E-Learning Innate Immunity

Question 1

What recognises abnormal antigens in the innate system? [2]

Answer 1

Pattern Recognition Receptors e.g TLRs detect

• PAMPS = detect pathogens antigens e.g. Lipopolysaccharide
• DAMPS = Detect damaged cell antigens e.g. DNA

Question 2

What triggers inflammation? [1]

What are the 2 important events in the start of inflammation? [2]

Answer 2

PRRs detect PAMPS/DAMPS

• -> Immune cells e.g. macrophages release cytokines (IL-1 & TNF-alpha)
• -> Increased vascular permeability, vascular adhesion molecules and chemokines

Question 3

Example of a Vascular Adhesion Molecule released in inflammation?

Answer 3

Selectin

Question 4

How do WCs escape into inflamed tissues?

Answer 4

Leukocyte Extravasation (aka Diapedesis)

Question 5

What causes the cardinal signs of inflammation (Calor, Rubor, Dolor, tumor)?

Answer 5

Histamine & bradykinin

Question 6

How are immune cells recruited? [2]

Answer 6

Profesional APCs present antigens to them via MHC2 –> T cell recruitment

Question 7

CD8 T cells and NK cells both use perforin induced apoptosis to destroy invaders.
What’s the difference between CD8 T cells and NK cells? [3]

Answer 7

NK cells are:

• Faster
• Don’t need antigen priming
• Lack memory

Question 8

What special cell type can NK cells target?

Answer 8

Infected/damaged cells that lack an MHC1

Question 9

How does NK cell activation work?

Answer 9

They have both activatory and inhibitory receptors (attach to host MHC1).

to be activated the +ve signal must outweight the -ve.

Activatory receptors also respond to cells lacking an MHC1, hence why NK cells can attack them,

Question 10

What do NK cells do? [3]

Answer 10

1) Release perforin & granzymes –> Apoptosis
2) Release IFN-gamma –> Macrophages
3) Release TNF-alpha –> Enhanced NK cell cytotoxicity

Question 11

Describe the process of phagocytosis? [5]

Answer 11

Moves towards infection by chemotaxis

• -> Ingests microbe into phagosome
• -> Phagosome fuses with lysosome to form phagolysosome
• -> Microbe is digested
• -> Waste material formed into residual body and discarded

Question 12

How does opsonisation hasten phagocytosis? [2]

Answer 12

Reduces -ve charge

And increases binding sites

Question 13

How does the Lectin pathway work?

Answer 13

Circulating Lectin binds to polysaccharides on the pathogen surface –> Picked up by complement

Question 14

How does the Alternative Pathway work?

Answer 14

Complement proteins bind to the pathogen surface directly. Without lectin or Abs

Question 15

How is the complement cascade started? [3]

Answer 15

Activation of C3 Convertase

• -> C3a (Recruits immune cells and mast cells)
• -> C3b (Opsonin, precursor to C5 and helps clear immune complexes)

Question 16

What complement proteins form the MAC? [5]

Answer 16

C5b, 6, 7, 8 & 9

Question 17

What does the MAC do? [3]

Answer 17

Punches a pore in the target cell membrane allowing H2O to flow in

• -> Osmotic rupture
• -> Cell Death