The Innate Immune System

Question 1

The immune system actually consists of 2 systems

Answer 1

• The innate immune system

- The adaptive immune system

Question 2

THE INNATE IMMUNE SYSTEM OVERVIEW

Answer 2

• Non-specific responses
• These responses are “hard-wired”
• These responses does not change during the lifespan of the person

Question 3

THE ADAPTIVE IMMUNE SYSTEM OVERVIEW

Answer 3

• Individualised responses that vary from pathogen to pathogen
• Need to be exposed to the pathogen

Question 4

THE INNATE IMMUNE SYSTEM

2 of the major parts of the innate immune system

Answer 4

• Phagocytic cells

- Plasma proteins such as the complement proteins

Question 5

Phagocytes

Answer 5

• White blood cells of the neutrophil and macrophage type
• Due to a combination of signals and changes in the barrier function of the capillary wall: the phagocytes leave the bloodstream and migrate to the site of infection
• They engulf infectious agents (but also dead and dying cells and cell debris) and this leads to destruction of the foreign material

Question 6

Cytokines

Answer 6

• Locally released protein factors which regulates the activity of cells
• The are secreted by cells of the immune systems as well as other local non-immune cells types
• All of the cells involved in the immune response communicate via cytokines
• Cytokines stimulate or inhibit, the activity of innate and adaptive immune systems

Question 7

THE COMPLEMENT SYSTEM

Answer 7

• A set of plasma proteins that circulate in their inactive form
• Each protein is named C plus a number related to the order that they were discovered
• Several possible starting points

When activated there is a cascade of activation

• The the first protein activates the second and so on…
• Activation can involve splitting the inactive protein into fragments
• Sometime the activated components combine together in a complex

Question 8

FUNCTIONS OF THE COMPLEMENT SYSTEM

Answer 8

• The formation of a protein complex (the Membrane Attack Complex) on the surface of the pathogen which causes membrane lysis
• Formation of protein fragments which can stimulate other immune responses for example :
• Opsonization: coating a cell in molecules to improve the chance that is phagocytosed by immune cells
• Chemotaxis: Some complement fragments will attract immune cells out of the circulation and into the site of infection or cell damage