What type of antigens are more immunogenic?
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Non-self antigens.
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What type of antigens are more immunogenic?
Non-self antigens.
What is the relationship between antigen complexity and immunogenicity?
Complex antigens with multiple epitopes can be recognized by antibodies or immune cells, leading to increased immunogenicity.
How can non-self antigens be presented?
On self MHC molecules.
What is the molecular weight threshold above which molecules are considered most potent immunogens?
Above 100,000 molecular weight (M.W.).
Which are more immunogenic, raw eggs or boiled eggs?
Raw eggs are more immunogenic than boiled eggs.
What happens if we are not tolerant to self antigens?
An autoimmune disease occurs.
What type of antigens are polysaccharide antigens?
Polysaccharide antigens vary in immunogenicity and are more immunogenic if they have high molecular weight.
How are molecules with a molecular weight less than 10,000 classified in terms of immunogenicity?
They are weak immunogens.
What type of antigens are nucleic acids?
Nucleic acid antigens.
What happens to proteins in boiled eggs that affects their immunogenicity?
Proteins in boiled eggs become denatured, reducing their immunogenicity.
What are some examples of antigens?
Microbes, parasites, toxins, viruses, bacteria, fungi, protozoa (Amoeba), worms, anesthetic procedures.
What are examples of polysaccharide antigens?
Examples include ABO blood group antigens and bacterial capsule.
Are very small molecules, such as a single amino acid, immunogenic?
No, very small molecules are non-immunogenic.
Are nucleic acid antigens considered good immunogens?
No, they are poor immunogens.
What types of microorganisms can act as antigens?
Viruses, bacteria, fungi, protozoa (Amoeba).
What factor increases the immunogenicity of polysaccharide antigens?
High molecular weight increases the immunogenicity of polysaccharide antigens.
What is a potential application of spherical nucleic acids?
They can be used for drug delivery without provoking an undesirable host immune response.
What are immunogens?
Antigens that can stimulate an immune response.
What are antigens?
Molecules that can be recognized by the immune system (e.g., B-cell receptor or T-cell receptor).
Can parasites act as antigens?
Yes, parasites can act as antigens.
What is the structure of spherical nucleic acids?
A shell of nucleic acids conjugated to solid nanoparticles.
Are all immunogens antigens?
Yes, all immunogens are antigens.
What are the two major types of antigens?
Non-self and self.
What are some non-microbial examples of antigens?
Toxins, worms, anesthetic procedures.
What is the role of small interfering RNA (siRNA) in the context of nucleic acid antigens?
siRNA can be used to interfere with oncogene expression.
Are all antigens immunogens?
No, not all antigens are immunogens.
What are the most common and most immunogenic antigens?
Protein antigens.
What are the common components of antigens?
Polysaccharides, peptides, and proteins; some may contain lipids and nucleic acids.
What is an example of an antigen that is not an immunogen?
Haptens can react with specific antibodies but cannot induce any immune response.
What are epitopes?
Small antigenic determinants on antigens that can be recognized by an antibody.
Why are protein antigens highly immunogenic?
Because proteins are usually large, complex structures with multiple epitopes.
What is a B-cell receptor (BCR)?
A membrane-bound antibody molecule (IgM and IgD isotypes).
What types of epitopes do protein antigens consist of?
Linear epitopes (6-8 contiguous amino acids) and conformational epitopes (protein segments folded into a tertiary structure).
What type of antigens does the B-cell receptor (BCR) recognize?
3D structure (i.e., conformation) of unprocessed antigens.
What can destroy conformational epitopes?
Denaturation, strong heat, or extreme pH.
What happens when B cells are stimulated with an antigen?
B cells secrete antibodies with antigen-binding sites identical to those on their BCR.
What is an epitope?
The smallest unit of an antigen to which an antibody or immune cell can bind.
What does the innate immune system use to recognize pathogen-associated molecular patterns (PAMPs)?
Pattern recognition receptors (PRRs).
Can the same antibody determine both linear and conformational epitopes?
No, conformational epitopes cannot be determined by the same antibody if they are denatured, but the linear part exposed can still be determined.
What is the immunogenicity of lipid antigens?
Lipid antigens are weakly immunogenic.
How does the secreted form of IgM differ from the membrane-bound form?
The secreted form of IgM is a pentamer (10 binding sites), while the membrane-bound form is a monomer (2 binding sites).
How do B cells recognize antigens?
B cells recognize native, unprocessed antigens with epitopes formed by various molecules such as peptides, carbohydrates, and lipopolysaccharides.
Which cells mainly express pattern recognition receptors (PRRs)?
Phagocytes and antigen-presenting cells.
Which types of lipids can be presented by APCs?
Some glycolipids and phospholipids.
Do the secreted antibodies bind to the same area as the BCR?
Yes, they bind to the same area that the BCR binds to.
What is immunogenicity?
Immunogenicity is the ability of an antigen to provoke an immune response.
How do T cells recognize antigens?
T cells recognize processed peptide epitopes (approximately 10 amino acids) that are presented on MHC molecules.
What can the binding of PRRs to PAMPs result in?
An inflammatory response leading to the killing of pathogens.
Which cells present lipid antigens on CD1?
Antigen-presenting cells (APCs) such as dendritic cells.
How does the size of an antigen affect its immunogenicity?
Larger antigens are generally more immunogenic than smaller ones.
What are antibodies?
Glycoproteins that bind antigens with high specificity and affinity.
What are common antigens that exist on the surface of bacteria and fungi?
Pathogen-associated molecular patterns (PAMPs).
What is CD1 functionally similar to?
MHC II.
Why is the chemical complexity of an antigen important for its immunogenicity?
More chemically complex antigens are more likely to be recognized by the immune system and provoke a response.
Which cells recognize lipid antigens presented on CD1?
Some T cells.
What is the basic structure of an antibody?
A Y-shaped structure formed by 4 polypeptide chains: 2 identical pairs of light (L) chains and heavy (H) chains joined together by disulphide bonds.
How does the dose of an antigen influence its immunogenicity?
Both very low and very high doses of an antigen can lead to low immunogenicity, while an optimal intermediate dose is more likely to provoke a strong immune response.
What is an antigen?
An antigen is a substance that can be recognized by the immune system and can provoke an immune response.
What is antibody affinity?
The strength of binding between an epitope and an antigen binding site.
What type of immune response is triggered by the recognition of lipid antigens by T cells?
Cell-mediated immune response.
What are the two main fragments of an antibody?
Antigen binding (Fab) and constant (Fc) fragments.
What role does the route of administration play in the immunogenicity of an antigen?
The route of administration (e.g., intravenous, subcutaneous, oral) can affect how well an antigen is recognized by the immune system and its subsequent immunogenicity.
What is an immunogen?
An immunogen is a type of antigen that is capable of inducing an immune response.
What is antibody avidity?
The overall binding strength between multiple epitopes and antigen binding sites.
How many antigen binding sites does an antibody have and what are they called?
Two antigen binding sites called paratopes.
How does the presence of adjuvants affect the immunogenicity of an antigen?
Adjuvants can enhance the immunogenicity of an antigen by boosting the immune response.
What are the common types of antigens?
Common types of antigens include non-self antigens (foreign substances) and self-antigens (normal body components).
Which immunoglobulin has high affinity for its target?
IgG.
Which chains form the antigen binding sites (paratopes) of an antibody?
Variable heavy (VH) and light (VL) chains.
What is antibody cross-reactivity?
The ability of an antibody to react with more than one epitope or antigen.
Why is the genetic makeup of the host important for the immunogenicity of an antigen?
Different genetic backgrounds can influence how well an individual's immune system recognizes and responds to a given antigen.
What factors determine the immunogenicity of antigens?
Factors that determine immunogenicity include the antigen's foreignness, size, complexity, and the presence of adjuvants.
Why does IgM have high avidity despite having low affinity binding sites?
Because it has 10 binding sites.
What are the five different classes of antibodies?
IgM, IgD, IgG, IgA, and IgE.
What causes antibody cross-reactivity?
The similarity of some epitopes or antigens.
How can antigens be recognized by the immune system?
Antigens can be recognized by different molecules such as antibodies, B-cell receptors, and T-cell receptors.
Which immunoglobulin is important in the primary immune response?
IgM.
What is a potential benefit of antibody cross-reactivity?
Higher sensitivity of disease screening.
What is the primary function of MHC molecules?
To present antigens and discriminate self from non-self.
Which immunoglobulin plays a role in the secondary immune response?
IgG.
What is a potential drawback of antibody cross-reactivity?
Lower specificity and lower diagnostic accuracy.
Where are T cells educated to respond only to foreign antigens presented by self MHC?
In the thymus.
How does antibody cross-reactivity affect disease screening?
It increases the sensitivity of disease screening.
What are the components of MHC class I molecules?
3α and 1β domains.
Why is IgM important in the primary immune response?
Because it can capture more antigens.
How does antibody cross-reactivity affect diagnostic specificity?
It lowers the specificity of diagnostics.
Why is IgG important in the secondary immune response?
Because it can efficiently eliminate antigens.
Where are MHC class I molecules located?
On the surface of all nucleated cells.
Where are T-cell receptors (TCR) found?
Only on the surface of T-cell membranes.
What are haptens?
Small antigenic determinants that are non-immunogenic (e.g., drugs, simple sugars, amino acids, lipids, etc.).
What type of antigens do MHC class I molecules present?
Peptide fragments from intracellular antigens.
What are the two polypeptide chains that make up the T-cell receptor (TCR)?
α and β chains.
How can haptens be made immunogenic?
By attaching covalently to larger carrier molecules (e.g., proteins).
Which T cells recognize MHC class I molecules?
CD8+ cytotoxic T cells.
What regions do the α and β chains of the T-cell receptor (TCR) have?
Constant and variable regions.
What is the formula for making a hapten immunogenic?
Hapten + carrier protein = immunogenic complex.
What are the components of MHC class II molecules?
2α and 2β domains.
What is the function of the variable regions of the α and β chains in T-cell receptors (TCR)?
They form the antigen-binding sites.
What is an application of haptens in medicine?
Production of conjugate vaccines.
Where are MHC class II molecules located?
On antigen-presenting cells.
What do T-cell receptors (TCR) recognize?
Processed peptide antigen fragments displayed on MHC molecules.
What type of antigens do MHC class II molecules present?
Peptide fragments from extracellular antigens.
Which co-receptor on T cells binds to MHC II molecules?
CD4 on helper T (Th) cells.
Which T cells recognize MHC class II molecules?
CD4+ helper T cells.
Which co-receptor on T cells binds to MHC I molecules?
CD8 on cytotoxic T (Tc) cells.
What are the primary molecules involved in the recognition of antigens?
Antibodies, B-cell receptors (BCRs), and T-cell receptors (TCRs).
What is the role of antibodies in antigen recognition?
Antibodies bind to specific antigens to neutralize them or mark them for destruction by other immune cells.
How do B-cell receptors (BCRs) recognize antigens?
BCRs recognize and bind to specific antigens directly on the surface of pathogens.
What is the function of T-cell receptors (TCRs) in antigen recognition?
TCRs recognize antigens that are presented by Major Histocompatibility Complex (MHC) molecules on the surface of antigen-presenting cells.
What are Major Histocompatibility Complex (MHC) molecules?
MHC molecules are cell surface proteins that present antigen fragments to T-cells, facilitating their recognition.
What is the difference between MHC class I and MHC class II molecules?
MHC class I molecules present antigens from intracellular pathogens to CD8+ T-cells, while MHC class II molecules present antigens from extracellular pathogens to CD4+ T-cells.
How do antigen-presenting cells (APCs) contribute to antigen recognition?
APCs process and present antigens on their surface using MHC molecules to T-cells.
What are the main types of antigen-presenting cells (APCs)?
Dendritic cells, macrophages, and B-cells.
What is the role of dendritic cells in antigen recognition?
Dendritic cells capture antigens, process them, and present them on MHC molecules to T-cells, initiating an immune response.
How do macrophages participate in antigen recognition?
Macrophages engulf pathogens, process their antigens, and present them on MHC molecules to T-cells.
What is the role of B-cells in antigen presentation?
B-cells can act as APCs by presenting antigens on MHC class II molecules to helper T-cells.
What is the significance of co-stimulatory molecules in antigen recognition?
Co-stimulatory molecules provide necessary secondary signals to T-cells, ensuring a full immune response.
What are some examples of co-stimulatory molecules?
CD80 and CD86 on APCs, which interact with CD28 on T-cells.
How do cytokines influence antigen recognition?
Cytokines are signaling molecules that modulate the immune response, including the activation and differentiation of T-cells.
What is the role of the complement system in antigen recognition?
The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens and damaged cells, and promotes inflammation.
