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22 Cards in this Set

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