Immunology

Question 1

Good bacteria

Answer 1

• out number our own cells >10 to 1
• aid in digestion, synthesis of vitamins and enzymes not
  produced by the human body
• prevent colonisation of pathogenic bacteria
• some are opportunistic pathogens
• can cause disease if exposed to a usually sterile site or
  the host’s resistance is low

Question 2

Bad bacteria

Answer 2

• pathogenic organisms
• different modes of transmission:
  + person to person
  + food
  + water
  + insects
  + fomites

Question 3

Primary defence functions of the immune system

Answer 3

• prevent establishment of infection
• recognise infections
• remove established infections

Question 4

Strategies of the host to protect itself

Answer 4

1. anatomic and physiologic barriers
   
   • intact epithelial surfaces
   • mucus
   • additional mechanical movements to remove invaders
   • many body secretions contain bactericidal
     components
   • low stomach pH
   • microbiota
2. Innate Immunity
   
   • recognises and responds to molecules expressed by
     groups of related microbes
   • limited diversity; coded in the germ line
   • no memory
   • non-reactive to itself
   • blood proteins: complement, others
   • cells: phagocytes natural killer cells
3. Adaptive immunity
   
   • recognises and responds to microbial and non-
     microbial antigens
   • very large diversity; receptors are formed by
     recombination of gene segments
   • has a memory
   • non-reactive to itself
   • blood proteins: antibodies
   • cells: lymphocytes

Question 5

Immune cells

Answer 5

• phagocytes
• neutrophil
• other granulocytes
  + eosinophils
  + basophils
  + mast cells
• macrophage
• antigen presenting cells (APCs)
• dendritic cells
• lymphocytes
• natural killer cells (NK cells)

Question 6

Immunological tissue

Answer 6

- primary lymphoid organs
   \+ bone marrow
   \+ thymus
- secondary lymphoid organs
   \+ lymph nodes
   \+ spleen 
   \+ mucosal-associated lymphoid tissue (MALT)

Question 7

Response to infection

Answer 7

• once inside the body, infectious agents spread to infect new cells by passing through the body fluids or tissues.
• infections can be:
  + extracellular (does not invade host cells)
  + intracellular (invades host cells to reproduce)
• inflammation
  + phagocytosis
  + complement activation
• antiviral defense
  + interferons
  + NK cells

Question 8

5 classes of antibody

Answer 8

• IgM
  + original BCR structure on naive B cells
  + effective agglutinates particulate antigens; bacterial
  opsonisation
• IgG
  + antibody-dependent cell cytotoxicity, antiviral, toxin
  neutralisation
• IgA
  + high concentration in mucosa and epithelium.
  Antiviral, toxin neutralisation
• IgE
  + binds to mast cells and basophils
  + mediation of allergic response, effective against
  parasitic worms
• IgD
  + found on surface of mature B cells, signalling via
  cytoplasmic tail