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22 Cards in this Set
- Front
- Back
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what can happen as a consequence of too much host responses on extracellular bacteria?
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Inflammation
septic shock LPS Superantigens |
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What happens when there is too much LPS
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Cytokine stom
results in septic shock hypoglycemia, cardiovascular problems |
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Too much superantigens?
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superantigen binds to Vbeta region and triggers excessive proliferation which then dies
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Mechanims extracellular bacteria evade immune response
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1. antigenic vairation - rearrange proteins
2. inhibit complement activation 3. resist phagocytosis 4. scaveging of reactive oxygen intermediates |
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mechamisms intracellular bacteria evade immune response
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1. inhibi phagolysosome formation
2. inactivation of reactive oxygen and nitrogen 3. disruption of phagosome membrane and escape into cytplasm |
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Intracellular bacteria immunity
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uses phagocytes (neutrophils and macrophages) for phagocytosis --> activates IL12 which activated NK cells and that activates IFN gamma which induces phagocytosis by macrophages
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what is the major protective immune response agains intracellylar bacteria
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T cell mediated immunity
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IFNgamma and IL12 Knockout Mouse experiment
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IFN gamma knockout results in faster infection. So it is more trivial in immune response
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What also helps in defense against intracellular bacteria
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CD4+ T cells and CD8+ CTLs
* the correct recognition with MHC gives the kiss of death |
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CD4+ T cell defence
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TH1 cells - activate phagocytes to kill microbes
TH2 cells - inhibit macrophage activation --> tolerance |
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What happens when there is TOO much macrophage activation in response to intracellular microbes?
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Tissue injury --> granulomatous inflammation
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what are the principal mediators of innate immunity in fungi
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neutrophils and macrophages
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Neutrophils as fugi mediator
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secrete fungicidal substances such as reactive oxygen and lysosomal enzymes, and phagocytose fungi
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Cryptococcus neoformans
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inhibit production of TNF and IL 12
stimulate IL10 which inhibits macrophage activation |
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Candida albican
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produce proteases SAP that inactivate antimicrobial peptides (needed in defense)
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Th17
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T cells that produce IL17
it is involved in immune response to fungi |
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Mechanism of innate immunity against viruses
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inhibit infection by type I IFNs and NK cell mediated killing
Downregulated MHC class I RNAseL degrades viral RNA |
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Mechanism of Adaptive immunity against viruses
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production of antibodies --> blocks entry into host (protective mechamism)
CTL recognize virus and kills them (clearing mechanism) |
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which viruses are uneradicable
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latent and integrated viruses.
ex. HIV |
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How do viruses evade adaptive immunity?
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- alter antigens
- inhibit class I MHC - inhibit immune response - failed CTL responses - infecting or killing immunocompetent cells |
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Immune respose to helminthic parasites
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similar to mechanims for extracellular bacteria
except it forms TH2 cell response Mast cell produces histamine which is toxic for helminthe |
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what pathogens makes a good vaccine
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- cause illness
- one serotype - antibody blocks infection - not oncogenic - heat stable |
