Antigens and Antigen Processing

Antigen

a microbe or other foreign substance which induces an immune response in the body

Immunogen

antogen capable of triggering an immune response

Immunogenicity

relative ability to induce an immune response

Epitope

small site on a large antigenic molecule to which the antigen receptor attaches

Hapten

tiny molecule that can not trigger an immune response by itself

Carrier

large molecule to which a happen can be linked to make the happen immunogenic

True or False: A pathogen can have thousands of different epitopes.

TRUE

True ot False: All epitopes on a pathogen or immunogenic

FALSE

Give an example of a hapten

Penicillin does not illicit an immune response unless it is bound to albumin

What are two categories of factors that affect immunogenicity? List their subexamples.

• Nature of the immunogen

  • Foreigness

  • Molecular size

  • Chemical composition and complexity

  • Degradability

• Biological System

  • Genotype

  • Immunogen dosage and route of administration

  • Adjuvant

True or False: Immunogenicity is directly proportional to foreigness

TRUE

True or False: antigens must be above a minimum size in order to start an immune respinse

TRUE

What things are readily degraded (immunogenic)

Proteins and polysaccharides

What things are poorly degraded (not immunogenic)

nucleic acids and lipids

What are immunogens degraded by?

Antigen presenting cells

T-cell dependent antigens steps

1. Antigen presenting cell recognizes and processes antigen

2. Presents antigenic epitope to a helper T cell

3. Helper T cell produces cytokines to stimulate other immune cells

4. Immune cells colon ally expand to form effector and memory cells

T-cell independent antigens are characterized by the production of ______ and does not produce ________ cells.

IgM; memory B

How do antigen presenting cells display antigen fragments?

they use an MHC molecule on their surface

True or False: Antigens dont need to be processed and presented with an MHC molecule to be recognized by T cells.

TRUE

What are the professional antigen presenting cells?

Dendritic cells, macrophages, B cells

True or False: ONLY dendritic cells, macrophages, and B cells can act as antigen presenting cells

FALSE - others just not as obvious

What is the only antigen presenting cell that can activate naive T cells?

Dendritic cells

What is the primary function of dendritic cells?

immune surveillance and antigen processing and presentation

For dendritic cells, where does antigen presentation occur?

Lymphoid organs

How do dendritic cells mature?

when exposedd to inflammatory mediators, bacterial products, cytokines, or DAMPs

Where are immature dendritic cells found?

peripheral tissues

How does the dendritic cell ensure the most efficient and correct response is done?

they commit to the immune response based on the nature of the pathogen

Pinocytosis

fluid phase uptake with the capture of small particles and ECF through small membrane invaginations

• all cells do this

Macropinocytosis

large scale, pinocytosis, characteristic dendritic cells

What type of pathogen does MHC II do?

extracellular

What type of pathogen does MHC I do?

intracellular pathogens

What type of naive T cell is activated with MHC I?

Cytotoxic T cells

What type of naive T cell is activated with MHC II?

Helper T cells

MHC I uses a ______

proteasome