Cell-Mediated Immunity

Question 1

TCR complex: First signal

Answer 1

TCR binds antigen, CD3/zeta chain generate signal

Question 2

TCR complex: Second signal

Answer 2

CD28 (T-cell) binds CD80/86 (APC)

Question 3

TCR complex: Third signal

Answer 3

Cytokines (depends on infection)

Question 4

What stabilizes the interaction of APC with TCR?

Answer 4

LFA-1 binds ICAM-1

Question 5

T-cell accessory molecule used for signal transduction by TCR complex

Answer 5

CD3 / zeta chains

Question 6

Function of CD4 and its ligand

Answer 6

Function: Signal transduction
Ligand: Class II MHC on APCs

Question 7

Function of CD8 and its ligand

Answer 7

Function: Signal transduction
Ligand: Class I MHC on APCs, Class I target cells

Question 8

Function of CD28 and its ligand

Answer 8

Function: CO-STIMULATION
Ligand: CD80/86 on APCs

Question 9

Function of CTLA-4 and its ligand

Answer 9

Function: Signal transduction (negative regulation)
Ligand: CD80/86 on APCs

Question 10

Function of LFA-1 and its ligand

Answer 10

Function: Adhesion
Ligand: ICAM-1 on APCs and endothelial cells

Question 11

What secretes IFN-gamma and IL-12 for Th1 induction?

Answer 11

Dendritic cells

Question 12

What are the three functions of IFN-gamma?

Answer 12

1. Stimulates complement and Fc receptor-binding IgG subclasses (activates B cells in the lymph nodes to release IgG)
2. Macrophage activation (classical pathway)
3. Recruits monocytes

Question 13

Actions of activated macrophages

Answer 13

1. Secretion of TNF, IL-1, IL-12, chemokines
2. Increased expression of MHC, CD80/86
3. Killing of phagocytosed bacteria

Question 14

What interaction is required for macrophages to be activated?

Answer 14

CD40L on T-cell binding CD40 on macrophage

Question 15

What are the functions of the cytokines produced by activated Th1?

Answer 15

TNF alpha –> endothelial cells –> inflammation
IL-2 –> T cell differentiation
IFN-gamma –> macrophage activation –> intracellular pathogens

Question 16

What are the functions of the cytokines produced by activated Th2?

Answer 16

IL-4 –> IgE –> allergic reactions
IL-5 –> basophils –> helminths
IL-13 –> same as 4

Question 17

What are the functions of the cytokines produced by activated Th17?

Answer 17

IL-17 / IL-22 –> neutrophils –> extracellular pathogens

Question 18

Which cytokine is imperative for T cell differentiation/proliferation?

Answer 18

IL-2

Question 19

Where are T cells activated?

Answer 19

Paracortex of lymph nodes

PALS of spleen

Question 20

What is cross presentation?

Answer 20

Dendritic cell can phagocytize a cell (usually presented on MHC II), but still present to CD8 cell via MHC I

Question 21

What granules do CD8 cells release? What are their functions?

Answer 21

Granzyme
Perforin

Perforin perforates the pathogen membrane, then releases granzymes to induce apoptosis

Question 22

Which cytokine supports proliferation and differentiation of developing lymphocytes in the primary lymphoid tissue?

Answer 22

IL-7

Question 23

What do macrophages produce to promote Th1 differentiation and inflammation?

Answer 23

TNF-alpha
IL-1
IL-12

Question 24

Which immune cells are responsible for the formation of a granuloma?

Answer 24

Th1 cells

Macrophages