Macrophage Interactions Flashcards
What are methods used by extracellular pathogens to avoid being degraded by phagocytes?
- Avoid recognition by phagocytes
- inhibit engulfment/inflammatory response
- produce capsule to prevent phagocytosis/hide antigens
- disable the phagocyte by toxins
What are strategies used by intracellular pathogens?
- inhibit phagosome function
- survive inside phagosomes resisting degradation
- escape from the phagosome
What are ways in which phagocytes recognize microbes?
They recognize peptidoglycan layer, flagellum, LPS, and outer membrane via TLR/PRP. Can also bind to immune system components like complement and Fc regions
– Capsules Hide the Antigens from Phagocytes –
How do phagocytes uptake pathogens?
Normally by phagocytosis, spiraling and looping (Legionella). Passive Process.
What are different methods pathogens enter non-phagocytotic cells?
Trigger Method - major membrane remodeling - Salmonella
Zipper Method - minor membrane disruption - Listeria
–both require bacterial proteins being injected–
How can bacteria alter maturation of the phagosome?
- survive and replicate inside of it
- escape and replicate in cytosol
RMSF, Shigella, E.Coli, and Listeria - Modulate endocytic pathway
Mycobacterium and Salmonella
-Alternative Trafficking
Legionella, Brucella, and Chlamydia
What are the two methods of killing by lysosomes?
Oxygen-independent Killing: Low pH and defensins
Oxygen-dependent killing: iNOS, NADPH Oxidase, using free radicals to kill pathogens.
What are benefits of macrophages internalizing bacteria?
- initiates immune response and production of cytokines
- mediates recruitment of lymphocytes
- increases vascular permeability
What are adverse effects of activation of innate immune system?
-chronic infections can cause long term tissue damage, autoimmunity, can facilitate the spread of bacteria.
