Neurtrophils and Eosinophils Flashcards
What is the structure of the nucleus of neutrophils?
it is condensed chromatin - segmented
What are neutrophils considered in regards to a bacterial infection?
it is the first line of defense
How long do neutrophils circulate?
8-10 hours
What are neutrophils removed by?
migration into the gut or by Kuepfer cells in the liver
How long can neutrophils live in normal tissue?
1-2 days
In tissues, how do neutrophils die?
via apoptosis
Are neutrophils innate or adaptive?
innate
What is the origin of neutrophils?
bone marrow
What are the important surface receptors on a neutrophil?
Fc receptors for IgG, C3b receptors, and selectin and integrin (cell adhesion receptors)
What is margination?
in post capillary venules, neutrophils loosely bind to endothelium via selectin adhesion molecules and roll along
How does the margination pool influence neutrophil counts in blood samples?
it will be lower than the actual number due to the rolling and adhesion
What is selectin?
a light binding adhesion molecule
What is integrin?
a tight binding adhesion molecule
What is diapedisis?
the exiting of netrophils between cells
What is chemotaxis?
when neutrophils follow the chemical gradient from a lesser to a higher concentration
Define opsonize.
coating and preparing to be eaten
Define phagocytosis.
actual process of being eaten by the cell
Define phagosome.
membrane bound vesicle made after phagocytosis
Define phagolysosome.
when the phagosome fuses with the lysosomes
Why is the interaction between opsonized bacteria and neutrophils different than the interaction with bacteria that are not opsonized?
there is no receptor mediated event in non opsinized
What are the killing mechanisms of a neutrophil?
lytic enzymes and antimicrobal peptides from granules, oxidative metabolism (respiratory burst), neutrophil extracellular traps (NETs)
What are the important molecules involved in the killing mechanisms of neutrophils?
hydrolases, lysozomes, defensins, and myeloperidoxase
What is the neutrophils most potent killing mechanism?
the oxidative burst
What mechanism do neutrophils use as a last resort that lead to their death?
neutrophil extracellular traps (NETs)
What is a defensin?
Small catatonic proteins that kill bacteria by poking a hole in their membrane, especially gram positives
Where are defensins located?
in phagocytic cell granules and produced by epithelial cells\
What can decrease neutrophil function?
glucocorticoids
Why do glucocorticoids decrease neutrophil function?
Inhibit endothelial selectin/integrin expression, Inhibit neutrophil emigration into tissues = decreased chemotaxis, Decrease neutrophil killing ability, Decreased phagocytosis
What does long term decrease in neutrophil funciton lead to?
a higher susceptibility to bacterial infections
What clinical conditions can stimulate eosinophilic response?
parasitism and allergies
How is eosinophilic response enhanced?
IgE
