Session 5 Lecture 2

Question 1

What is absolutely needed for adaptive immunity to occur?

Answer 1

Antigen Presenting Cells

Question 2

What are the two types of microbes that the immune system can distinguish between?

Answer 2

Intracellular microbes and extracellular microbes

Question 3

Give an example of an intracellular microbe?

Answer 3

Viruses

Question 4

What information does the APC tell the T cell?

Answer 4

• Host invaded
• Appearance of invader
• Action needed

Question 5

How does the APC deliver information to the T cell?

Answer 5

3 methods - capture, processing and presentation.

Question 6

What is the main job of the APC?

Answer 6

Present the microbe to the cells of the adaptive immune system (usually T cells)

Question 7

Describe the main features of APCs?

Answer 7

• Strategic location
• Pathogen capture
• Diversity in pathogen sensors (PRRs)

Question 8

What are the methods of pathogen capture used by APCs?

Answer 8

Phagocytosis and macropinocytosis

Question 9

What is macropinocytosis?

Answer 9

Uptake of soluble particles (rather than whole microbe)

Question 10

Why is the spleen important in immunity?

Answer 10

It generates B and T cells

Question 11

Where are APCs located?

Answer 11

Skin, mucous membranes, lymphoid organs and blood circulation

Question 12

What are the different types of APCs?

Answer 12

Dendritic cells, langerhans’ cells, macrophages and B cells.

Question 13

What is the location of dendritic cells?

Answer 13

Lymph nodes, mucous membranes and blood.

Question 14

What is the location of langerhan’s cells?

Answer 14

Skin

Question 15

What is the location of macrophages?

Answer 15

Various tissues

Question 16

What is the location of B cells?

Answer 16

Lymphoid tissue

Question 17

What types of APC’s present ONLY to naive T cells?

Answer 17

Dendritic cells and langerhans cells

Question 18

What APC’s present ONLY to effector T cells?

Answer 18

Macrophages

Question 19

What APC’s present to both effector T cells and naive T cells?

Answer 19

B cells

Question 20

What is a naive T cell?

Answer 20

T cell that has not yet encountered antigen presenting cell.

Question 21

What is an effector T cell?

Answer 21

Once a naive T cell has interacted with an APC, it becomes an effector T cell.

Question 22

What does the response of the APC depend on?

Answer 22

PAMPs of the microbes

Question 23

What sort of response do the extracellular microbes cause the APCs to release?

Answer 23

Humoral response

Question 24

What sort of response do the intracellular microbes cause the APCs to release?

Answer 24

Cell dependent immune response

Question 25

What does the humoral immunity consist of?

Answer 25

Antibodies, complement and phagocytosis

Question 26

What does cell-dependent immunity consist of?

Answer 26

Cytotoxic T cells, antibodies and macrophages

Question 27

How do antigen presenting cells actually present the antigens?

Answer 27

This is done by MHC

Question 28

What does MHC stand for?

Answer 28

Major Histocompatibility Complex

Question 29

What is the human MHC called?

Answer 29

HLA - human leukocyte antigen

Question 30

What is MHC?

Answer 30

Set of cell surface proteins essential for the acquired immune system to recognise foreign molecules.

Question 31

What is the main function of MHC?

Answer 31

Bind to antigens derived from pathogens and display them on the cell surface for recognition by appropriate T cells.

Question 32

What are the different types of MHC molecules?

Answer 32

Class I and class II

Question 33

Where are class I molecules found?

Answer 33

All nucleated cells

Question 34

Name the class I molecules genes?

Answer 34

HLA A HLA B HLA C

Question 35

Where are class II molecules found?

Answer 35

Antigen presenting cells therefore found on dendritic cells, macrophages and B cells

Question 36

What are the class II molecules gene?

Answer 36

HLA DR HLA DQ HLA DP

Question 37

What are the key features of MHC class I and class II molecules?

Answer 37

Co-dominant expression, polymorphic genes and peptide presentation.

Question 38

Explain the effects of the co-dominant expression of the MHC?

Answer 38

Both parental genes are expressed therefore increase in the number of different MHC molecules.

Question 39

What is the advantage of having more MHC molecules?

Answer 39

It means more antigens can be presented.

Question 40

Describe the effects of the polymorphic genes of the MHC?

Answer 40

Different alleles amongst different individuals therefore increase presentation of different antigens/microbes

Question 41

Explain the broad specificity of MHC molecules?

Answer 41

Many peptides presented by the same MHC molecules.

Question 42

Describe the structure of a MHC class I molecules?

Answer 42

Alpha chain composed of 3 domains - a1, a2, a3.

Question 43

What is the peptide binding cleft?

Answer 43

Variable region with highly polymorphic residues. This is where the peptide binds.

Question 44

In a MHC class I, what makes up the peptide binding cleft?

Answer 44

Formed by a1 a2 heterodimer

Question 45

Describe the structure of MHC class II molecule?

Answer 45

Formed by two chains, alpha and beta. Each has two domains a1, a2 and b1, b2.

Question 46

What forms the peptide binding cleft in MHC class II?

Answer 46

Formed by the heterodimer of a1 and b1.

Question 47

MHC class I preset epitopes that are recognised by.....

Answer 47

CD8+ T cells

Question 48

MHC class II present epitopes recognised by.....

Answer 48

CD4+ T cells

Question 49

What determines how an antigen will be presented?

Answer 49

Not the nature of the antigen but the route it takes inside the cell.

Question 50

What are the two main routes that an antigen can take?

Answer 50

Endogenous pathway and exogenous pathway.

Question 51

When is the endogenous pathway used?

Answer 51

To present peptide fragments on MHC class 1