Innate cells Flashcards
What are the different phagocytes of the innate immune system?
Neutrophils, macrophages and dendritic cells
What are the different lymphocytes of the innate immune system?
Natural killer cells
Distinguish phagocytes and lymphocytes in their role in the innate immune system.
Phagocytes kill off extracellular pathogens
Lymphocytes kill off intracellular pathogens
What process do phagocytes used to destroy pathogens?
Phagocytosis
What process do lymphocytes of the innate immune system use to destroy pathogens?
Initiate apoptosis in infected cells
Describe, briefly, the process of phagocytosis.
Phagocyte binds to a pathogen, and endocytoses it into a vesicle, called a phagosome,
The phagosome then fuses with the lysosome, which dumps acid and enzyme contents to cause degradation of the pathogen
What does the lysosome contain to kill most ingested pathogens?
Acid and enzymes
Where does the pathogen actually get killed in the phagocyte?
Phago-lysosome
What receptors are expressed on the phagocyte cell surface?
PRRs - pattern recognition receptors
What antigens are expressed on pathogens that are recognized by phagocytes?
PAMPs - pathogen-assocaited molecular patterns
Does a phagocyte phagocytose only one pathogen at a time?
No, a phagocyte has many different PRRs and can simultaneously phagocytose many extracellular pathogens.
What are the key characteristics of PAMPs?
Only expressed by microbes
Low mutation rate/highly conserved since these are critical for pathogen survival
One PRR only binds to one PAMP (T or F)?
False. The same PRR can bind multiple PAMPs
Why is it important that a single PRR be able to bind many different PAMPs?
because there is a limited number of PRRs
What is the importance of innate immunity?
Allows efficient recognition of pathogens
Very effective at destroying the majority of pathogens, early
PRRs recognize host cells in the healthy condition (T or F).
False. PRRs ONLY recognize and bind to pathogens
What are the main phagocytes?
Neutrophils, macrophages, immature dendritic cell
Where are neutrophils located?
Circulate in the blood
Describe the characteristic of neutrophils.
Circulate in the blood
most abundant leukocyte in the blood
exit blood and rapidly enter into infected tissue
rapidly differentiate from myeloid progenitors in response to infection
short lived
What is pus primarily composed of?
dead neutrophils and cellular debris
What is neutropenia?
Low neutrophil count
People with neutropenia are at high risk for what?
Serious bacterial infections
Why are people with neutropenia not more susceptible to viral infection?
Neutrophils are only involved in destroying extracellular pathogens - viruses are obligate intracellular parasites, and thus not affected
What is important when treating neutropenia?
To respond quickly to early symptoms to prevent bacteria sepsis and septic shock
