and the therapeutic effect of antitumor antibodies.

Platelet MHC Class I Mediates CD8+ T Cell Suppression During Sepsis

Blood ◽  
2021 ◽  
Author(s):  
Li Guo ◽  
Sikui Shen ◽  
Jesse W Rowley ◽  
Neal D. Tolley ◽  
Wenwen Jia ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Ex Vivo ◽  
Cd8 T Cell ◽  
Class I ◽  
Functional Responses ◽  
Class I Mhc ◽  
Mhc I

Circulating platelets interact with leukocytes to modulate host immune and thrombotic responses. In sepsis, platelet-leukocyte interactions are increased, and have been associated with adverse clinical events, including increased platelet-T cell interactions. Sepsis is associated with reduced CD8+ T cell numbers and functional responses, but whether platelets regulate CD8+ T cell responses during sepsis remains unknown. In our current study, we systemically evaluated platelet antigen internalization and presentation through major histocompatibility complex class I (MHC-I) and their effects on antigen specific CD8+ T cells in sepsis in vivo and ex vivo. We discovered that both human and murine platelets internalize and proteolyze exogenous antigens, generating peptides that are loaded onto MHC-I. The expression of platelet MHC-I, but not platelet MHC-II, is significantly increased in human and murine platelets during sepsis and in human megakaryocytes stimulated with agonists generated systemically during sepsis (e.g., IFN-g and LPS). Upregulation of platelet MHC-I during sepsis increases antigen cross-presentation and interactions with CD8+ T cells in an antigen-specific manner. Using a platelet lineage specific MHC-I deficient mouse strain (B2mf/f--Pf4Cre), we demonstrate that platelet MHC-I regulates antigen-specific CD8+ T cell proliferation in vitro, as well as the number and functional responses of CD8+ T cells in vivo during sepsis. Loss of platelet MHC-I reduced sepsis-associated mortality in mice in an antigen specific setting. These data identify a new mechanism by which platelets, through MHC-I, process and cross-present antigens, engage antigen specific CD8+ T cells, and regulate CD8+ T cell number, functional responses, and outcomes during sepsis.

scholarly journals Mesothelin-specific CD8+ T Cell Responses Provide Evidence of In Vivo Cross-Priming by Antigen-Presenting Cells in Vaccinated Pancreatic Cancer Patients

2004 ◽  
Vol 200 (3) ◽  
pp. 297-306 ◽  
Author(s):  
Amy Morck Thomas ◽  
Lynn M. Santarsiero ◽  
Eric R. Lutz ◽  
Todd D. Armstrong ◽  
Yi-Cheng Chen ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cross Presentation ◽  
Cell Responses ◽  
Antigen Presenting

Tumor-specific CD8+ T cells can potentially be activated by two distinct mechanisms of major histocompatibility complex class I–restricted antigen presentation as follows: direct presentation by tumor cells themselves or indirect presentation by professional antigen-presenting cells (APCs). However, controversy still exists as to whether indirect presentation (the cross-priming mechanism) can contribute to effective in vivo priming of tumor-specific CD8+ T cells that are capable of eradicating cancer in patients. A clinical trial of vaccination with granulocyte macrophage–colony stimulating factor–transduced pancreatic cancer lines was designed to test whether cross-presentation by locally recruited APCs can activate pancreatic tumor-specific CD8+ T cells. Previously, we reported postvaccination delayed-type hypersensitivity (DTH) responses to autologous tumor in 3 out of 14 treated patients. Mesothelin is an antigen demonstrated previously by gene expression profiling to be up-regulated in most pancreatic cancers. We report here the consistent induction of CD8+ T cell responses to multiple HLA-A2, A3, and A24-restricted mesothelin epitopes exclusively in the three patients with vaccine-induced DTH responses. Importantly, neither of the vaccinating pancreatic cancer cell lines expressed HLA-A2, A3, or A24. These results provide the first direct evidence that CD8 T cell responses can be generated via cross-presentation by an immunotherapy approach designed to recruit APCs to the vaccination site.

scholarly journals Conditional silencing of H-2Dbclass I molecule expression on dendritic cells modulates the protective and pathogenic kinetics of virus-antigen specific CD8 T cell responses during Theiler’s Virus infection

2019 ◽  
Author(s):  
Zachariah P. Tritz ◽  
Robin C. Orozco ◽  
Courtney S. Malo ◽  
Lila T Yokanovich ◽  
Katayoun Ayasoufi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antigen Presentation ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Class I ◽  
Viral Control ◽  
Cell Responses

ABSTRACTTheiler’s murine encephalomyelitis virus (TMEV) infection of the central nervous system is rapidly cleared in C57BL/6 mice by an anti-viral CD8 T cell response restricted by the MHC class I molecule, H-2Db. While the CD8 T cell response against neurotropic viruses is well characterized, the identity and function of the antigen presenting cell(s) involved in this process is(are) less well defined. To address this gap in knowledge, we developed a novel C57BL/6 H-2Dbconditional knockout mouse that expresses an H-2Dbtransgene in which the transmembrane domain locus is flanked by LoxP sites. We crossed these H-2DbLoxP mice with MHC class I-deficient mice expressing Cre-recombinase under either the CD11c or LysM promoter in order to silence H-2Dbrestricted antigen presentation predominantly in dendritic cells or macrophages, respectively. Upon challenge with intracranial TMEV infection, we observe that CD11c+ APCs are critical for early priming of CD8 T cells against the immunodominant TMEV peptide VP2121-130 presented in the context of the H-2Dbmolecule. This stands in stark contrast to later time points post TMEV infection where CD11c+ APCs appear dispensable for the activation of antigen-specific T cells; the functionality of these late-arising antiviral CD8 T cells is reflected in the restoration of viral control at later time points. These late-arising CD8 T cells also retain their capacity to induce blood-brain barrier disruption. In contrast, when H-2Dbrestricted antigen presentation was selectively silenced in LysM+ APCs there was no overt impact on the priming of Db:VP2121-130 epitope-specific CD8 T cells, although a modest reduction in immune cell entry into the CNS was observed. This work establishes a model system which enables critical dissection of MHC class I restricted antigen presentation to T cells, revealing cell specific and temporal features involved in the generation of antiviral CD8 T cell responses. Employing this novel system, we established CD11c+ cells as a pivotal driver of acute, but not later-arising, antiviral CD8 T cell responses against the TMEV immunodominant epitope VP2121-130, with functional implications both for T cell-mediated viral control and immunopathology.

Identification of Novel MHC Class I and Class II Epitopes of WT1 Using a Peptide Library Screen.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2764-2764 ◽  
Author(s):  
Katayoun Rezvani ◽  
Stephan Mielke ◽  
Yasemin Kilical ◽  
Matthias Grube ◽  
Hiroshi Fujiwara ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Class Ii ◽  
Peptide Library ◽  
Class I ◽  
Cell Responses

Abstract Although several HLA-A*0201-restricted immunodominant peptides from the leukemia-restricted protein WT-1 are characterized, T cell responses to peptide sequences binding to other common class I and II epitopes of WT-1 remain almost completely unexplored. A more comprehensive definition of the WT-1 antigen would extend peptide antigen vaccines to individuals lacking HLA-A*0201 and *2402 and improve vaccine potency by recruiting both CD4+ and CD8+ T cell responses. Here we used a WT1 peptide library to identify WT-1 peptide sequences inducing CD4+ and CD8+ T cell responses in normal individuals and patients with AML and other myeloid leukemias. Six cases were studied. The library consisted of 110 15mer peptides overlapping by 11aa covering the entire WT-1 protein in 21 pools. Monocytes were isolated by plastic adherence and pulsed with peptide pools for 3 hours. Autologous CD8+ and CD4+ T cells were then added. Pools of peptides were prepared in such a way that each peptide was represented in two different peptide pools, allowing the identification of the respective peptide by responses in the two corresponding pools. Cells were harvested for RNA extraction and reverse transcription. Real time PCR (RQ-PCR) was used to identify peptide-specific induction of IFN-γ and IL-2 in CD8+ and CD4+ T cells. The SYFPEITHI binding motif software was then used to predict the probable HLA restriction for the candidate epitopes. To confirm candidate peptide immunogenecity and HLA restriction, selected peptides were synthesized and tested individually. In addition to the known HLA-A*0201 peptides WT37, WT126, WT187 and WT235 we identified 20 new MHC class I and II epitopes of WT1. Four were restricted by more than one HLA allele, demonstrating the promiscuity of epitope binding. One epitope (VPGVAPTLV) was restricted to HLA-A*0201 and HLA-B*5101. One epitope (SGQFTGTAGACRYGP) was restricted by a class I HLA allele, namely HLA-*6801 and a class II HLA allele, DR*1501. Two epitopes (YGPFGPPPPSQASGQ and QKKFARSDELVRHHN) were restricted by multiple MHC class II alleles. The proliferative response of CD4+ and CD8+ T cells to candidate peptides was confirmed using CFSE labeling. We now plan to characterize the antileukemic effects of CD4+ and CD8+ T cells induced by these peptides with a view to designing broad-spectrum vaccines inducing leukemia-reactive T cells across a wide range of HLA types.

scholarly journals MHC Class I-Restricted TCR-Transgenic CD4+ T Cells Against STEAP1 Mediate Local Tumor Control of Ewing Sarcoma In Vivo

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1581 ◽  
Author(s):  
Sebastian J. Schober ◽  
Melanie Thiede ◽  
Hendrik Gassmann ◽  
Carolin Prexler ◽  
Busheng Xue ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Ewing Sarcoma ◽  
Local Tumor Control ◽  
Class I ◽  
Tumor Control ◽  
Local Tumor

In this study we report the functional comparison of T cell receptor (TCR)-engineered major histocompatibility complex (MHC) class I-restricted CD4+ versus CD8+ T cells targeting a peptide from six transmembrane epithelial antigen of the prostate 1 (STEAP1) in the context of HLA-A*02:01. STEAP1 is a tumor-associated antigen, which is overexpressed in many cancers, including Ewing sarcoma (EwS). Based on previous observations, we postulated strong antitumor potential of tumor-redirected CD4+ T cells transduced with an HLA class I-restricted TCR against a STEAP1-derived peptide. We compared CD4+ T cell populations to their CD8+ counterparts in vitro using impedance-based xCELLigence and cytokine/granzyme release assays. We further compared antitumor activity of STEAP130-TCR transgenic (tg) CD4+ versus CD8+ T cells in tumor-bearing xenografted Rag2−/−γc−/− mice. TCR tgCD4+ T cells showed increased cytotoxic features over time with similar functional avidity compared to tgCD8+ cells after 5–6 weeks of culture. In vivo, local tumor control was equal. Assessing metastatic organotropism of intraveniously (i.v.) injected tumors, only tgCD8+ cells were associated with reduced metastases. In this analysis, EwS-redirected tgCD4+ T cells contribute to local tumor control, but fail to control metastatic outgrowth in a model of xenografted EwS.

scholarly journals Stable Antigen Is Most Effective for Eliciting CD8+T-Cell Responses after DNA Vaccination and Infection with Recombinant Vaccinia VirusIn Vivo

2012 ◽  
Vol 86 (18) ◽  
pp. 9782-9793 ◽  
Author(s):  
Christopher Schliehe ◽  
Annegret Bitzer ◽  
Maries van den Broek ◽  
Marcus Groettrup
Keyword(s):  
T Cell ◽  
Mhc Class I ◽  
T Cell Responses ◽  
Dna Vaccination ◽  
Class I ◽  
Antigenic Peptides ◽  
Recombinant Vaccinia ◽  
Cross Presentation ◽  
Cell Responses

The induction of strong CD8+T-cell responses against infectious diseases and cancer has remained a major challenge. Depending on the source of antigen and the infectious agent, priming of CD8+T cells requires direct and/or cross-presentation of antigenic peptides on major histocompatibility complex (MHC) class I molecules by professional antigen-presenting cells (APCs). However, both pathways show distinct preferences concerning antigen stability. Whereas direct presentation was shown to efficiently present peptides derived from rapidly degraded proteins, cross-presentation is dependent on long-lived antigen species. In this report, we analyzed the role of antigen stability on DNA vaccination and recombinant vaccinia virus (VV) infection using altered versions of the same antigen. The long-lived nucleoprotein (NP) of lymphocytic choriomeningitis virus (LCMV) can be targeted for degradation by N-terminal fusion to ubiquitin or, as we show here, to the ubiquitin-like modifier FAT10. Direct presentation by cells either transfected with NP-encoding plasmids or infected with recombinant VVin vitrowas enhanced in the presence of short-lived antigens.In vivo, however, the highest induction of NP-specific CD8+T-cell responses was achieved in the presence of long-lived NP. Our experiments provide evidence that targeting antigens for proteasomal degradation does not improve the immunogenicity of DNA vaccines and recombinant VVs. Rather, it is the long-lived antigen that is superior for the efficient activation of MHC class I-restricted immune responsesin vivo. Hence, our results suggest a dominant role for antigen cross-priming in DNA vaccination and recombinant VV infection.

scholarly journals NOD2 and TLR2 Signal via TBK1 and PI31 to Direct Cross-presentation and CD8 T Cell Responses

2019 ◽  
Author(s):  
Daniele Corridoni ◽  
Seiji Shiraishi ◽  
Thomas Chapman ◽  
Tessa Steevels ◽  
Daniele Muraro ◽  
...  
Keyword(s):  
T Cell ◽  
Mhc Class I ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
Class I ◽  
Cross Presentation ◽  
Cell Responses ◽  
Direct Cross

AbstractNOD2 and TLR2 recognize components of bacterial cell wall peptidoglycan and direct defense against enteric pathogens. CD8+ T cells are important for immunity to such pathogens but how NOD2 and TLR2 induce antigen specific CD8+ T cell responses is unknown. Here, we define how these pattern recognition receptors (PRRs) signal in primary dendritic cells (DCs) to influence MHC class I antigen presentation. We show NOD2 and TLR2 phosphorylate PI31 via TBK1 following activation in DCs. PI31 interacts with TBK1 and Sec16A at endoplasmic reticulum exit sites (ERES), which positively regulates MHC class I peptide loading and immunoproteasome stability. Following NOD2 and TLR2 stimulation, depletion of PI31 or inhibition of TBK1 activity in vivo impairs DC cross-presentation and CD8+ T cell activation. DCs from Crohn’s patients expressing NOD2 polymorphisms show dysregulated cross-presentation and CD8+ T cell responses. Our findings reveal unidentified mechanisms that underlie CD8+ T cell responses to bacteria in health and in Crohn’s.

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