3: Components of Innate Immunity Flashcards
PMNs
polymorphonuclear cells (neutrophils and eosinophils)
What is the most numerous cells of innate immunity?
neutrophils
What is the lifespan of neutrophils?
2 days
How do neutrophils kill bacteria?
- phagocytosis
- release of pre-formed enzymes and peptides from cytoplasmic granules
- generating an oxidative burst to produce toxic oxygen byproducts
T/F: Neutrophils present antigen to T cells
F
Band neutrophil
an immature neutrophil
Heterophils
neutrophils produced by avian species and some reptiles
What cells regulate homeostatic processes and wound healing?
macrophages
Where do macrophages primarily reside?
in tissues, making them the 1st cells to do phagocytosis
What is the lifespan of macrophages?
months
Fc
fragment of crystalization; a receptor for antibody
T/F: Macrophages have Fc and complement receptors
T
T/F: Macrophages present antigens to T cells
T
T/F: Macrophages secrete cytokines
T
What are macrophages in blood known as?
monocytes
T/F: Macrophages typically recirculate back to blood from tissues
F
What are macrophages in the lungs known as?
alveolar macrophages
What are macrophages in the liver known as?
Kupffer cells
What are macrophages in the brain known as?
microglial cells
What are macrophages in the kidney known as?
mesangial cells
What are macrophages in the skin known as?
Langerhan’s cells (may also be classified as dendritic cells)
Dendritic cells are found in ___ numbers in tissues
low
Where do dendritic cells migrate to following pathogen uptake?
lymph nodes
What tissues are dendritic cells most commonly found in?
skin epithelia, intestinal, respiratory, and reproductive mucosae
APC
antigen-presenting cell
What is the most important APC?
dendritic cells
What do dendritic cells interact with to drive activation?
naive T cells
What cells provide a link between innate and adaptive immunity?
dendritic cells
Complement receptors
system of proteins that tags a foreign object
What are the 3 major phagocytes?
neutrophils, macrophages, and dendritic cells
ROP
reactive oxygen products, are a byproduct of phagocytosis
What does the phagosome fuse with to make toxic molecules?
lysosome
In what species do macrophages make very little ROPs?
avian
Where are ROPs generated?
phagolysosome
What enzyme leads ROP production?
NADPH oxidase
What is NADPH oxidase activity triggered by?
decreased pH of the phagosome
Eosinophils are present in ____ numbers
low
Where do eosinophils migrate to to complete maturation?
spleen
What cells have Fc receptors on surface for IgE?
eosinophils
What cells have bi-lobed nuclei?
eosinophils
What is the lifespan of eosinophils?
12 days
What is the lifespan of mast cells?
weeks
Where do mast cells reside?
near blood vessels in tissues
T/F: Mast cells have Fc receptors for IgE
T
What do cytoplasmic granules in mast cells contain?
histamine and serotonin
Which 2 cells perform antigen presentation?
macrophages and dendritic cells
Basophils
similar to eosinophils
Eosinophils main function
killing of antibody-coated parasites
Natural killer cells main function
kill tumor and virally-infected cells
T/F: NK cells contain an Fc receptor
T
IFN-gamma and TNF-alpha
cytokines in NK cells that drive inflammation
ADCC
antibody-dependent cell-mediated cytotoxicity
When does ADCC occur?
antibodies are bound to a target cells via specific antigen determinants expressed by the target cell; once bound, the Fc portion can be recognized by the NK cell and destroyed
Gamma/delta T cells main function
direct activity against microbial invaders
T/F: Gamme/delta T cells are part of adaptive immunity
F
Where are gamma/delta T cells found?
on mucosal and body surfaces (especially ruminants)
What are the 2 main antimicrobial peptides?
defensins and cathelicidins
Defensins
disrupt the structure and organization of microbial membranes due to electrochemical attraction
What cells express denfensins?
Paneth cells, leukocytes, and phagocytes
What cells express defensins in the male reproductive tract?
epithelial cells
Cathelicidins
small cationic peptides that are toxic to bacteria, fungi, and some viruses
What cells are cathelicidins found in?
epithelial cells, myeloid cells, and keratinocytes
What vitamin deficiency is linked to bacterial infections?
D, due to a decline in cathelicidin and defensin gene expression
What is an altered defensin gene expression associated with?
skin disease
Lysozyme
small enzyme that attacks the cell walls of bacteria
How do lysozymes destroy bacteria cell walls?
break carbohydrate chains, causing them to burst under pressure
Where are lysozymes expressed?
most mucosal membranes and within endosomes of phagocytes
Lactoferrin
a highly folded protein that binds to iron with high affinity
Where is lactoferrin found?
milk and other mucosal secretions and in neutrophil granules
What microbial molecule is very important in neonatal immunity in the gut?
lactoferrin