Immunology

Question 1

What does innate immunity refer to?

Answer 1

Innate immunity refers to antigen-nonspecific defence mechanisms that a host uses immediately or within several hours after exposure to an antigen

Question 2

Are we born with innate immunity?

Answer 2

This is the immunity one is born with and is the initial response by the body to eliminate microbes and prevent infection

Question 3

What is innate body defence also known as?

Answer 3

The acute phase response is an innate body defence seen during acute illnesses and involves the change in plasma concentrations of certain blood proteins

Question 4

Acute phase response protein?

Answer 4

These proteins are called acute phase proteins

Question 5

Where are acute phase proteins (APPs) produced?

Answer 5

A group of proteins, produced by cells in the liver and promote inflammation, activate the complement cascade, and stimulate chemotaxis of phagocytes

Question 6

What groups can APPs be divided into?

Answer 6

Positive and negative APPs

Question 7

What are positive APPs responsible for?

Answer 7

Positive APP concentration increases during inflammation. Positive APPs act as inhibitors or destroyers of micro-organism growth as well as providing feedback on immune function

Question 8

What are negative APPs responsible for?

Answer 8

Negative APP concentration decreases during inflammation

Question 9

Acute phase response outcomes:

Answer 9

• The rise of APP part of wider response
• Includes fever, leucocytosis, increased immune reactivity
• Mediated by cytokines and TNF (tumour necrosis factor) released from macrophages
• In some chronic diseases can have periodic or continuous evidence of the acute phase response

Question 10

Cytokine mediation

Answer 10

• Most notable of the cytokines that stimulate the APR are IL-1, IL-6, IL-8 and TNF.
• Interleukins released by white blood cells usually CD4+ T lymphocytes as well as monocytes and macrophages
• TNF – Tumour Necrosis Factor. Produced by macrophages and amongst other functions works to stimulate the production of C- Reactive Protein (CRP)
• Released in response to presence of bacterial products such as lipopolysaccharide.

Question 11

Example of APP: CRP (C- Reactive Protein)

Answer 11

• Level increases 50,000 fold in response to increased production of IL-6 by macrophages
• Binds to phosphocholine receptor on bacteria
• Assists in complement binding to cell surface via C1q molecule
• Also helps to induce phagocytosis by binding to receptor (opsonisation)

Question 12

Example of APP: Serum Amyloid A

Answer 12

• Produced in the liver
• Early AP reactant
• Role is to attract immune cells to site of infection

Question 13

Example of APP: α1-antitrypsin

Answer 13

• Serine Protease inhibitor (SERPIN)
• Inhibits elastase produced by granules in neutrophil
• Stops breakdown of elastic tissue

Question 14

Example of APP: Ferritin

Answer 14

• Storage protein for iron
• Produced to inhibit iron uptake by bacteria

Question 15

Example of APP: Haptoglobin

Answer 15

• Binds to haemoglobin
• Also reducing iron utilisation by bacteria

Question 16

Example of APP: Ceruloplasmin

Answer 16

• Copper dependent protein that has role in oxidising iron thereby inhibiting bacterial uptake

Question 17

Example of APP: Albumin

Answer 17

• Most common protein in serum
• Has role in molecular transport and providing colloid osmotic pressure
• Less albumin thought to inhibit bacterial growth

Question 18

Example of APP: Transferrin

Answer 18

• Major iron transport protein
• Limits amount of iron for bacterial growth