MCI Part 1 Chapter 2 Antigens and Antigen Recognition 23-24

An autoimmune disease occurs.

Viruses, bacteria, fungi, protozoa (Amoeba).

siRNA can be used to interfere with oncogene expression.

Polysaccharide antigens vary in immunogenicity and are more immunogenic if they have high molecular weight.

They can be used for drug delivery without provoking an undesirable host immune response.

Protein antigens.

The smallest unit of an antigen to which an antibody or immune cell can bind.

T cells recognize processed peptide epitopes (approximately 10 amino acids) that are presented on MHC molecules.

Some T cells.

Two antigen binding sites called paratopes.

The similarity of some epitopes or antigens.

Because it can capture more antigens.

Above 100,000 molecular weight (M.W.).

No, they are poor immunogens.

Toxins, worms, anesthetic procedures.

3D structure (i.e., conformation) of unprocessed antigens.

Some glycolipids and phospholipids.

More chemically complex antigens are more likely to be recognized by the immune system and provoke a response.

An immunogen is a type of antigen that is capable of inducing an immune response.

Because it has 10 binding sites.

It increases the sensitivity of disease screening.

α and β chains.

Nucleic acid antigens.

Molecules that can be recognized by the immune system (e.g., B-cell receptor or T-cell receptor).

Haptens can react with specific antibodies but cannot induce any immune response.

No, conformational epitopes cannot be determined by the same antibody if they are denatured, but the linear part exposed can still be determined.

Antigen-presenting cells (APCs) such as dendritic cells.

An antigen is a substance that can be recognized by the immune system and can provoke an immune response.

IgG.

Higher sensitivity of disease screening.

Because it can efficiently eliminate antigens.

2α and 2β domains.

Non-self antigens.

Microbes, parasites, toxins, viruses, bacteria, fungi, protozoa (Amoeba), worms, anesthetic procedures.

A shell of nucleic acids conjugated to solid nanoparticles.

Because proteins are usually large, complex structures with multiple epitopes.

The secreted form of IgM is a pentamer (10 binding sites), while the membrane-bound form is a monomer (2 binding sites).

Glycoproteins that bind antigens with high specificity and affinity.

Cell-mediated immune response.

The ability of an antibody to react with more than one epitope or antigen.

IgG.

Only on the surface of T-cell membranes.

Production of conjugate vaccines.

On self MHC molecules.

No, very small molecules are non-immunogenic.

Non-self and self.

Linear epitopes (6-8 contiguous amino acids) and conformational epitopes (protein segments folded into a tertiary structure).

Phagocytes and antigen-presenting cells.

MHC II.

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.

Factors that determine immunogenicity include the antigen's foreignness, size, complexity, and the presence of adjuvants.

In the thymus.

Peptide fragments from intracellular antigens.

Macrophages engulf pathogens, process their antigens, and present them on MHC molecules to T-cells.

Raw eggs are more immunogenic than boiled eggs.

High molecular weight increases the immunogenicity of polysaccharide antigens.

No, not all antigens are immunogens.

B cells secrete antibodies with antigen-binding sites identical to those on their BCR.

Immunogenicity is the ability of an antigen to provoke an immune response.

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.

Adjuvants can enhance the immunogenicity of an antigen by boosting the immune response.

Antigens can be recognized by different molecules such as antibodies, B-cell receptors, and T-cell receptors.

It lowers the specificity of diagnostics.

Constant and variable regions.

Peptide fragments from extracellular antigens.

TCRs recognize antigens that are presented by Major Histocompatibility Complex (MHC) molecules on the surface of antigen-presenting cells.

Cytokines are signaling molecules that modulate the immune response, including the activation and differentiation of T-cells.

They are weak immunogens.

Antigens that can stimulate an immune response.

Polysaccharides, peptides, and proteins; some may contain lipids and nucleic acids.

Pattern recognition receptors (PRRs).

An inflammatory response leading to the killing of pathogens.

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.

Common types of antigens include non-self antigens (foreign substances) and self-antigens (normal body components).

IgM.

Hapten + carrier protein = immunogenic complex.

MHC molecules are cell surface proteins that present antigen fragments to T-cells, facilitating their recognition.

The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens and damaged cells, and promotes inflammation.

Complex antigens with multiple epitopes can be recognized by antibodies or immune cells, leading to increased immunogenicity.

Examples include ABO blood group antigens and bacterial capsule.

Yes, all immunogens are antigens.

A membrane-bound antibody molecule (IgM and IgD isotypes).

B cells recognize native, unprocessed antigens with epitopes formed by various molecules such as peptides, carbohydrates, and lipopolysaccharides.

Pathogen-associated molecular patterns (PAMPs).

Antigen binding (Fab) and constant (Fc) fragments.

Different genetic backgrounds can influence how well an individual's immune system recognizes and responds to a given antigen.

Lower specificity and lower diagnostic accuracy.

Small antigenic determinants that are non-immunogenic (e.g., drugs, simple sugars, amino acids, lipids, etc.).

On antigen-presenting cells.

CD8 on cytotoxic T (Tc) cells.

Dendritic cells capture antigens, process them, and present them on MHC molecules to T-cells, initiating an immune response.

Proteins in boiled eggs become denatured, reducing their immunogenicity.

Yes, parasites can act as antigens.

Small antigenic determinants on antigens that can be recognized by an antibody.

Lipid antigens are weakly immunogenic.

Larger antigens are generally more immunogenic than smaller ones.

The strength of binding between an epitope and an antigen binding site.

Variable heavy (VH) and light (VL) chains.

To present antigens and discriminate self from non-self.

On the surface of all nucleated cells.

They form the antigen-binding sites.

CD4 on helper T (Th) cells.

APCs process and present antigens on their surface using MHC molecules to T-cells.

Denaturation, strong heat, or extreme pH.

Yes, they bind to the same area that the BCR binds to.

The overall binding strength between multiple epitopes and antigen binding sites.

IgM, IgD, IgG, IgA, and IgE.

3α and 1β domains.

By attaching covalently to larger carrier molecules (e.g., proteins).

BCRs recognize and bind to specific antigens directly on the surface of pathogens.

CD80 and CD86 on APCs, which interact with CD28 on T-cells.

CD8+ cytotoxic T cells.

Antibodies bind to specific antigens to neutralize them or mark them for destruction by other immune cells.

Co-stimulatory molecules provide necessary secondary signals to T-cells, ensuring a full immune response.

Processed peptide antigen fragments displayed on MHC molecules.

Antibodies, B-cell receptors (BCRs), and T-cell receptors (TCRs).

B-cells can act as APCs by presenting antigens on MHC class II molecules to helper T-cells.

CD4+ helper T cells.

Dendritic cells, macrophages, and B-cells.

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.