Immunology 4 - Initiation of Acquired Immune Responses

Question 1

What is the only type of antigen T cells can recognise?

Answer 1

Peptide antigens

Question 2

What is a T cell antigen receptor?

Answer 2

A membrane bound protein heterodimer (formed by two different proteins)

Question 3

What present peptide antigens to T cells?

Answer 3

MHC molecules

Question 4

Do B cells require MHC molecules in order to ‘see’ an antigen?

Answer 4

No

Question 5

What does MHC stand for?

Answer 5

Major Histocompatibility Complex

Question 6

What are the features of class 1 MHC molecules?

Answer 6

Expressed on all nucleated cells

Present peptide antigens to CD8+T cells

Question 7

What are CD8+T cells?

Answer 7

Cells that express a CD8 protein

Question 8

What are the features of class 2 MHC molecules?

Answer 8

Expressed only on professional antigen presenting cells (APCs) such as dendritic cells, macrophages and B cells
Present peptide antigen to CD4+T cells

Question 9

What is the main function of dendritic cells?

Answer 9

To process and present antigens on their cell surface to T cells

Question 10

Where are dendritic cells present in large numbers?

Answer 10

Tissues that are in contact with the external environment like the skin

Question 11

Are dendritic cells phagocytic?

Answer 11

Yes

Question 12

What is the effect of pro-inflammatory TNFalpha on dendritic cells?

Answer 12

Stimulates them to mature and increase expression of co-stimulatory molecules

Question 13

What do dendritic cells do after phagocytosing pathogenic antigens?

Answer 13

Break these proteins down into short peptides
Then load them onto class 1 and 2 MHC molecules which are transported to the cell surface

Question 14

What signal do T cells require to be activated?

Answer 14

Co-stimulatory molecules expressed by dendritic cells

Question 15

Why do T cells require a second signal to be activated?

Answer 15

To ensure they only activate in event of infection

Question 16

What are naive T cells called?

Answer 16

CD4+T cells

Question 17

What are proliferating T cells known as?

Answer 17

Th0 cells

Question 18

What types of helper T cells can T cells differentiate into?

Answer 18

Th1
Th2
Tfh
Regulatory T cells

Question 19

What does Tfh stand for?

Answer 19

Folicular helper T cells

Question 20

What is a naive T cell?

Answer 20

One that has never encountered a pathogen

Question 21

What growth factor do antigen activated CD+4 T cells start to secrete and what do they express?

Answer 21

Interleukin 2 (IL-2)
Interleukin 2 receptor

Question 22

What do Th0 cells induce?

Answer 22

Proliferation of CD4+ and CD8+ cells

Question 23

Where do Th1 cells move to from the lymph nodes?

Answer 23

Infected tissues

Question 24

What is the function of Th1 cells?

Answer 24

Secrete pro-inflammatory cytokines to enhance macrophages

Question 25

Where do Tfh cells move to?

Answer 25

B cell zone

Question 26

What is the function of Tfh cells?

Answer 26

Stimulate B cells to clonal proliferate and differentiate into long-lived plasma cells and long-lived memory cells

Question 27

What do antigen-activated CD8+ cells differentiate into?

Answer 27

Cytotoxic T cells/lymphocytes (CTLs)

Question 28

Where do CTLs migrate to?

Answer 28

Site of infection

Question 29

What is the function of CTLs?

Answer 29

To kill virally infected host cells

Question 30

How do CTLs kill virally infected host cells?

Answer 30

Inducing apoptosis