Effector function

Question 1

Define the term autocrine

Answer 1

cell produces signals that act on the same cell

Question 2

Define the term paracrine

Answer 2

cell signalling to adjacent

Question 3

Define the term endocrine

Answer 3

cell signalling through hormones in the bloodstream

Question 4

What is the structural difference between CC and CXC

Answer 4

CC: two adjacent cysteine residues near amino terminus
CXC: equivalent cysteine residues are separated by single amino acid

Question 5

Describe the JAK-STAT pathway [10]

Answer 5

-cytokine binds to receptor
- dimerisation of receptor
-brings JAKs together
- JAKs activate each other
- phopshorlisation of the receptor
-STAT binds to phosphorylated receptor
-becomes phosphorylates itself
- phorsphorylated STATs form dimers
-move to nucleus
-initate gene transcription

Question 6

What is the role of E-selectin [4]

Answer 6

-found on the walls of veins
- adhesion to S-LEX
- slows cells down
- so that they can survey the endothelial tissue for infection

Question 7

What are the four key steps to neutrophil extravasation

Answer 7

rolling adhesion
tight binding
diapedesis
migration

Question 8

Describe the process of phagocyte recruitment in the veins [7]

Answer 8

• IL8 (chemokine) exits tissue
• activates LFA-1
  -leads to tight binding to endothelial
• causes cell to stop
• changes to endothelial barrier
  -allows phagocyte to pass through
• reach the area of infection following the chemokine gradient

Question 9

What is the difference between M1 and M2

Answer 9

M1 is primarily inflammatory
M2 are primarily anti-inflammatory

Question 10

What is the difference between type I and type II IF

Answer 10

type I: mainly antiviral
type II: activated by macrophages

Question 11

Describe the process that causes antiviral state

Answer 11

• cell recognises virus in cytosol
  -activates JACK-STAT pathway
• gene expression for the 3 mechanisms

Question 12

What are the 3 mechanisms that lead to an antiviral state

Answer 12

• PKR: inhibition of viral protein synthesis
• Mx GTPase: inhibition of viral gene expression
• oligosynthase: degredation of viral DNA

Question 13

Describe the acute phase response [5]

Answer 13

• bacteria induces macrophages to produce IL-6 in the liver
  -acts on hepatocytes to release acute phase proteins (c reactive proteins)
• C reactive proteins bind to phosphocholine on bacterial surfaces
• acts as opsonin
• activates compliment pathway

Question 14

What is the role of ITAM

Answer 14

activate NK cells

Question 15

Describe the role of perforin and granzymes in NK killing

Answer 15

• granzyme/perforin released form NK cell
• perforin forms pore
  -so that granzyme can enter the cell
  -activates caspases
• leads to cascade independent death (apoptosis)

Question 16

Describe how TRIAL leads to cell death

[4]

Answer 16

• found on NK cells
  -binds to TRIAL receptor on target cells
  -activates caspases
• leads to apoptosis

Question 17

What is the role of SOCS

Answer 17

• suppress cytokine signalling
• inhibits JAK STAT pathway