ToB S11 - Innate & Adaptive Immunity

Question 1

Define innate immunity

Answer 1

The non-specific immunity you are born with that comes into play immediately or within hours of an antigens appearance in the body

Question 2

Define adaptive immunity

Answer 2

The antigen-specific response

Question 3

Outline the differences between the innate and adaptive immunity

Answer 3

Innate

• Present from birth
• Non-specific
• Not enhanced by second exposure
• No memory
• Poorly effective without adaptive response

Adaptive

• Arises from exposure to microorganisms
• Specific pathogen immunity
• Enhanced by second exposure
• Acquires memory (memory cells)
• Poorly effective without the innate immune system

Question 4

Outline complement

Answer 4

A cascade of blood soluble proteins that lead to the opsonisation of bacteria or the direct lysis of it by formation of the MAC complex

Question 5

What are the humoral components of the innate immune system?

Answer 5

• Transferrin and lactoferrin - deprive microorganisms of iron
• Interferons - inhabit viral replication
• Lysozyme - Breaks down peptidoglycan in the bacterial cell wall
• Fibronectin - opsonises bacteria and promotes their phagocytosis
• Complement - Causes destruction of microorganisms directly or with the help of phagocytic cells
• TNF-α - Supresses viral replication and activates phagocytes

Question 6

What are the cellular components of the innate immune system?

Answer 6

• Macrophages and monocytes - Phagocytosis and antigen presentation to lymphocytes
• Neutrophils - phagocytic and anti-bacterial
• Eosinophils - anti-parasite and allergic response
• Basophils and mast cells - allergic response

Natural killer cells - recognise and kill abnormal cells Eg tumour cells

Question 7

What are the humoral components of the adaptive immune system?

Answer 7

• Cytokine - promote the differentiation and proliferation of lymphocytes
• Perforin - Released by T killer cells that destroy cell walls
• Antibodies - Protect host by neutralisation (prevents binding to epithelia), opsonisation and complement activation

Question 8

What are the cellular components of the adaptive immune response?

Answer 8

T Cell - T helper and T killer cells

T helper - Becomes activated when the CD4 binds to a specific antigen on the MHC/antigen complex of an APC (Antigen presenting cell). Once activated, it clones itself to form active T-helper cells and T-memory cells

T-Killer cells - release perforin when the cell is already infected

B-cell - divide to form plasma cells and memory cells when activated by T-helper cells and release cytokines. Plasma cells produce specific immunoglobulin for non-self antigen