Immunity to bacteria Flashcards
What are PAMPs? What do they cause?
Pathogen-associated molecular patterns
Molecules found only on pathogens
Induce immune response by host cells - cytokine production and antigen presentation
What are toll-like receptors? Which cells have them?
Receptors that recognise PAMPs on pathogens
Monocytes/macrophages, mast cells, B cells
What are the innate immune responses to bacteria?
Acute phase proteins Complement system Phagocytosis by neutrophils Macrophage activation Detection of PAMPs by TLRs
Which cells produce cytokines? What do they do?
Macrophages
Attract other cells, induce fluid exudate from blood (oedema)
How can bacteria avoid phagocytosis?
Bacterial capsule
Protein A (on staph aureus)
M protein - blocks complement
How can bacteria survive inside phagocytes?
Avoid phagolysozomes
Lyse phagolysozomes
Survive in phagosomes (resistant to degradative enzymes or inhibit them)
Is acquired immunity to bacteria mainly cell mediated or humoral? What cell mediates this?
Humoral - antibody mediated
(Unless intracellular)
TH2
How do antibodies evade the acquired immune system?
Formation of biofilms
Mimic host antigens to look like self
Antigenic variation
IgA protease enzyme - clears antibodies in mucosal secretions
What is the difference between bacterial endotoxins and exotoxins?
Endotoxins - membrane bound
Exotoxins - secreted
What is endotoxic shock?
Excessive release of cytokines triggered by lipopolysaccharides
In response to bacterial endotoxins
What are the symptoms of endotoxic shock?
Increased vascular permeability
Loss of fluid in tissues
Hypovolaemia
Circulatory collapse in gut
What are superantigens?
T- cell activators produced by bacteria to induce ineffective host immunity
(hyperstimulate immune system)
How do super antigens over stimulate the immune system? What do they cause?
Cause overreaction
Fever, cause, diarrhoea, vomiting, dehydration and circulatory collase
Cause of toxic shock syndrome (staph aureus and streptococcus pyogenes)
