Session 10

Question 0

What are the humoral components of the innate immune system?

Answer 0

• Transferrin and Lactoferrin: deprive microorganisms of iron
• Interferons: inhibit viral replication
• Lysosome: breaks down peptidoglycan in bacterial cell walls
• Antimicrobial peptides
• Fibronectin: opsonises bacteria and promotes their phagocytosis
• Complement: causes destruction of microorganisms directly or with the help of phagocytic cells
• TNF-a: suppresses viral replication and activates phagocytes

Question 1

What types of immune system are there and what are they composed of?

Answer 1

• Innate
• Adaptive
• Both are broken down into humoral and cellular

Question 2

What are the cellular component of the innate immune system?

Answer 2

• Macrophages and Monocytes: phagocytosis and antigen presentation to lymphocytes; phagocytosis is enhanced by the coating of antibodies or complement to render it recognisable as foreign (opsonisation)
• 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 tumours

Question 3

What are the humoral components of the adaptive immune system?

Answer 3

• Cytokines: promote differentiation and proliferation of lymphocytes
• Perforin: released by T killer cells and destroys cell walls
• Antibodies: protect host cell by neutralisation (prevents binding to epithelia, opsonisation and complement activation (enhances opsonisation and lysis)

Question 4

What are the cellular components of the adaptive immune system?

Answer 4

• T cells:
  ~ T helper: activated when CD4 binds to a specific antigen on the MHC/antigen complex of an antigen presenting cell, once activated it clones itself to form active T-helper cells and T-memory cells
  ~ T killer: releases Perforin when the cell is already infected
• B cells: divide to form plasma cells and memory cells when activated by T-helper cells and releases cytokines, plasma cells produce specific immunoglobulin for non-self antigens

Question 5

What are the main differences between the innate and adaptive immune system?

Answer 5

• Innate: - Adaptive:
  ~ present from birth ~ arises from exposure to
  microorganisms
  ~ non-specific ~ specific pathogen
  immunity
  ~ not enhanced by second ~ enhanced by second
  exposure exposure
  ~ no memory ~ acquires memory
  (memory cells)
  ~ poorly effective without ~ poorly effective without
  adaptive response innate immunity

Question 6

What is the difference between the speed of response between the innate and adaptive responses?

Answer 6

• Innate: quicker; doesn’t last long after the infection
• Adaptive: slower to respond; lasts much longer after infection
• Both work together to fight infection effectively