Innate Immune System Flashcards
what cells are sentinel cells
macrophage
dendritic cells
what cells have phagocytic functions
macrophages
neutrophils
what cells are antigen presenting cells
macrophages
dendritic cells
what are the ways a cell can create signals intercellularly
- cell surface receptors
- small soluble molecules
when are cell surface receptors expressed
mostly when induced
what can a cell surface receptor be used for
- binding signaling molecules from other cells
- bind microbes and host cells
what are types of intercellular signaling used in the innate immune system
- cell surface receptors
- small soluble molecules
what is the fate of the signals secreted from the cell
bind on receptors of other cells
how do cells bind to each other
using complementary receptors
True or False:
Cells integrate/regulate intercellular signals in a regulated manner
true
what are the functions of the signals sent to other cells
- divide/stop dividing
- die
- express receptors
- secrete more signals
what is released in the event the cells of the immune system are activated
cytokines
what are cytokines
small, soluble protein molecules
what are the main cytokines
- interleukines
- lymphokines
- chemokines
- interferons
besides communication with other cells and impact on cellular behavior, what are cytokines’ function
growth
differentiation
secretion
where can cytokines be present
local or systemic
what is needed for a cell to be able to respond to a cytokine
receptors
True or False:
One type of cytokine can be made by several different cells
true
how is the function of a cytokine determined
per situation
what is the MAIN result of the activation of cytokines
initiates inflammation
what cytokine acts as growth and differentiation factors for cells of the immune system
interleukins
which cytokine is secreted by lymphocytes
lymphokines
which cytokine has pro-inflammatory and chemotactic properties
chemokines
what cytokine can interfere with viral replication
interferons
which cytokine kills tumor cells and also can regulate inflammation
tumor necrosis factor
what are the primary activators of the innate immune system
sentinel cells
what is the job of sentinel cells
recognize invader or tissue damage
which sentinel cell is responsible for identifying, capturing, and killing microbes
macrophage
True or False:
Macrophages are not APCs
False
Macrophages are APCs because of their presence of cell surface receptors
what cell is the primary antigen-presenting cell
dendritic cell
how do macrophages and dendritic interact with the acquired immune system
through antigen presentation
where can you find sentinel cells
highest concentration at infection site
what do sentinel cells and all phagocytic cells express on their surface
Pathogen Recognition Receptors (PRRs)
what do PRRs recognize
Pathogen-Associated Molecular Patterns
(PAMPs)
what are PAMPs
conserved molecular patterns on microbial surfaces
what is the purpose of the Pathogen Recognition Receptors?
They are used to recognize molecular patterns on the surface of microbes
why is inflammation the main result of the release of cytokines by sentinel cells
- increased vascular permeability
-increased blood flow - attraction of neutrophils to the site
what is the major mechanism of the innate immune response to a microbe
inflammation
what are the signs of inflammation
- redness
- swelling
- heat
- pain
- loss of function
what phagocytic cell is found in the blood
monocytes
what phagocytic cells is found in tissues
macrophages
what are the polymorphonuclear cells
-neutrophils
-eosinophils
-basophils
what activates phagocytic cells
dead and dying cells
how are tissue macrophages named
based on location
what is the impact steroids have on macrophages
down-regulated
how would steroid use impact the immune system
decreases the ability of macrophages to kill pathogens
with what clinical sign should be hesitant/ cautious to use steroids with
inflammation
why should we be careful using steroids with cases of inflammation
inflammation could be caused by infection and steroids would decrease macrophage abilities
what is the major phagocyte to respond to infection
neutrophils
where can you find neutrophils?
-high numbers in circulation (blood)
-bone marrow
what do we count in a CBC
amount of neutrophils in the circulating pool
what is the presence of above normal concentration in the circulating pool
Neutrophilia
what are the two places in circulation the neutrophils can be found?
- circulation pool
- marginating pool
where is the marginating pool of neutrophils found
adhering to endothelium
in what species can there be 3x more the amount of neutrophils in the MP than CP
cats
what can stress in cats cause to be shown on a CBC
neutrophilia
what is the importance of bone marrow when it comes to neutrophils
- proliferation pool
- maturation pool
- storage pool
what leads to the death of neutrophils
phagocytosis
what is attracted to dying neutrophils
macrophages
which neutrophils do no undergo proliferation
circulating & mature
when do neutrophils become active
immediately after release from bone marrow
True or False:
Neutrophils are used for long-term killing
FALSE
incapable of sustained killing
what receptors are present in neutrophils
- surface receptors for complement proteins
- receptors for Fc part of antibody
do macrophages or neutrophils have a greater speed of response for phagocytosis
neutrophils
which phagocytic cell is involved in tissue repair and APCs
macrophage
what is the 1/2 life of blood monocytes
1 day
what is the life span of tissue macrophages
several months or years
which phagocytic cell has greater antimicrobial abilities
macrophages
what are the main defense factors of phagocytes
-enzymes
-defensins
-interferons
-complement proteins
what is used by phagocytes to cause oxidative damage to membranes
enzymes
what is a defensin
anti-bacterial peptide
what can be produced by phagocytic cells to interfere with viral replication
interferons
what is produced by macrophages and hepatocytes
complement proteins
what coats microbes and enhances phagocytosis
opsonins
what is the function of the receptors on the phagocytic cells
recognize molecules on pathogens
what is a cell surface molecule that promotes adherence of a cell to various things
integrens
True or False:
phagocytic cells have receptors for complement proteins
true
what is the purpose of a complement protein
coat microbes for ID
what are complement proteins similar to (slightly mimic)
opsonins
what is the purpose of having receptors for complement proteins and Fc part of the antibody receptors
cells can now see and bind to the microbe because of the coating
how are phagocytic cells able to coat microbes in order to reveal them
complement proteins
what is the name of the mechanism used by phagocytes to facilitate adherence to microbes through complement proteins
opsonization
what are the 4 steps to phagocytosis
- Chemotaxis
- Adherence
- Ingestion
- Destruction
what is directed migration according to the chemical gradient
chemotaxis
what happens after a phagocyte arrives to the site of inflammation
adherence to epithelium via integrins
in a clinical case of pyoderma, what diagnostic test would be used to confirm the case
impression smear of skin
in what clinical case would you see an impression smear of skin filled with many phagocytes
pyoderma
after the phagocytes arrive at the site of infection, what cells come in to kill the organism in the innate immune system
neutrophils
what do phagocytic cells use to recognize microbes
adherence
what is used to promote adherence in macrophages and neutrophils
- receptors of Fc part of Ab
- Opsonins
-receptor for complement protein - PRR
True or False:
all macrophages and neutrophils cant express identical receptors
FALSE
they can express identical receptors for recognizing microbes (PRRs)
what are often molecules essential for the survival of the microbe
Pathogen-Associated Membrane Patterns
PAMPs
what is unique about PAMPs that makes them the ideal protection for survival
do not mutate or change expression
what is the most important group of PRRs
Toll-like receptors (TLRs)
where are Toll-like Receptors present
-cell surface
-intracellular
what is the purpose of cell surface TLRs
recognize extracellular invaders
What is the purpose of intracellular TLRs
detect intracellular viruses
True or False:
A TLR is a PRR
true
what do TLRs interact with
PAMPs
what is the result of a TLR signal to the host cell
- killing of microbe
- production of cytokine resulting in inflammation
what are two destruction mechanisms used in the innate immune system by phagocytic cells
oxygen-depending & oxygen-independent killing
which phagocytic destruction mechanism is essential to survive
oxygen-depending killing
which destruction mechanism can we expect to take place in a low pH environment
oxygen-independent
in what cell type can Mycobacterium bovis and Rhodococcus equi survive
macrophages
True or False:
some pathogens can become resistant to lysosomal contents or inhibit phagolysosomal fusion
true
what clinical cases can be seen to inhibit phagolysosomal fusion
- Mycobacterium bovis
- Rhodococcous equi
- Brucella abortus
- Listeria monocytogenes
- Salmonella typhimurium
what cell will not only kill the microbe but also the host cell
natural killer cells
True or False:
NK cells and CTLs have the same recognition mechanism for host cells
False
CTLs need antigen to be presented
True or False:
NK cells kill microbes directly as well as infected host cells
FALSE
NK cells are only responsible for killing the infected host cell
what makes NK cells dangerous if left unregulated
they do not need an antigen present for activation. They will kill any host cell they deem infected
what can NK cells express to antibodies
FcR
how can an NK cell identify an infected host cell
a host cell will have antibody attached to the surface and the FcR on the NK cells will attach to it
how can NK cells recognize antibodies made for foreign material
B-lymphocytes make the antibodies for the NK cell to recognize
what is Antibody-dependent cell-mediated cytotoxicity (ADCC)
Interaction between FcR and antibody on the cell triggering the NK cell to release cytolytic granules
what is the purpose of cytolytic granules
initiates apoptosis of the host cell
how would ADCC be useful in drug development
antibody specific for tumor antigens can lead NK cells to kill the tumor cell faster and more effectively
what mechanisms do NK cells use to target cells
- ADCC
- Receptors for complement proteins
- lack of MHC-1 expression
how are NK cells effected by the presence of MCH-1 molecules
inhibited by the host cell
what does MHC-1 molecules signal for
normalcy / healthy cells
True or False
All normal, nucleated cell can express MHC-1
true
what occurs is the host cell does not express any MHC-1 molecules
the NK cell will try to kill it because “it is not normal”
what are NK cells regulated by
cytokines
