CSIM 1.28 - Cell Co-operation

Question 1

Where are macrophages located?

Answer 1

Resident in tissues

Question 2

How are macrophages activated?

Answer 2

Once barrier is penetrated NK-cells release IFN-Y which directly stimulates macrophages
IFN-Y is also released by Th1 cells

Question 3

How do macrophages recognise pathogens?

Answer 3

PAMP (on pathogen) binds to PRR (on macrophage) - up-regulation of superoxide O2- and lysozyme

Question 4

Which cytokines are secreted by activated macrophages and what are their functions?

Answer 4

IL-1B - activates vascular endothelium and lythocytes
TNF-a - Increases vascular permeability and activates vascular endothelium
IL-6 - lymphocyte activation and increased Ig production
CXCL8 - chemotactic factor for neutrophils/basophils/T-cells
IL-12 - activates NK-cells and promotes Th1 cell differentiation

Question 5

Describe the NK-cells and state their response?

Answer 5

Bone marrow derived 
No Ag specificity 
FCY-RCIII receptor recognises IgG.1 and IgG.3
Kills tumour and virally infected cells
Secretes IFN-Y (activates macrophages)

Question 6

Describe neutrophils and state their response?

Answer 6

Bone marrow derived
Professional killer cells
NOT APC
Attracted by Th-17 cells

Question 7

Which cell helps B-cell immunoglobulin isotype class switching to occur?

Answer 7

CD40 from activated Th2 cell helps initiate class switching

Question 8

Which APC can directly activate CD8 T-cytotoxic cells?

Answer 8

Dendritic cells

Question 9

Name the two ways in which the immune response ceases?

Answer 9

Intrinsic - failure of survival signal maintenance

Extrinsic - activation of death receptors (FAS ligand)

Question 10

Which cytokines activate the coagulation cascade?

Answer 10

IL-1

TNF-a

Question 11

How do macrophages promote new tissue growth and fibroblast proliferation?

Answer 11

Release of fibroblast growth factor and platelet derived growth factor (both mitogens)