Antigens and MHC

Antigens

Substances which trigger an immune response and create memory are?

Antigenicity, specificity, and immunogeniticy

Antigens have which three properties?

The quality of an antigen to serve as a ligand

How is antigenicity defined?

Specificity

The antigen quality to be a unique molecule is known as?

The quality to induce immune responses

What is the immunogenicity of an antigen?

Epitope; gives specificity

A specific sequence of 10-15 amino acids of an antigen is known as its ___. What is the purpose of this section?

Molecular patterns; PAMPs and DAMPs

Which substances are able to trigger an immune response with no memory?

True

True or False: Haptens are not capable of eliciting an immune response on their own

Both the antigen it recognizes and by the MHC molecule bound to it

The specificity of a T-cell receptor is defined by?

Linear peptides

What kind of peptides do T cells recognize?

Helper cells; MHC class II

CD4 T cells, also known as ___ cells, recognize which class of MHC molecules?

CD8 T cells, or cytotoxic T cells

MHC class I molecules present antigens to which class of T cells?

Rejection of non-individual tissue

MHC was discovered based on what?

MHC II

Which MHC class is responsible for presenting extracellular antigens to T cells?

Intracellular

CD8+ T cells primarily kill which pathogen type?

Major Histocompatibility Complex; found on chromosomes

What is MHC and where is it found?

Polymorphic

MHC genes are the most ___ genes in the mammalian genome

Polygenic, polymorphic, and codominant

What are the properties of all MHC molecules?

Multiple alleles which occupy that location within a population

A gene that is polymorphic has?

False

True or False: Only one type of MHC will be expressed in a heterozygous individual

I

Most individuals express 6-8 different class ___ MHC molecules on every cell

6 to 8

How many pairs of MHC II molecules are expressed in most individuals?

It becomes more difficult for pathogens to evade immune responses

What is the purpose of having multiple different types of MHC molecules?

As the number of unique MHC molecules increases, there is an increased risk of autoimmune disease

Why do animals not express an even greater number of different MHC molecules?

An alpha chain, beta 2-microglobulin, and a bound peptide

Stable expression of class I MHC molecules on cell surfaces requires he presence of what components?

One alpha chain, one beta chain, and a bound peptide

MHC class II molecules consist of what parts>

Antigen presenting cells; dendritic cells, B cells, and macrophages

Class II MHC molecules are presented on which cell type? Examples?

Cytokines

The expression of MHC II molecules is increased by what signals during immune responses?

MHC II to CD4 T cells

Endothelial and epithelial cells during thymus selection present antigen on?

Three

Activation and differentiation of naive T cells requires ___ signals

Antigen-specific signaling mediated by MHC

The first signal required for activation of T cells is?

Costimulatory signaling

The second signal required for T cell activation includes?

Polarizing signaling by cytokines

The third signal required for T cell activation is?

Extracellular pathogens

Which pathogens are presented via the exogenous pathway?

MHC class II, CD4+ T cells

Within the exogenous pathway, antigens are presented on ___ and activate ___

Endogenous pathway

Which pathway activates CD8+ T cells?

Within the cytosol

The endogenous pathway is used in the case of peptides located where?

Converts the antigen from a protein into a recognizable linear peptide

What does antigen processing achieve?

Antigen presentation

Displaying peptides on MHC molecules is broadly known as?

Antigens are ingested into vesicles and then displayed by class I MHC molecules

Describe the process of antigen cross-presentation

The site of proteolysis

Antigen processing is determined by what?

Prevents self-peptide form being incorporated into the antigen

What is the purpose of the invariant chain?

Dendritic cells

Which antigen presenting cells are involved in cross presentation?

In the endosome

In the MHC class II pathway, the peptide is degraded where?

The invariant chain is cleaved

Once the MHC class II complex is within the endosome, what occurs for the peptide to be able to interact with the complex?

Massive production of cytokines by CD4 T cells

In the response to superantigens, what cells are released?

Systemic toxicity and suppression of the adaptive immune response

The mass release of cytokines from a superantigen has what effects?

In the proteasome

The MHC class I pathway is processes where?

False

True or False: Polygenic in MHC genes means multiple alleles at one locus

False

True or False: Polymorphism in MHC genes means multiple different genes occupy that genomic location

B

What does MHC class I do?

A. Presents peptides to CD4 "helper" T lymphocytes.

B. Presents peptides to CD8 "cytotoxic" T lymphocytes.

C. Brings peptides from the phagosome to the cell surface.

D. It is released from cells to float freely and bind to CD8.

B

Which of the following cell types is not considered a

professional antigen-presenting cell?

A. macrophage

B. neutrophil

C. B cell

D. dendritic cell

C

A research assistant observes a cell with an internal defect that

causes accumulation of misfolded proteins in the cytosol that

must be processed for potential presentation on class I MHC.

According to the class I MHC pathway, which cellular component

is primarily responsible for breaking down misfolded cytosolic

proteins into peptides?

A. Cytosol

B. Endosomes

C. Proteasome

D. TAP transporter

A

What does MHC class II do?

A. Presents peptides to CD4 "helper" T lymphocytes.

B. Presents peptides to CD8 "cytotoxic" T lymphocytes.

C. Makes antibody.

D. Removes worn out proteins.

C

MHC class I molecules are primarily involved in?

A. Recognition of glycolipid antigens

B. Resistance to extracellular bacteria

C. Resistance to viruses

D. Activation of neutrophils

D

What is MHC restriction?

A. It is a process of presenting exogenous antigen to CD8 T.

B. It is a process of presenting cytosolic antigens on MHC class I.

C. It is a process occurs during B cell development.

D. It is the phenomenon where T cells will recognize a unique set

of peptides bound to a particular MHC molecule.

B

How MHC polymorphisms benefit the immune response?

A. Brings less peptides from the proteasome to the cell surface.

B. Makes it difficult for pathogens to evade immune responses.

C. Increases the degradation of MHC molecule bound to self-

peptide.

D. Protects individuals from autoimmune diseases.