Innate Community

Question 1

Define Innate Immunity. Provide examples.

Answer 1

• Immunity that is present at birth and lasts a person’s entire life - first response of the body’s immune system to a harmful foreign substance
  Ie. Cough reflex, Enzymes in tears and skin oils, Mucus, Skin, Stomach acid

NOTE: cell function BESIDES B cell and T cell ie. macrophage, dendritic cell

Question 2

Mucins & Selectins

Answer 2

• glycoproteins on endothelial and immune cells
• constantly expressed and activated
• weak binding to one another

Question 3

Describe Mucins

Answer 3

On all cells ie. wbc, endothelial cells

Question 4

Examples of selectins

Answer 4

L-selectin: WBCs

E-selectin, P-selectin: endothelial cells

Question 5

Describe Integrins

Answer 5

• inactive proteins in α and β subunits that help cells attach to each other and extracellular matrix
• must be activated to dimerize

Question 6

Example of Integrins

Answer 6

• CD11
• CD18

Question 7

Describe Ig Superfamily CAMs

Answer 7

• bind integrin dimers
• facilitates tight binding

CAM = cellular adhesion molecules

Question 8

Outline Leukocyte Rolling and Extravasion

Answer 8

1. Rolling:
- weak binding along blood vessel = marginal pool
- mucin on neutrophil bind P-selectin and E-selectin on endothelial cell
- L-selectin on neutrophil bind to mucin on endothelial cell
2. Extravasion:
- Integrin subunits α (CD11) and β (CD18) join in response to cytokines = LFA-1
- LFA-1 bind ICAM on endothelial cells = tight binding = stops rolling, and neutrophil squeezes through endothelial cells

Question 9

Describe TNF

Answer 9

Tumor Necrosis Factor:
- pro-inflammatory (chemoattractant, increases adhesion, primes macrophages)
- induces fever
- activates immune cells through TNRF1
- activates endothelial cell proliferation (wound healing)
- induce apoptosis

Question 10

Describe IFNy

Answer 10

• secreted by Th1, T cytotoxic, NK, macrophages
• activates immune cells (expresses MHC I/II, CAMs, receptors, lysosomes/ NOS, anti-viral)

NOS = nitric oxidative species

Question 11

How does the innate immune system defend against viruses ?

Answer 11

• phagocytosis: by macrophages and neutrophils
• complement: tags for opsonization via C3, lyses enveloped viruses via MAC
• NK cells produce IFNy; direct killing if MHC I on cells is reduced by viruses trying to avoid expression of viral particles