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Antigen Processing and Presentation
What is the primary focus of the lecture on September 30, 2024?
Antigen Processing and Presentation.
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Major Histocompatibility Complex (MHC)
What is the central role of MHC molecules?
To present antigens to T-cells.
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Differentiation of T-cell Subsets
How do MHC I and MHC II differ in terms of T cell recognition?
They are recognized by distinct T cell subsets and elicit different T cell responses.
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Role of Antigen Presenting Cells (APCs)
Where are immature dendritic cells typically found?
In peripheral tissues, where they capture antigens.
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Antigen Processing and Presentation
Which department is Dr. Marcsilla Holub associated with?
Department of Genetics, Cell - and Immunobiology.
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Differentiation of T-cell Subsets
What happens if a T-cell becomes Th1?
It migrates to the periphery.
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Role of Antigen Presenting Cells (APCs)
What is the role of macrophages in the cellular immune response?
They effectively clear bacteria.
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Major Histocompatibility Complex (MHC)
What are the components of MHC I?
A peptide, an alpha chain, and a beta-2 microglobulin.
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Cytosolic and Endosomal Antigen Pathways
What types of pathogens can be found inside a cell?
Viruses, tumor antigens, intracellular bacteria (e.g., Mycobacterium), and extracellular bacteria (e.g., Neisseria gonorrhea).
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Antigen Processing and Presentation
What is the role of the endosome in antigen processing?
It facilitates the uptake of exogenous antigens for MHC II presentation.
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Peptide Loading onto MHC Molecules
Which amino acids are structurally similar and important for anchoring in MHC Class I?
Tyrosine (Y), Phenylalanine (F), Leucine (L), Valine (V), and Isoleucine (I).
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Peptide Loading onto MHC Molecules
What type of peptides does TAP prefer for MHC I binding?
Peptides longer than 8 amino acids that are hydrophobic with carboxyl ends.
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Endogenous vs Exogenous Antigen Processing
What are the two main pathways of receiving antigens?
Cytosol-derived (endogenous Ags) and endosome/lysosome-derived (exogenous Ags).
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Major Histocompatibility Complex (MHC)
What is the relationship between MHC I and antigen peptides?
MHC I and antigen peptides are physically separated but connect within the cell.
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Major Histocompatibility Complex (MHC)
How do MHC and antigen peptides appear on the cell surface?
They appear always together on the cell surface.
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Major Histocompatibility Complex (MHC)
What types of peptides are presented by MHC I?
Self or viral protein peptides.
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Role of Antigen Presenting Cells (APCs)
What is the primary goal of antigen presentation by dendritic cells?
To induce activation and determine the differentiation of naive T-cells (priming).
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Cytosolic and Endosomal Antigen Pathways
What types of pathogens can be found inside a cell?
Viruses, tumor antigens, intracellular bacteria (e.g., Mycobacterium), and extracellular bacteria (e.g., Neisseria gonorrhea).
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Cytosolic and Endosomal Antigen Pathways
Where are pathogens and their products located within a cell?
In either the cytosol or in vesicles.
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Role of Antigen Presenting Cells (APCs)
What happens to immature dendritic cells upon activation?
They mature and enhance their ability to present antigens to T cells.
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B-cell Receptor and T-cell Receptor
How do B-lymphocytes select antigens?
By using their B-cell receptors (BCR).
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Human Leukocyte Antigens (HLA)
What are immunogenic alloantigen proteins?
Proteins on the cell surface that can provoke an immune response.
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T-cell Receptor and B-cell Receptor
What does the T-cell receptor recognize?
A complex of antigenic peptide and MHC.
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Major Histocompatibility Complex (MHC)
What is the role of MHC in TCR recognition?
MHC presents the antigenic peptide to the T-cell receptor.
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Major Histocompatibility Complex (MHC)
What is the role of the RER in relation to MHC I?
It is involved in the generation of MHC I + endogenous peptide complex.
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Major Histocompatibility Complex (MHC)
What is the role of MHC I in the immune response?
It presents endogenous peptides to cytotoxic T-lymphocytes.
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Role of Antigen Presenting Cells (APCs)
What is the primary function of immature dendritic cells?
To capture and process antigens before migrating to lymph nodes.
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Differentiation of T-cell Subsets
How do dendritic cells influence CD4 lymphocyte differentiation?
By presenting antigens and utilizing TLR signaling.
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Peptide Loading onto MHC Molecules
What is meant by N- and C-terminal overhangs in peptides?
They refer to the portions of the peptide that extend beyond the anchor residues.
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Cytosolic and Endosomal Antigen Pathways
What is the role of the lysosome in antigen processing?
Degradation of proteins into 11-25 amino acid peptides.
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Endogenous vs Exogenous Antigen Processing
How quickly is the viral peptide displayed on the surface of infected cells?
Within a very short time.
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Major Histocompatibility Complex (MHC)
What does MHC stand for?
Major Histocompatibility Complex.
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Role of Antigen Presenting Cells (APCs)
What is an immature dendritic cell?
A precursor form of dendritic cells that has not yet fully developed its antigen-presenting capabilities.
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Role of Antigen Presenting Cells (APCs)
What are professional antigen presenting cells (APCs)?
Cells that present antigens to T-cells, including dendritic cells and macrophages.
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Human Leukocyte Antigens (HLA)
What is the function of HLA-DM?
It helps separate CLIP and loads MHC II with peptides.
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Role of Antigen Presenting Cells (APCs)
What is the role of B-cells and macrophages in antigen presentation?
They present antigens to effector T-cells to receive signals for maturation.
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T-cell Receptor and B-cell Receptor
What is the role of B-cell receptors?
To recognize whole antigens and initiate B-cell activation.
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Human Leukocyte Antigens (HLA)
Are immunogenic alloantigen proteins present on all cells?
No, only on nucleated cells and some specific cells.
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Cytosolic and Endosomal Antigen Pathways
Where are pathogens and their products located within a cell?
In either the cytosol or in vesicles.
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Cytosolic and Endosomal Antigen Pathways
What is continuously degraded next to hydrophobic and basic amino acids?
Newly synthesized MHC I and its associated peptides.
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Major Histocompatibility Complex (MHC)
What does MHC II do?
It presents exogenous peptides to helper T-lymphocytes.
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Major Histocompatibility Complex (MHC)
What presents peptides on the surface of cells?
Major Histocompatibility Complex (MHC).
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Peptide Loading onto MHC Molecules
What structural feature do the important amino acids for MHC Class I anchoring have?
They are hydrophobic and contain phenol rings with 2 CH3 groups.
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Selectivity in Antigen Processing
What is the significance of peptide length in MHC I binding?
TAP selectively transports peptides that are greater than 8 amino acids long.
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Peptide Loading onto MHC Molecules
What complex is formed with MHC I?
Peptide + MHC I make a complex.
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Human Leukocyte Antigens (HLA)
What are HLA molecules?
Human Leukocyte Antigens.
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Major Histocompatibility Complex (MHC)
What are the components of MHC II?
A peptide, an alpha chain, and a beta chain.
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Peptide Loading onto MHC Molecules
What is the significance of the association between MHC and peptide?
It forms a tight association essential for antigen presentation.
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Peptide Loading onto MHC Molecules
What is the role of the chaperone complex in MHC I peptide binding?
It assists in the proper folding and assembly of MHC I for peptide binding.
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Significance of Antigen Presentation in Immune Response
Can you provide an example of an MHC I-elicited response?
Cytotoxic T cell response to viral infection.
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Antigen Processing and Presentation
What is required for ATP-dependent peptide transport in MHC I processing?
TAP (Transporter associated with Antigen Processing).
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Role of Antigen Presenting Cells (APCs)
What types of cells are included in phagocytes?
Natural dendritic cells and macrophages.
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Peptide Loading onto MHC Molecules
How are cytoplasmic peptides related to MHC I?
Cytoplasmic peptides become an integral part of MHC I.
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Peptide Loading onto MHC Molecules
What is the characteristic of peptides bound to MHC Class II molecules?
They lie at various distances from the ends of the peptide.
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Major Histocompatibility Complex (MHC)
What type of cells express MHC Class II molecules?
Professional antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells.
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Major Histocompatibility Complex (MHC)
What is the primary function of MHC molecules?
To present peptide antigens to T cells.
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Peptide Loading onto MHC Molecules
What is the role of HLA-DM?
It facilitates the loading of peptides onto MHC II.
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Human Leukocyte Antigens (HLA)
What do HLA molecules do in antigen presentation?
They present small antigen peptides to T-cells.
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Significance of Antigen Presentation in Immune Response
What is the significance of antigen presentation in the immune system?
It continuously informs the immune system about the outer and inner environment of various human cells.
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Antigen Processing and Presentation
What is the process of antigen uptake?
The process by which antigens are taken up for processing.
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Differentiation of T-cell Subsets
What role do dendritic cells play in the immune system?
They determine the differentiation pathway of CD4 lymphocytes.
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Peptide Loading onto MHC Molecules
Where does the partial degradation of Ii occur?
In the endoplasmic reticulum (RER) and Golgi apparatus.
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Human Leukocyte Antigens (HLA)
What is CLIP in the context of MHC II?
A peptide that is removed by HLA-DM to load MHC II with other peptides.
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Role of Antigen Presenting Cells (APCs)
What receptors do macrophages use to recognize antigens?
Complement receptors, Fc γ receptors, and lectin receptors.
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Role of Antigen Presenting Cells (APCs)
What is the role of mannose in antigen uptake?
It is recognized by specific receptors on B-cells.
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Cytosolic and Endosomal Antigen Pathways
What types of peptides are processed in the cytosol?
Normal self, transformed self (tumor), and viral peptides.
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Endogenous vs Exogenous Antigen Processing
What are the two main types of antigen processing?
Endogenous and exogenous antigen processing.
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Cytosolic and Endosomal Antigen Pathways
What is the role of the proteasome in antigen processing?
Degradation of proteins into 8-9 amino acid peptides.
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T-cell Receptor and B-cell Receptor
What is the role of T-cell receptors?
To recognize specific antigens presented by antigen presenting cells.
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Peptide Loading onto MHC Molecules
What is the function of TAP1 and TAP2?
They transport peptides into the RER for loading onto MHC I.
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Peptide Loading onto MHC Molecules
What stabilizes peptides bound to MHC Class I molecules?
The amino and carboxy termini of the peptide.
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Significance of Antigen Presentation in Immune Response
Can you provide an example of an MHC II-elicited response?
Helper T cell activation in response to bacterial infection.
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Peptide Loading onto MHC Molecules
What is CLIP in the context of MHC II processing?
CLIP is a fragment resulting from the partial degradation of Ii.
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Peptide Loading onto MHC Molecules
What happens to the MHC II complex in the acidic lysosome?
It binds to exogenous peptide to form the MHC II + exogenous peptide complex.
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Peptide Loading onto MHC Molecules
How is the length of peptides bound to MHC Class II molecules described?
Peptides are variable in length.
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Major Histocompatibility Complex (MHC)
What does MHC stand for?
Major Histocompatibility Complex.
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Major Histocompatibility Complex (MHC)
How do MHC Class I and Class II molecules differ in their peptide binding?
MHC Class I binds peptides that are 8-10 amino acids long, while MHC Class II binds longer peptides, typically 13-25 amino acids.
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Role of Antigen Presenting Cells (APCs)
What do antigen presenting cells (APCs) do?
They process and present antigens to T-cells.
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Major Histocompatibility Complex (MHC)
Which cells present MHC II?
Special antigen-presenting cells (APCs).
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Peptide Loading onto MHC Molecules
What is the significance of the peptides generated in the RER?
They are used to form complexes with MHC I for presentation.
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Major Histocompatibility Complex (MHC)
What are the two main classes of MHC molecules?
MHC Class I and MHC Class II.
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Major Histocompatibility Complex (MHC)
What is the function of MHC molecules?
To present processed peptides to T-cells.
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Peptide Loading onto MHC Molecules
What are anchor residues in the context of MHC Class II molecules?
Anchor residues are fixed places within the peptide.
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Significance of Antigen Presentation in Immune Response
What is the difference between linear and conformational epitopes?
Linear epitopes are processed peptides, while conformational epitopes are whole molecules.
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Role of Antigen Presenting Cells (APCs)
What is C3b's role in antigen uptake?
It acts as an opsonin that enhances phagocytosis.
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Cytosolic and Endosomal Antigen Pathways
What is the role of the proteasome in peptide processing?
It cleaves proteins into peptides.
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Peptide Loading onto MHC Molecules
What is TAP and its function?
TAP inserts peptides into the Rough Endoplasmic Reticulum (RER).
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T-cell Receptor and B-cell Receptor
What recognizes the MHC I-peptide complex?
Cytotoxic T lymphocytes (Tc).
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Major Histocompatibility Complex (MHC)
Where is a large amount of MHC I found?
In the Rough Endoplasmic Reticulum (RER).
