GO:0002505 antigen processing and presentation of polysaccharide antigen via MHC class II: Immune Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0002505 describes the biological process in which an antigen-presenting cell expresses a polysaccharide antigen on its surface in association with an MHC class II protein complex.
• Zwitterionic capsular polysaccharides are the best-characterized MHC class II-dependent polysaccharide antigens, distinguishing them from conventional protein antigens.
• The polysaccharide portion of glycoconjugate vaccines, such as the pneumococcal CRM197 conjugate, co-localizes with MHC class II on the antigen-presenting cell surface.
• MHC class II immunopeptide presentation is accompanied by profound N-glycan remodelling, which may influence polysaccharide antigen handling.
• Enteric glial cells can express MHC class II and regulate lymphocyte activation via autophagy-mediated mechanisms, expanding the known cell types capable of this process [3,5].
• Key experimental models include GM-CSF bone marrow cultures, which contain heterogeneous CD11c+ MHCII+ macrophages and dendritic cells suitable for studying polysaccharide antigen presentation.
Description
Antigen processing and presentation of polysaccharide antigen via MHC class II (GO:0002505) is a specialized biological process in which an antigen-presenting cell expresses a polysaccharide antigen on its cell surface in association with an MHC class II protein complex. This pathway is distinct from conventional protein antigen presentation because polysaccharides are not processed into peptides; instead, zwitterionic capsular polysaccharides can directly associate with MHC class II molecules and be recognized by T cells. The process is critical for understanding immunity to encapsulated bacteria and for optimizing glycoconjugate vaccine design. Researchers studying this term investigate how polysaccharide antigens are internalized, trafficked, and displayed on the cell surface, as well as which cell types and molecular regulators are involved [1,3,4,5,6,8]. The pathway has been studied in dendritic cells, macrophages, enteric glial cells, and other antigen-presenting cells, with evidence that autophagy, class I myosin Myo1e, and protein kinase C delta modulate MHC class II antigen presentation [3,4,5,6]. Because polysaccharide antigens are T-independent in many contexts, their MHC class II-dependent presentation represents a unique bridge between innate and adaptive immunity. This article synthesizes the current understanding of GO:0002505, its molecular players, disease relevance, and experimental approaches for CRISPR-based interrogation.
antigen processing and presentation of polysaccharide antigen via MHC class II At A Glance
| GO ID | GO:0002505 |
|---|---|
| GO term | antigen processing and presentation of polysaccharide antigen via MHC class II |
| Ontology | biological_process |
| Synonym | polysaccharide antigen processing and presentation via MHC class II |
| Definition | The process in which an antigen-presenting cell expresses a polysaccharide antigen on its cell surface in association with an MHC class II protein complex. |
| Major function | Display of polysaccharide antigens on MHC class II for T cell recognition |
| Key cell types | Dendritic cells, macrophages, enteric glial cells [1,3,5] |
| Example antigen | Zwitterionic capsular polysaccharides; pneumococcal CRM197 conjugate polysaccharide [7,8] |
| Related process | MHC class II antigen presentation; autophagy-mediated MHC-II expression |
What Is GO:0002505?
GO:0002505 is defined as the process in which an antigen-presenting cell expresses a polysaccharide antigen on its cell surface in association with an MHC class II protein complex. In simpler terms, it is the cellular pathway by which sugar-based antigens from pathogens or vaccines are displayed on the surface of immune cells using MHC class II molecules, enabling recognition by T cells. This process is distinct from classical peptide antigen presentation because the antigen is a polysaccharide rather than a protein fragment.
Why Is antigen processing and presentation of polysaccharide antigen via MHC class II Important in Cell Biology?
GO:0002505 is important because it defines a non-classical antigen presentation pathway that is essential for immune responses to encapsulated bacteria and for the efficacy of glycoconjugate vaccines [7,8]. Understanding this process can inform vaccine design, explain T cell activation by polysaccharide antigens, and reveal how different antigen-presenting cell types contribute to immunity [1,3,5]. It also has implications for autoimmunity and inflammation, as dysregulated MHC class II presentation of polysaccharides may contribute to aberrant T cell responses [3,5].
• Provides a mechanism for T cell recognition of polysaccharide antigens, which are otherwise T-independent.
• Critical for the immunogenicity of glycoconjugate vaccines such as pneumococcal CRM197.
• Involves diverse antigen-presenting cells including dendritic cells, macrophages, and enteric glial cells [1,3,5].
• Regulated by autophagy, which controls MHC class II expression in enteric glia.
• Modulated by signaling molecules such as protein kinase C delta and class I myosin Myo1e [4,6].
• Associated with N-glycan remodelling during MHC-II immunopeptide presentation.
• Relevant to intestinal inflammation and lymphocyte activation [3,5].
• Potential target for vaccine adjuvants and immunotherapies [7,8].
• Requires careful experimental models to distinguish polysaccharide from peptide presentation [1,8].
• Offers opportunities for CRISPR screening to identify novel regulators [4,5,6].
What Happens During antigen processing and presentation of polysaccharide antigen via MHC class II?
Uptake and intracellular trafficking of polysaccharide antigens
In simple terms: The antigen-presenting cell takes in the sugar antigen and moves it to the right compartment.
Polysaccharide antigens, such as zwitterionic capsular polysaccharides, are internalized by antigen-presenting cells and trafficked through endosomal compartments. The polysaccharide portion of the pneumococcal CRM197 conjugate vaccine co-localizes with MHC class II on the antigen processing cell surface, indicating that the antigen reaches MHC class II-containing compartments. This trafficking is distinct from classical protein antigen processing and may involve specialized endocytic pathways.
Association with MHC class II molecules
In simple terms: The sugar antigen binds to MHC class II molecules without being cut into pieces.
Unlike protein antigens that are proteolytically processed into peptides, polysaccharide antigens can associate with MHC class II molecules directly. Zwitterionic capsular polysaccharides are the new MHCII-dependent antigens, and their charge properties may facilitate binding to MHC class II. The polysaccharide portion of glycoconjugate vaccines co-localizes with MHC class II, supporting a direct loading mechanism.
Surface expression and T cell recognition
In simple terms: The cell displays the sugar-MHC complex on its surface so T cells can see it.
Once loaded, the polysaccharide-MHC class II complex is expressed on the cell surface. This surface display enables recognition by T cells, which can then become activated. Enteric glial cells can regulate lymphocyte activation via autophagy-mediated MHC-II expression, suggesting that surface presentation of polysaccharide antigens may occur in non-classical antigen-presenting cells.
Regulation by autophagy and signaling molecules
In simple terms: Cellular recycling and signaling pathways control how much antigen is presented.
Autophagy regulates MHC class II expression in enteric glia, and this pathway influences lymphocyte activation. Protein kinase C delta stimulates antigen presentation by class II MHC in murine dendritic cells. Class I myosin Myo1e regulates TLR4-triggered macrophage spreading, chemokine release, and antigen presentation via MHC class II. These findings indicate that polysaccharide antigen presentation via MHC class II is subject to multiple layers of regulation.
N-glycan remodelling during MHC-II presentation
In simple terms: Sugar modifications on MHC molecules change during antigen presentation.
Profound N-glycan remodelling accompanies MHC-II immunopeptide presentation. This remodelling may affect the stability, trafficking, or antigen-loading capacity of MHC class II molecules, potentially influencing polysaccharide antigen presentation. The interplay between glycosylation and polysaccharide antigen display remains an active area of research.
Key Genes Involved in GO:0002505 antigen processing and presentation of polysaccharide antigen via MHC class II
The following genes and proteins have been experimentally implicated in MHC class II antigen presentation, polysaccharide antigen handling, or related regulatory pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| H2-Aa | MHC class II alpha chain; forms the peptide-binding groove | Core component for polysaccharide antigen display |
| H2-Ab1 | MHC class II beta chain; pairs with alpha chain | Essential for MHC class II surface expression |
| CD74 | MHC class II invariant chain; chaperones MHC class II | Regulates antigen loading and trafficking |
| Myo1e | Class I myosin; regulates macrophage spreading and antigen presentation | Modulates MHC class II presentation |
| Prkcd | Protein kinase C delta; stimulates antigen presentation | Enhances class II MHC presentation in dendritic cells |
| Atg5 | Autophagy-related protein; required for autophagosome formation | Controls autophagy-mediated MHC-II expression |
| Atg7 | Autophagy-related protein; essential for autophagy | Regulates MHC-II expression in enteric glia |
| Tlr4 | Toll-like receptor 4; senses LPS | Triggers Myo1e-dependent antigen presentation |
| Cd11c | Integrin alpha X; marker for dendritic cells and macrophages | Identifies antigen-presenting cell populations |
| MHCII | Major histocompatibility complex class II | Directly presents polysaccharide antigens [7,8] |
| GM-CSF | Granulocyte-macrophage colony-stimulating factor | Used to generate antigen-presenting cell cultures |
| CRM197 | Mutant diphtheria toxin carrier protein | Conjugate vaccine carrier for polysaccharide antigens |
| CD4 | T cell co-receptor for MHC class II | Mediates T cell recognition of polysaccharide-MHCII |
| LAMP1 | Lysosomal-associated membrane protein 1 | Marks endosomal/lysosomal compartments for antigen processing |
| Rab7 | Late endosomal GTPase | Regulates trafficking to MHC class II compartments |
| Cathepsin S | Cysteine protease; degrades invariant chain | Facilitates MHC class II peptide loading |
| GILZ | Glucocorticoid-induced leucine zipper | Modulates MHC class II expression in glia |
| LC3 | Autophagosome marker | Monitors autophagy involved in MHC-II presentation |
How Is antigen processing and presentation of polysaccharide antigen via MHC class II Regulated?
The process of antigen processing and presentation of polysaccharide antigen via MHC class II is regulated at multiple levels. Autophagy controls MHC class II expression in enteric glial cells, and inhibition of autophagy reduces lymphocyte activation. Protein kinase C delta stimulates antigen presentation by class II MHC in murine dendritic cells, indicating a role for PKC signaling. Class I myosin Myo1e is required for TLR4-triggered macrophage spreading and antigen presentation via MHC class II, linking innate immune sensing to adaptive antigen display. Additionally, N-glycan remodelling during MHC-II immunopeptide presentation may influence the efficiency of polysaccharide antigen loading and surface expression. These regulatory mechanisms provide potential targets for modulating immune responses to polysaccharide antigens.
antigen processing and presentation of polysaccharide antigen via MHC class II and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| H2-Aa | Impaired polysaccharide antigen presentation | H2-Aa knockout mouse dendritic cells |
| Atg5 | Intestinal inflammation due to defective autophagy | Atg5 conditional knockout in enteric glia |
| Myo1e | Defective macrophage antigen presentation | Myo1e knockout macrophages |
| Prkcd | Reduced dendritic cell antigen presentation | Prkcd knockout dendritic cells |
| CD74 | Defective MHC class II loading and trafficking | CD74 knockout antigen-presenting cells |
Infectious diseases caused by encapsulated bacteria
Polysaccharide antigens from encapsulated bacteria such as Streptococcus pneumoniae are targets of glycoconjugate vaccines, and MHC class II-dependent presentation of these polysaccharides is critical for T cell help and vaccine efficacy [7,8]. Defects in this pathway could impair immunity to encapsulated pathogens.
Intestinal inflammation and autoimmune responses
Enteric glial cells regulate lymphocyte activation via autophagy-mediated MHC-II expression, and dysregulation of this process may contribute to intestinal inflammation [3,5]. Aberrant presentation of polysaccharide antigens could lead to inappropriate T cell activation in the gut.
Vaccine design and immunogenicity
The polysaccharide portion of the pneumococcal CRM197 conjugate vaccine co-localizes with MHC class II on antigen-presenting cells, highlighting the importance of this pathway for conjugate vaccine immunogenicity. Understanding GO:0002505 can guide the development of next-generation glycoconjugate vaccines.
From antigen processing and presentation of polysaccharide antigen via MHC class II-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate polysaccharide antigen presentation? | CRISPR knockout in GM-CSF bone marrow-derived dendritic cells |
| Does a point mutation in MHC class II affect polysaccharide binding? | CRISPR point mutation knock-in in H2-Aa |
| Can a tagged MHC class II track polysaccharide antigen co-localization? | Knock-in of fluorescent tag on H2-Ab1 |
| Does overexpression of Myo1e enhance antigen presentation? | Lentiviral overexpression in macrophages |
| Which autophagy genes are required for MHC-II expression? | CRISPR library screening in enteric glial cells |
| Does PKC delta activation boost polysaccharide presentation? | Pharmacological activation in dendritic cells |
How to Study the antigen processing and presentation of polysaccharide antigen via MHC class II Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Flow cytometry | Surface MHC class II and antigen co-localization | Quantify polysaccharide presentation [1,8] |
| Confocal microscopy | Intracellular trafficking and co-localization | Visualize antigen-MHCII complexes |
| CRISPR knockout | Gene requirement for antigen presentation | Test Myo1e, Prkcd, Atg5 [4,5,6] |
| CRISPR knock-in | Tagged or mutant MHC class II | Track antigen loading |
| Autophagy flux assay | LC3 turnover and autophagic activity | Link autophagy to MHC-II expression |
| ELISPOT | T cell activation by polysaccharide antigens | Measure functional presentation |
| Immunoprecipitation | MHC class II-associated polysaccharides | Identify antigen-MHCII complexes |
| RNA-seq | Transcriptional changes in antigen-presenting cells | Discover regulators of GO:0002505 |
Flow cytometry and immunophenotyping
Flow cytometry can quantify surface MHC class II and polysaccharide antigen co-localization on antigen-presenting cells [1,8]. This method is used to assess the efficiency of polysaccharide antigen presentation in different cell populations.
Confocal microscopy and co-localization analysis
Confocal microscopy allows visualization of polysaccharide antigens co-localizing with MHC class II and endosomal markers such as LAMP1 and Rab7. This approach reveals intracellular trafficking routes.
CRISPR knockout and knock-in models
CRISPR-Cas9 knockout of candidate genes (e.g., Myo1e, Prkcd, Atg5) in antigen-presenting cells can test their requirement for polysaccharide antigen presentation [4,5,6]. Knock-in of tags or point mutations can dissect molecular mechanisms.
Autophagy flux assays
LC3 turnover and autophagy flux assays measure autophagic activity, which regulates MHC class II expression in enteric glia. These assays link autophagy to polysaccharide antigen presentation.
How CRISPR Can Be Used to Study GO:0002505 antigen processing and presentation of polysaccharide antigen via MHC class II
Knockout
CRISPR knockout of genes such as Myo1e, Prkcd, or Atg5 in antigen-presenting cells can determine their necessity for polysaccharide antigen presentation via MHC class II [4,5,6]. Knockout models are valuable for identifying essential regulators and for validating drug targets.
Point Mutation
Point mutations in MHC class II genes or in regulatory proteins can be introduced using CRISPR base editing or homology-directed repair to dissect specific residues required for polysaccharide binding or signaling. Such models help distinguish binding versus signaling functions.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) on MHC class II or on polysaccharide antigens enables real-time tracking of antigen presentation. Tagged knock-in models are useful for imaging and biochemical studies.
Overexpression
Overexpression of candidate genes such as Myo1e or Prkcd via lentiviral vectors can test sufficiency for enhanced polysaccharide antigen presentation [4,6]. Overexpression models are complementary to knockout studies.
How EDITGENE Supports antigen processing and presentation of polysaccharide antigen via MHC class II Research
Researchers studying antigen processing and presentation of polysaccharide antigen via MHC class II-related genes often need to determine whether a candidate gene is causally involved in this pathway or merely correlated with it. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic interrogation of this process.
Contact EDITGENE today to design your custom CRISPR model for antigen processing and presentation of polysaccharide antigen via MHC class II research.
Frequently Asked Questions About antigen processing and presentation of polysaccharide antigen via MHC class II
What is GO:0002505?
GO:0002505 is the Gene Ontology term for antigen processing and presentation of polysaccharide antigen via MHC class II, the process by which an antigen-presenting cell displays a polysaccharide antigen on its surface in association with MHC class II.
What genes are involved in antigen processing and presentation of polysaccharide antigen via MHC class II?
Key genes include MHC class II subunits (H2-Aa, H2-Ab1), Myo1e, Prkcd, Atg5, Atg7, and CD74, among others [2,4,5,6,7].
How is polysaccharide antigen presented by MHC class II?
Zwitterionic capsular polysaccharides can directly associate with MHC class II molecules without proteolytic processing, and the polysaccharide portion of glycoconjugate vaccines co-localizes with MHC class II on the cell surface [7,8].
What cell types present polysaccharide antigens via MHC class II?
Dendritic cells, macrophages, and enteric glial cells have been shown to express MHC class II and participate in this process [1,3,5].
What is the role of autophagy in MHC class II presentation of polysaccharides?
Autophagy regulates MHC class II expression in enteric glia, and inhibition of autophagy reduces lymphocyte activation, suggesting a role in polysaccharide antigen presentation.
How does Myo1e regulate antigen presentation?
Class I myosin Myo1e regulates TLR4-triggered macrophage spreading, chemokine release, and antigen presentation via MHC class II.
Does protein kinase C delta affect MHC class II presentation?
Yes, protein kinase C delta stimulates antigen presentation by class II MHC in murine dendritic cells.
What is the link between N-glycan remodelling and MHC-II presentation?
Profound N-glycan remodelling accompanies MHC-II immunopeptide presentation, which may influence polysaccharide antigen loading.
What experimental models are used to study GO:0002505?
GM-CSF mouse bone marrow cultures, knockout mice, and CRISPR-edited cell lines are commonly used [1,4,5,6].
Why is polysaccharide antigen presentation via MHC class II important for vaccines?
It is critical for T cell help in glycoconjugate vaccines such as the pneumococcal CRM197 conjugate, enhancing immunogenicity.
Conclusion
GO:0002505 defines a unique antigen presentation pathway in which polysaccharide antigens are displayed on MHC class II molecules, bridging innate and adaptive immunity. This process is essential for responses to encapsulated bacteria and for glycoconjugate vaccine efficacy, and it is regulated by autophagy, Myo1e, PKC delta, and N-glycan remodelling [2,4,5,6,7,8]. Continued research using CRISPR models will uncover new regulators and therapeutic opportunities. EDITGENE provides the tools to interrogate this pathway with precision.
References
- 1. Helft J et al.. 2015. GM-CSF Mouse Bone Marrow Cultures Comprise a Heterogeneous Population of CD11c(+)MHCII(+) Macrophages and Dendritic Cells.. Immunity 42(6):1197-211 PMID: 26084029
- 2. Goodson H et al.. 2023. Profound N-glycan remodelling accompanies MHC-II immunopeptide presentation.. Front Immunol 14:1258518 PMID: 38022636
- 3. Brown RM et al.. 2025. Functional analysis of antigen presentation by enteric glial cells during intestinal inflammation.. Glia 73(2):291-308 PMID: 39495092
- 4. Wenzel J et al.. 2015. Class I myosin Myo1e regulates TLR4-triggered macrophage spreading, chemokine release, and antigen presentation via MHC class II.. Eur J Immunol 45(1):225-37 PMID: 25263281
- 5. Chow AK et al.. 2021. Enteric Glia Regulate Lymphocyte Activation via Autophagy-Mediated MHC-II Expression.. Cell Mol Gastroenterol Hepatol 12(4):1215-1237 PMID: 34166814
- 6. Majewski M et al.. 2007. Protein kinase C delta stimulates antigen presentation by Class II MHC in murine dendritic cells.. Int Immunol 19(6):719-32 PMID: 17446207
- 7. Cobb BA et al.. 2005. Zwitterionic capsular polysaccharides: the new MHCII-dependent antigens.. Cell Microbiol 7(10):1398-403 PMID: 16153240
- 8. Lai Z et al.. 2009. Antigen processing of glycoconjugate vaccines; the polysaccharide portion of the pneumococcal CRM(197) conjugate vaccine co-localizes with MHC II on the antigen processing cell surface.. Vaccine 27(24):3137-44 PMID: 19446183
