Antigen Presentation

Question 1

What cells are constantly inspecting the fragments presented by MHC I complexes?

Answer 1

Killer T cells (Cytotoxic lymphocytes)

Question 2

_____ cells inspect which sends the “don’t kill” signal if a cell is normal.

Answer 2

NK cells

Question 3

What can MHC I present on the cell surface?

Answer 3

Enzymes, Structural Proteins, Proteins encoded by viruses and parasite proteins.

Question 4

Almost every cell in the body expresses ______ molecules.

Answer 4

MHC I

Question 5

Most protein fragments are further broken down into singular ______ _____ for reuse.

Answer 5

Amino Acids

Question 6

Some peptides are brought to the ________ ________ where they are attached to MHC I molecules.

Answer 6

Endoplasmic Reticulum

Question 7

How many MHC I genes are there?

Answer 7

Six; three from mom and three from dad

Question 8

What are the genes for MHC I?

Answer 8

HLA-A, HLA-B, and HLA-C

Question 9

What chromosome are the MHC I genes located on?

Answer 9

Chromosome 6

Question 10

The variability of MHC I molecules allows them to bind to many different kinds of _________.

Answer 10

Peptides

Question 11

T/F: MHC I molecules have a groove in which a peptide must fit.

Answer 11

True

Question 12

How long are most peptides bound to MHC I molecules?

Answer 12

8-11 amino acids long

Question 13

What is the special protein called that protects the binding area of the MHC II?

Answer 13

Invariant Chain Protein

Question 14

What are the four types of antigen presenting cells?

Answer 14

1. ) Activated Dendritic Cells
2. ) Activated Macrophages
3. ) Activated B Cells
4. ) Activated Neutrophils (newly discovered)

Question 15

What is the function of the invariant chain?

Answer 15

Stop other proteins from binding to the MHC II

Question 16

What type of groove exists on the MHC II?

Answer 16

Open groove

Question 17

Most peptides bound to MHC II molecules are how long?

Answer 17

13-25 amino acids long

Question 18

What happens to the ends of the peptide on a MHC II molecule?

Answer 18

They hang over the edges freely.

Question 19

How do dendritic cells initiate the immune response?

Answer 19

They activate virgin T cells

Question 20

What are resting dendritic cells constantly doing?

Answer 20

Sampling the environment (take in and spit back out)

Question 21

What co-stimulator do dendritic cells express?

Answer 21

B7

Question 22

Is a resting dendritic cell a really good antigen presenting cell?

Answer 22

Not really, especially to virgin T cells that require extensive receptor crosslinking and co-stimulation.

Question 23

What activates dendritic cells?

Answer 23

1. ) Chemical signals from cells engaged in battle (TNF and dying cells)
2. ) Recognition of common molecular patterns (each receptor can identify many different pathogens)

Question 24

What are the most common pattern recognition receptors?

Answer 24

Toll Like Receptors

Question 25

Where are TLR located?

Answer 25

On the cell's surface and the inside of the cell.

Question 26

How do ADCs leave the battle ground?

Answer 26

Leaves area through lymphatic system to the nearest lymph node.

Question 27

Prior to leaving the battle ground, ADCs make cytokines that attract ________ into the area, which become dendritic cells and carry new pictures of the battle to the lymph nodes.

Answer 27

Monocytes

Question 28

Do activated dendritic cells kill pathogens?

Answer 28

No, they get others to do the killing

Question 29

Where are activated macrophages located?

Answer 29

Areas of the body exposed to the outside world. Don't travel like ADCs.

Question 30

Function of activated macrophages?

Answer 30

Garbage collectors, Antigen presenting cells, ferocious killers

Question 31

Macrophages only express enough MHC and co-stimulatory molecules to function as APCs after what two events?

Answer 31

1. ) Activaton of battle cytokines | 2. ) Recognizing patterns (TLR)

Question 32

What effect do macrophages have on T cells?

Answer 32

Function to re-stimulate T cells (already activated by dendritic cells but experienced T cells need to be constantly re-stimulated)

Question 33

T/F Virgin B cells make little MHC II and little B7

Answer 33

True

Question 34

How are virgin B cells activated?

Answer 34

By meeting their cognate antigen

Question 35

What are experienced activated B cells able to do?

Answer 35

1. ) Present antigens for helper T cells | 2. ) Concentrate antigen for presentation (displaying both MHC II with antigen and BCR with antigen)

Question 36

T/F: T cells need a threshold number of cross-linked TCRs and MHC IIs to be activated.

Answer 36

True

Question 37

T/F: BCR have a low affinity for their antigen in activated B cells.

Answer 37

False, they have a very high affinity for their antigen.

Question 38

How fast can an activated B cell capture an antigen and present it on the cell surface on a MHC II complex?

Answer 38

30 minutes, very fast

Question 39

T/F: Activated B cells have 100-10,000 fold ability to activate T cells over other APCs?

Answer 39

True