Immunity

• Pathogen - any organism which can cause diseases
• Immune/defense system

  • Defends the body against any foreign

  molecule

  • Aims to limit if not prevent infections
• Innate immunity

  • Offers primary defense in all animals
  • Sets the stage for adaptive immunity
• Adaptive/acquired immunity

  • Unique to vertebrates
• Innate/Adaptive Immunity

  A) small

  B) vast

  C) specific

  D) specific

  E) broad

  F) specific

  G) rapid

  H) slower

  I) No memory

  J) With Memory

  K) Birth

  L) after

  M) vaccination

  N) delayed

  O) acute

  P) Barrier

  Q) Internal

  R) Humoral

  S) cell-mediated

  
• Innate immunity of Poriferans

  • Highly exposed to viruses and bacteria

  -Feed thru filter feeding

  • Produce secondary metabolites

  -ex. antibiotic compounds

  -kill/prevent bacterial/viral growth inside their body
• Innate immunity of Cnidarians

  • Most have nematocysts

  -stinging cells which inject toxins to a prey/predator

  • produce a variety of toxins
  • some produce antimicrobial compounds

  -prevent microbial growth
• Innate immunity of Flatworms

  • Phagocytic cells which engulfs microbes absorbed with food
  • Produce perforin

  -induces lysis

  -destroys microbial cell membranes

  A) Cytotoxic T

  B) Perforin

  C) apoptosis

  
• Innate immunity of Helminths:

  Annelids – segmented worms

  • Antimicrobial compounds
  • Phagocytic abilities of their cell
  • Body fluids have antimicrobial and clotting ability
• Innate immunity of Mollusks

  • Anatomic barrier defense

  -1st line of defense: shells

  • Phagocytic cells

  -Ex. Hemocytes circulate in body fluids

  -->Engulf & destroy small invaders

  • Body fluids

  -Secretes toxic enzymes & compounds (ex. Lysozymes &

  NO)

  --> Kill invading pathogen
• Innate immunity of Arthropods - classified as either barrier defense OR internal immune defense
• barrier defense of Arthropods

  • 1st line of defense – defend against outside invaders
  • Exoskeleton – made of chitin
  • Chitin lining in digestive tract

  --->Protect against pathogens ingested with food

  • Lysozyme

  --->breaks down bacterial cell walls

  --->Protects insect digestive system
• internal immune defense

  • 2nd line of defense
  • Immune cells produce a set of recognition proteins
  • Binds to a molecule common to a broad class of pathogen

  --->Found in fungal & bacterial pathogens but not in animal cells

  --->Molecules function as identity tags and recognized as pathogens

  • proteins bind to a pathogen molecule  innate immune

  response is activated
• Innate immunity of Arthropods:

  Hemocytes

  • Major immune cells of insects
  • Mechanisms on killing/neutralizing pathogens

  --->Phagocytosis

  --->Produce defense molecule trapping large pathogen

  --->Release antimicrobial peptides

  -Inactivate/kill fungi & bacteria by disrupting their

  plasma membrane