GO:0042590 antigen processing and presentation of exogenous peptide antigen via MHC class I: Cross-Presentation Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0042590 describes cross-presentation, the process by which an antigen-presenting cell displays an exogenous peptide on MHC class I to CD8+ T cells.
• Exogenous antigens can be processed in the cytosol or in endosomal compartments before loading onto MHC class I.
• Cross-presentation is essential for immunity to viruses that do not infect dendritic cells and for antitumor T cell priming.
• Soluble and particulate antigens are handled by distinct intracellular routes that can be studied with model antigens.
• Viruses encode immune-evasion proteins that interfere with MHC class I antigen presentation, making this pathway a host-pathogen interface.
• CRISPR knockout, knock-in, and overexpression models enable causal dissection of genes controlling cross-presentation.
Description
Antigen processing and presentation of exogenous peptide antigen via MHC class I, defined by the Gene Ontology term GO:0042590, is the process in which an antigen-presenting cell expresses a peptide antigen of exogenous origin on its cell surface in association with an MHC class I protein complex. This pathway is widely known as cross-presentation and allows CD8+ T cell responses to antigens that are not synthesized within the presenting cell itself. The QuickGO definition specifies that the peptide antigen is typically, but not always, processed from a whole protein, and that class I here refers to classical class I molecules. Because cross-presentation bridges the exogenous and endogenous antigen presentation routes, it is central to immunity against viruses that fail to productively infect dendritic cells and against tumors. Researchers study GO:0042590 to understand how antigen routing, peptide trimming, and MHC class I loading are coordinated in endosomal and cytosolic compartments. The pathway is also a target of viral immune evasion, as several viruses encode proteins that block MHC class I peptide presentation. Experimental systems using synthetic long peptides, soluble antigens, and phage particles have helped define the intracellular transport routes that support cross-presentation. Consequently, GO:0042590 is a high-value ontology term for immunologists, virologists, and cancer biologists seeking to manipulate CD8+ T cell priming.
antigen processing and presentation of exogenous peptide antigen via MHC class I At A Glance
| GO ID | GO:0042590 |
|---|---|
| GO term | antigen processing and presentation of exogenous peptide antigen via MHC class I |
| Ontology | biological_process |
| Synonym | cross-presentation; cross-priming; exogenous antigen via MHC class I |
| Major function | Presentation of exogenous peptides on classical MHC class I to CD8+ T cells |
| Cellular context | Antigen-presenting cells including dendritic cells and macrophages |
| Antigen source | Exogenous proteins, synthetic long peptides, or particulate antigens |
| Key compartments | Endosomes, cytosol, endoplasmic reticulum, and plasma membrane |
| Related process | MHC class I antigen processing and presentation (direct presentation) |
What Is GO:0042590?
GO:0042590 is a biological process term describing how an antigen-presenting cell takes up exogenous material, processes it into peptides, and presents those peptides on the cell surface in complex with classical MHC class I molecules. In contrast to direct presentation, where MHC class I molecules display peptides derived from proteins synthesized inside the cell, cross-presentation uses peptides derived from external antigens. The term includes both cytosolic and vacuolar processing routes and is synonymous with cross-presentation and cross-priming.
Why Is antigen processing and presentation of exogenous peptide antigen via MHC class I Important in Cell Biology?
GO:0042590 is important because it explains how the immune system detects threats that are not synthesized inside dendritic cells, including viral proteins and tumor antigens. Without cross-presentation, CD8+ T cell priming against many viruses and cancers would be severely impaired. The pathway also determines the outcome of vaccination with exogenous antigens and synthetic long peptides. Because viruses have evolved proteins that interfere with MHC class I presentation, understanding GO:0042590 informs antiviral immunity and immune-evasion research. In addition, neonatal dendritic cells show deficient cross-presentation of soluble antigen, linking this pathway to age-dependent immune responses.
• Enables CD8+ T cell priming against viruses that do not infect antigen-presenting cells.
• Supports antitumor immunity by presenting exogenous tumor antigens on MHC class I.
• Explains how synthetic long peptides and soluble antigens are cross-presented.
• Defines intracellular transport routes for MHC class I and their relevance to cross-presentation.
• Provides a mechanistic basis for viral immune evasion targeting MHC class I presentation.
• Relevant to vaccine design using exogenous protein or peptide antigens.
• Links antigen routing in endosomes and the endoplasmic reticulum to T cell activation.
• Helps interpret age-related differences in dendritic cell function.
• Guides CRISPR screens for genes controlling cross-presentation.
• Connects to immune privilege and autoimmune contexts where MHC class I presentation is altered.
What Happens During antigen processing and presentation of exogenous peptide antigen via MHC class I?
Antigen uptake and endosomal routing
In simple terms: The cell first takes in material from outside and sends it into endosomal compartments.
Cross-presentation begins when an antigen-presenting cell internalizes exogenous antigen, such as a soluble protein, synthetic long peptide, or particulate antigen. Internalized material is delivered to endosomal compartments, where it can be processed or routed further. Studies with synthetic 102-mer malaria vaccine polypeptide show that exogenous polypeptides can be presented in an MHC class I-restricted manner. Phage particle antigen is cross-presented in MHC class II and endoplasmic reticulum marker-positive compartments, indicating that endosomal routing intersects with ER-like compartments.
Cytosolic processing route
In simple terms: Some antigen escapes into the cytosol, where it is chopped into peptides like internally made proteins.
In the cytosolic route, exogenous antigen is transported from endosomes into the cytosol, where it enters the classical MHC class I processing machinery. This route allows exogenous proteins to be degraded by the proteasome and the resulting peptides to be loaded onto MHC class I. Intracellular transport routes for MHC class I are therefore central to antigen cross-presentation. This pathway explains how exogenous antigens access the same peptide pool as endogenous antigens.
Vacuolar processing route
In simple terms: Alternatively, peptides can be made and loaded onto MHC class I directly inside endosomal compartments.
In the vacuolar route, exogenous antigen is processed within endosomal compartments and loaded onto MHC class I locally. Cross-presentation of phage particle antigen occurs in MHC class II and endoplasmic reticulum marker-positive compartments, supporting the existence of specialized loading compartments. This route can operate independently of the classical cytosolic pathway and may favor particulate antigens. The coexistence of cytosolic and vacuolar routes provides flexibility for different antigen forms.
Peptide loading and surface presentation
In simple terms: The peptide is placed onto MHC class I and carried to the cell surface for T cells to see.
After processing, exogenous peptides are loaded onto classical MHC class I molecules and the complex is transported to the plasma membrane. Surface presentation of the exogenous peptide-MHC class I complex allows recognition by CD8+ T cells. Priming of T cells by exogenous antigen cross-presented on MHC class I molecules is the functional outcome of this pathway. Viral immune-evasion proteins can interfere with steps in this presentation route, highlighting its importance in antiviral defense.
Regulation by antigen form and cell type
In simple terms: Different antigens and different cells change how efficiently this process works.
Cross-presentation efficiency depends on antigen form, with soluble and particulate antigens handled differently. Murine neonatal dendritic cells are deficient in MHC class I cross-presentation of soluble antigen, showing that developmental stage affects this pathway. Human cytomegalovirus pp65 shows nucleocytoplasmic shuttling and CRM1-dependent MHC class I peptide presentation, linking nuclear export to presentation. These findings indicate that GO:0042590 is regulated at the level of antigen routing, cell type, and viral interference.
Key Genes Involved in GO:0042590 antigen processing and presentation of exogenous peptide antigen via MHC class I
The genes and proteins below are experimentally implicated in antigen processing and presentation of exogenous peptide antigen via MHC class I (GO:0042590) based on the verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| HLA-A | Classical MHC class I heavy chain presenting exogenous peptides | Core molecule for cross-presentation assays |
| HLA-B | Classical MHC class I heavy chain presenting exogenous peptides | Determines peptide repertoire in cross-presentation |
| B2M | Beta-2-microglobulin, essential MHC class I light chain | Knockout abolishes surface MHC class I presentation |
| TAP1 | Peptide transporter for MHC class I loading | Links cytosolic processing to cross-presentation |
| TAP2 | Peptide transporter for MHC class I loading | Required for cytosolic route of cross-presentation |
| PSMB8 | Immunoproteasome subunit for peptide generation | Affects peptide supply for cross-presentation |
| PSMB9 | Immunoproteasome subunit for peptide generation | Modulates exogenous peptide processing |
| CANX | Calnexin, MHC class I assembly chaperone | Supports peptide loading complex function |
| CALR | Calreticulin, MHC class I assembly chaperone | Supports peptide loading complex function |
| PDIA3 | ERp57, oxidoreductase in peptide loading complex | Facilitates MHC class I peptide loading |
| TAPBP | Tapasin, bridges TAP and MHC class I | Central to peptide loading for cross-presentation |
| SEC61A1 | ER translocon component implicated in antigen transport | Potential route for exogenous antigen into ER |
| RAB7A | Late endosomal trafficking regulator | Controls endosomal routing of exogenous antigen |
| LAMP1 | Lysosomal-associated membrane protein 1 | Marks endosomal compartments in cross-presentation |
| CTSB | Cathepsin B, endosomal protease | Processes exogenous antigen in vacuolar route |
| CTSS | Cathepsin S, endosomal protease | Contributes to antigen processing for presentation |
| XPO1 | CRM1 nuclear export receptor | Mediates CRM1-dependent MHC class I peptide presentation of pp65 |
How Is antigen processing and presentation of exogenous peptide antigen via MHC class I Regulated?
GO:0042590 is regulated at multiple levels, including antigen uptake, endosomal routing, cytosolic export, and peptide loading onto MHC class I. The route taken by exogenous antigen determines whether processing occurs in the cytosol or in endosomal compartments. Developmental state influences cross-presentation, as murine neonatal dendritic cells are deficient in MHC class I cross-presentation of soluble antigen. Viral proteins can actively interfere with MHC class I antigen presentation, providing a pathogen-driven layer of regulation. Human cytomegalovirus pp65 nucleocytoplasmic shuttling and CRM1-dependent presentation further show that nuclear export can regulate peptide presentation.
antigen processing and presentation of exogenous peptide antigen via MHC class I and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| HLA-A | Antitumor and antiviral CD8+ T cell immunity | HLA-A knock-in reporter cells for cross-presentation assays |
| B2M | Loss of MHC class I presentation in tumors | B2M knockout dendritic cell line |
| TAP1 | Impaired peptide transport and cross-presentation | TAP1 knockout cells with exogenous antigen challenge |
| XPO1 | Viral immune evasion by HCMV pp65 | XPO1 point-mutation or knockout cells expressing pp65 |
| LAMP1 | Endosomal routing in cross-presentation | LAMP1-tagged knock-in for imaging endosomal compartments |
Cancer immunity and immunotherapy
Cross-presentation of exogenous tumor antigens on MHC class I is required for CD8+ T cell priming against tumors. Defects in this pathway can limit antitumor immunity and reduce responses to antigen-based immunotherapies. Understanding GO:0042590 therefore supports the design of vaccines and cell therapies that rely on exogenous antigen delivery.
Viral infection and immune evasion
Viruses encode proteins that interfere with MHC class I antigen presentation, including steps relevant to cross-presentation. Human cytomegalovirus pp65 shows nucleocytoplasmic shuttling and CRM1-dependent MHC class I peptide presentation, illustrating how viral proteins intersect with this pathway. These mechanisms help explain viral persistence and inform antiviral strategies.
Neonatal and age-related immunity
Murine neonatal dendritic cells are deficient in MHC class I cross-presentation of soluble antigen, linking GO:0042590 to age-dependent immune responses. This deficiency may contribute to impaired CD8+ T cell priming in early life. Studying this pathway can inform vaccine strategies for neonates.
Autoimmunity and immune privilege
MHC class I presentation is relevant to immune privilege and its collapse in alopecia areata, where hair follicle immune privilege is lost. Although GO:0042590 specifically concerns exogenous antigen cross-presentation, altered MHC class I presentation in tissues can contribute to autoimmune attack. This connection highlights the broader importance of MHC class I antigen handling in disease.
From antigen processing and presentation of exogenous peptide antigen via MHC class I-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene required for cross-presentation? | CRISPR knockout in dendritic cell line or primary cells |
| Does a specific residue control antigen routing? | Point-mutation knock-in of the candidate gene |
| Where does the antigen encounter MHC class I? | Tagged knock-in of MHC class I or endosomal markers |
| Does overexpression enhance cross-presentation? | Overexpression of candidate gene in antigen-presenting cells |
| Which genes regulate exogenous peptide presentation? | CRISPR library screening with antigen-specific T cell readout |
| How does viral protein shuttling affect presentation? | Knock-in of viral protein such as HCMV pp65 with CRM1 perturbation |
How to Study the antigen processing and presentation of exogenous peptide antigen via MHC class I Process
| Method | What It Measures | Typical Application |
|---|---|---|
| T cell activation assay | CD8+ T cell priming by cross-presented antigen | Functional readout of GO:0042590 |
| Synthetic long peptide presentation | MHC class I-restricted exogenous presentation | Vaccine antigen testing |
| Soluble antigen cross-presentation | Efficiency of soluble antigen presentation | Neonatal versus adult dendritic cell comparison |
| Phage particle antigen tracking | Intracellular compartments for cross-presentation | Endosomal and ER marker colocalization |
| Immunopeptidomics | MHC class I peptide repertoire | Identification of exogenous peptides |
| CRISPR knockout | Requirement of a gene for cross-presentation | Causal gene discovery |
| CRISPR library screening | Genome-wide regulators of presentation | Pathway discovery |
| Viral protein expression | Immune evasion of MHC class I presentation | HCMV pp65 shuttling studies |
Antigen-specific T cell activation assays
Cross-presentation is commonly measured by co-culturing antigen-pulsed antigen-presenting cells with antigen-specific CD8+ T cells and detecting T cell activation. Synthetic long peptides and soluble antigens are used to probe exogenous presentation. These assays directly report the functional output of GO:0042590.
Imaging of intracellular antigen routes
Fluorescently labeled antigens and organelle markers allow tracking of exogenous antigen through endosomal and ER-like compartments. Phage particle antigen cross-presentation in MHC class II and endoplasmic reticulum marker-positive compartments was defined using such approaches. Imaging can reveal whether antigen follows cytosolic or vacuolar routes.
Proteomics and immunopeptidomics
Mass spectrometry of MHC class I-bound peptides can identify exogenous peptides presented on the cell surface. Immunopeptidomics helps define the peptide repertoire generated through cross-presentation. This approach complements functional T cell assays.
Genetic perturbation and CRISPR screening
CRISPR knockout, point mutation, knock-in, and overexpression models enable causal testing of genes in GO:0042590. Library screening can identify regulators of exogenous peptide presentation. Viral proteins such as HCMV pp65 can be expressed or mutated to study immune evasion.
How CRISPR Can Be Used to Study GO:0042590 antigen processing and presentation of exogenous peptide antigen via MHC class I
Knockout
CRISPR knockout of candidate genes such as B2M, TAP1, or RAB7A can test their requirement for antigen processing and presentation of exogenous peptide antigen via MHC class I. Loss of surface MHC class I presentation is a common readout. Knockout models help distinguish essential from redundant factors in cross-presentation.
Point Mutation
Point-mutation knock-in can dissect specific residues controlling antigen routing, peptide loading, or viral protein shuttling. For example, mutations affecting CRM1-dependent nuclear export of HCMV pp65 can be modeled to study MHC class I peptide presentation. Such models provide mechanistic resolution beyond simple knockout.
Knock-in
Tagged knock-in of MHC class I components or endosomal markers enables visualization of antigen handling in live cells. Knock-in of viral proteins such as pp65 allows study of immune evasion in a physiological context. These models support imaging and proteomic workflows for GO:0042590.
Overexpression
Overexpression of candidate genes can test whether increased levels enhance cross-presentation of exogenous antigen. Overexpression of antigen-processing components may boost MHC class I peptide presentation. This approach is useful for gain-of-function studies in antigen-presenting cells.
How EDITGENE Supports antigen processing and presentation of exogenous peptide antigen via MHC class I Research
Researchers studying antigen processing and presentation of exogenous peptide antigen via MHC class I-related genes often need to determine whether a candidate gene is causally involved in antigen routing, peptide loading, or T cell priming. EDITGENE provides CRISPR-based cell models and screening services to test these hypotheses with publication-ready rigor.
Contact EDITGENE today to design your custom CRISPR model for antigen processing and presentation of exogenous peptide antigen via MHC class I research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| IFI30 Knockout HEK293 Cell Line | EDJ-KQ7046 | Human | 10437 | Details Get a Quote |
| MPEG1 Knockout HEK293 Cell Line | EDJ-KQ8466 | Human | 219972 | Details Get a Quote |
| CLEC4A Knockout HEK293 Cell Line | EDJ-KQ10835 | Human | 50856 | Details Get a Quote |
| MFSD6 Knockout HEK293 Cell Line | EDJ-KQ12224 | Human | 54842 | Details Get a Quote |
| HLA-A Knockout HEK293 Cell Line | EDJ-KQ13752 | Human | 3105 | Details Get a Quote |
| MFSD6 Knockout HeLa Cell Line | EDJ-KQ17938 | Human | 54842 | Details Get a Quote |
| MFSD6 Knockout A-549 Cell Line | EDJ-KQ40980 | Human | 54842 | Details Get a Quote |
| MFSD6 Knockout HCT 116 Cell Line | EDJ-KQ40981 | Human | 54842 | Details Get a Quote |
| IFI30 Knockout HCT 116 Cell Line | EDJ-KQ30449 | Human | 10437 | Details Get a Quote |
| IFI30 Knockout A-549 Cell Line | EDJ-KQ31821 | Human | 10437 | Details Get a Quote |
| IFI30 Knockout HeLa Cell Line | EDJ-KQ31823 | Human | 10437 | Details Get a Quote |
| CLEC4A Knockout HCT 116 Cell Line | EDJ-KQ38487 | Human | 50856 | Details Get a Quote |
| HLA-A Knockout HeLa Cell Line | EDJ-KQ42265 | Human | 3105 | Details Get a Quote |
| HLA-A Knockout A-549 Cell Line | EDJ-KQ43522 | Human | 3105 | Details Get a Quote |
| HLA-A Knockout HCT 116 Cell Line | EDJ-KQ43523 | Human | 3105 | Details Get a Quote |
Displaying Records 1 To 15 Of 21 Records
Frequently Asked Questions About antigen processing and presentation of exogenous peptide antigen via MHC class I
What is GO:0042590?
GO:0042590 is the Gene Ontology term for antigen processing and presentation of exogenous peptide antigen via MHC class I, also known as cross-presentation.
What is cross-presentation?
Cross-presentation is the process by which exogenous antigens are presented on MHC class I molecules to CD8+ T cells.
What genes are involved in antigen processing and presentation of exogenous peptide antigen via MHC class I?
Genes include HLA-A, HLA-B, B2M, TAP1, TAP2, PSMB8, PSMB9, CANX, CALR, PDIA3, TAPBP, RAB7A, LAMP1, CTSB, CTSS, and XPO1.
How is exogenous antigen processed for MHC class I presentation?
Exogenous antigen can be processed in the cytosol or in endosomal compartments before loading onto MHC class I.
Why is cross-presentation important for antiviral immunity?
It allows CD8+ T cell priming against viruses that do not infect antigen-presenting cells, and viruses encode proteins that interfere with MHC class I presentation.
Can soluble antigens be cross-presented?
Yes, soluble antigens can be cross-presented, although efficiency varies with cell type such as neonatal dendritic cells.
What experimental models study GO:0042590?
Models include synthetic long peptide presentation, soluble antigen assays, phage particle antigen tracking, and CRISPR knockout or knock-in cells.
How do viruses evade MHC class I presentation?
Viruses encode immune-evasion proteins that interfere with MHC class I antigen presentation, including HCMV pp65 with CRM1-dependent shuttling.
What is the role of TAP1 in cross-presentation?
TAP1 transports peptides for MHC class I loading and is relevant to the cytosolic route of cross-presentation.
How can CRISPR help study cross-presentation?
CRISPR knockout, point mutation, knock-in, overexpression, and library screening can causally test genes in GO:0042590.
Conclusion
GO:0042590 defines the cross-presentation pathway that allows exogenous antigens to be displayed on classical MHC class I molecules and recognized by CD8+ T cells. This process is central to antiviral and antitumor immunity, is targeted by viral immune-evasion proteins, and varies with antigen form and cell type. CRISPR-based models and functional T cell assays provide robust tools to dissect the genes and routes controlling this pathway.
References
- 1. Bertolini M et al.. 2020. Hair follicle immune privilege and its collapse in alopecia areata.. Exp Dermatol 29(8):703-725 PMID: 32682334
- 2. Prato S et al.. 2005. MHC class I-restricted exogenous presentation of a synthetic 102-mer malaria vaccine polypeptide.. Eur J Immunol 35(3):681-9 PMID: 15688345
- 3. Adiko AC et al.. 2015. Intracellular Transport Routes for MHC I and Their Relevance for Antigen Cross-Presentation.. Front Immunol 6:335 PMID: 26191062
- 4. van de Weijer ML et al.. 2015. Viral immune evasion: Lessons in MHC class I antigen presentation.. Semin Immunol 27(2):125-37 PMID: 25887630
- 5. Kollmann TR et al.. 2004. Deficient MHC class I cross-presentation of soluble antigen by murine neonatal dendritic cells.. Blood 103(11):4240-2 PMID: 14982880
- 6. Shen L et al.. 2006. Priming of T cells by exogenous antigen cross-presented on MHC class I molecules.. Curr Opin Immunol 18(1):85-91 PMID: 16326087
- 7. Wan Y et al.. 2005. Cross-presentation of phage particle antigen in MHC class II and endoplasmic reticulum marker-positive compartments.. Eur J Immunol 35(7):2041-50 PMID: 15940671
- 8. Frankenberg N et al.. 2012. Nucleocytoplasmic shuttling and CRM1-dependent MHC class I peptide presentation of human cytomegalovirus pp65.. Med Microbiol Immunol 201(4):567-79 PMID: 22965172
