Module 2 Flashcards
(158 cards)
1
Q
is the innate specific or not
A
not
1
Q
what is the innate immunity
A
first line of defense against foreign invaders
- early phases of an immune response
2
Q
innate immunity: immune barriers
A
made of physical, soluble, and cellular barriers that are scattered throughout the body
3
Q
innate immunity: inflammation
A
responds immediately to an invading pathogen
- is a breach of the physical barrier by a pathogen is called inflammatory response
4
Q
innate immunity: pattern-recognition
A
- recognizes general patterns not specific for any one antigen
5
Q
how does pattern recognition work
A
by pattern-recognition receptors (PRR) expressed on innate immune cells
6
Q
innate immunity: phagocytosis
A
phagocytic properties (engulfing) are called phagocytes
7
Q
what are the immune barriers of the innate immune system
A
physical barrier
cellular barrier
soluble barrier
8
Q
physical barrier
A
made of every structure located at the interface between the inside and the outside of the body
- physical and chemical components
9
Q
examples of physical barrier
A
skin, cilia, bodily secretions
10
Q
cellular barrier
A
made of various cells which play a role in the innate immune response
11
Q
examples of cellular barriers
A
- neutrophils
- macrophages
- dendritic cells
- natural killer cells
12
Q
soluble barrier
A
made of macromolecules which contribute to the mediation of an innate immune response
13
Q
examples of soluble barrier
A
complement and cytokines
14
Q
physical components (physical barrier)
A
skin
- barrier that pathogens cannot cross unless it is breached
mucous membrane
- cover body cavities
- contain cilia and produce mucous
15
Q
chemical component (physical barrier)
A
tears and saliva
- contain active antimircobial substance such as lysozyme, gastric acid
16
Q
lysozyme
A
catalyzes the destruction of the cell walls of certain bacteria
17
Q
cellular barrier: neutrophils
A
- most common leukocyte in blood
- phagocytes (engulf and destroy)
- in blood for 12h before entering tissue by diapedesis
- recruited to site of infection by macrophages
- 1-3 days of life in tissue
18
Q
cellular barrier: macrophages
A
- phagocyte that patrols the body to engulf pathogens
- be in specific tissue or move freely/patrol large areas tissues
- contributes to tissue repair and present antigens to other immune cells like T-Cell
19
Q
when does macrophages become activated
A
after phagocytosing pathogens or in response to cytokine signalling
19
Q
diapedesis
A
process by which blood cells such as neutrophils move from blood to tissues by passing through intact vessel walls
20
Q
cellular barrier: dendritic cells
A
- phagocyte often in contact with the external environment
- present antigens on their cell surface through peptide: MHC complexes, which can be rexognized by helper T-cells
21
Q
what is a big function of dendritic cells
A
major link between the innate and adaptive immune system
22
Q
cellular barrier: natural killer cells
A
- recognize abnormal cells lacking antigen-specific receptors
- destroy abnormal cells
(tumors, virus) - bind to cell surface of target cells and release chemicals causing them to die
23
soluble barrier: complement system
what is it?
- made up of over 30 soluble proteins
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soluble barrier: complement system
where is it?
circulate in the blood, normally in an inactive form
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soluble barrier: complement system
when is it activated
directly activated in the presence of extracellular pathogens or indirectly by pathogen-bound antibody
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soluble barrier: complement system
how is it activated
cascade of reaction between various complement proteins, leading to formation of a membrane attach complex (MAC) and in parallel, enhances or complements the efficiency of other immune function, such as inflammation and phagocytosis
27
soluble barrier: complement system functions/what are the three activating pathways
classical, alternative, and lectin pathways
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soluble barrier: complement system functions
inflammation, phagocytosis, membrane attack complex
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soluble barrier: complement system-inflammation
includes the attraction of various immune cells to the site of infection through the release of chemotactic molecules, such as histamine and cytokines
- activated complement proteins bind to complement receptors on immune cells, such as mast cells and basophils, and release of these substances which enhance the inflammatory response
30
chemotactic molecules
including the movement of cells toward the site where the substance are originally released
- histamine
- cytokines
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soluble barrier: complement system- phagocytosis
activated complement proteins, predominately C3b, opsonize pathogens thereby targeting them for destruction by phagocytes
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opsonize
making a foreign particle more susceptible to phagocytosis by binding to the antigen and marking for ingestion
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soluble barrier: complement system- membrane attack complex
destroy extracellular foreign invaders through the formation of membrane attack complexes
- creates holes in the pathogen which leads to its lysis and death
34
what would be the result of a complement deficiency?
there would be reduced lysis of microbes and less inflammation.
- resulting in reduced bacterial clearance and therefore longer periods of infection
35
soluble barrier: cytokines
- small proteins secreted by various immune cells in response to a number of different stimuli.
- chemical mediators that play a key role in cell-to-cell communication
36
what do cytokines have a strong affinity for
specific type of cytokine receptor
- they are expressed on the cell surface of various immune cells depending on their needs/functions
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what is the function of cytokine signaling?
is to regulate immune process, such as immune responses, inflammation and hematopoiesis
38
soluble barrier: autocrine Vs endocrine
autocrine- the sending and receiving cell is the same
paracrine- the sending and receiving cells are near to each other
endocrine- the sending and receiving are distant from each other
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what do majority of cytokine do
act locally, having autocrine or paracrine effects
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soluble barrier: specificity and affinity
cytokines bind to specific receptors on the membrane of their target cells
- cytokines and their receptors exhibit very high affinity for one another
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soluble barrier: alter gene expression
- cytokine binding to its receptor initiates a series of reactions that ultimately alter gene expression, which may affect cell growth and maturation, and have roles in the hosts response to infection and disease
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soluble barrier: pro-inflammatory cytokines
- made by most immune cells
- when secreted will induce an inflammatory response within the body
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soluble barrier: anti-inflammatory
- made by several immune cells and work to limit the inflammatory response within the body
- do so by inhibiting pro-inflammatory cytokine production and activating immune cells that promote healing
44
what happens if there is a shift in the balance towards one side or the other of anti- and pro inflammatory cytokines
if pro are not properly controlled, they lead to complications such as tissue damage due to an excessive inflammatory
- if anti are not controlled, a lack of an immune response to a pathogen may occur which can result in spreading of the pathogen
45
what happens when a pathogen evades the physical barriers of the innate immune system
the surrounding cells work to induce an inflammatory response
46
where does inflammation occur
as a localized tissue response to injury or invasion and has both local and systemic effects within the body
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how can inflammation be characterized?
redness
heat
pain
swelling
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what happens during inflammation? steps;
- alteration of blood flow to the injured area
- influx of phagocytic and other immune cells
- removal of foreign antigens
- healing of damaged tissue
loss of function
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what is the main purpose of inflammation?
the bodies attempt at self-protection by removing harmful stimuli, including damaged cells, irritants or pathogens
- localize and eliminate the invading pathogen, in an effort to stop it from spreading and to remove damaged tissue
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major events of inflammation: 1.
Breach
- pathogen needs to find a breach in skin to enter body
- a cut and pathogen can enter
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major events of inflammation: 2.
vasodilation
- increase in diameter of blood vessels and permeabilization of the capillaries near the affected area
- changes are induced by vasoactive and chemotactic factors secreted by damaged tissues and activated immune cells, like macrophages and mast cells
52
major events of inflammation: 3.
permeabilization
- vasodilation results in the increase in capillary permeability facilitating the entrance of fluids in tissues
- with vasoconstriction from carry blood area from cut allow accumulation of excess fluid at the site of infection called exudate
53
exudate fluid
Exudate fluid contains proteins that help with inflammation. **These include:**
Pro-inflammatory cytokines (like chemokines) and complement proteins.
These proteins attract immune cells to the infection site to help fight pathogens.
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the swelling characteristic of inflammation is a consequence of accumulation of fluids at the infection site is called what??
edema
55
major events of inflammation: 4.
extravasation
- the chemotactic factors released by cell during the vasodilatation and permeabilization steps induce the recruitment of more immune cells to the site of infection
- when neutrophils that are circulating in the blood arrive to an infection site, they adhere to the endothelial cell walls via process called margination and migrate between the capillary-endothelial cells into the infected tissue by extravasation or diapedesis
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what are the first type of cells to arrive by chemotaxis
neutrophils
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major events of inflammation: 5.
phagocytosis:
- at infection site, neutrophils, phagocytes, macrophages, dendritic cells engulf the pathogens
- is one of the major processes used by innate cells to destroy extracellular pathogen
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why is heat and swelling beneficial during an inflammatory response
heat increases the metabolic rates of cells allowing them to repair themselves faster
- swelling leaks proteins which help clot blood and form scabs, and recruits local phagocytes and lymphocytes to help destroy pathogens and clean up dead cells
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how is the innate immune system able to recognize structure as being self or non self
pattern recognition receptors (PRRs)
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patter recognition receptor
capable of recognizing repeated molecular patterns of pathogens
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example of patter recognition
Toll-like receptors (TLRs)
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where do PRRs come from
has to be able distinguish self from non self
- that is unique to the microorganisms and necessary for their survival
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are PRRs in innate and adaptive immune cells
they are in both however, they are an integral signaling component of the innate immune system
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molecular pattern
- recognized by PRRs are conserved motifs and certain subsets can be found in various groups of pathogens
called pathogen-associated molecular patterns (PAMPs)
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PAMPs
are molecular structure either expressed on the surface of or found inside pathogens
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examples of PAMPs
lipopolysaccharides (LPS) found on the cell surface of gram-negative bacteria
- double stranded RNA found inside dsRNA
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are the molecular patterns found in host cells?
not found in host cells, which gives the ability to innate cells to distinguish non-self from self
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what are two major categories of molecular patterns that can be recognize by PRRs
- pathogen-associated molecular patterns (PAMPs)
- danger-associated molecular patterns (DAMPs)
- play a key role in the ability of innate immune cells to recognize invaders
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pathogen-associated molecular pattern (PAMP)
- molecules associated with groups of pathogen that are recognized by immune cells:
- functional structures of a pathogen
- repeated sequences of protein, glycoprotein, lipoprotein, amino acids
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examples of PAMP
- lipopolysaccharide
- peptidoglycan
- flagellin
- viral nucleic acids
71
damage-associated molecular pattern (DAMP)
- molecules released by stressed cell undergoing necrosis
- are host biomolecules
- indicate damage to the body
- initiate an inflammatory response
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examples of DAMP
- abnormal location of a cell structures
eg. DNA found outside of mitochondria or the nucleus
- cell-stress indicator molecule
eg. heat-shock proteins
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toll-like receptors (TLRs)
- are a class of PRRs whose signalling play an essential role in the innate immune response
74
where are TLRs expressed?
on the plasma membrane or endosomal/lysosmal membranes of mammalian cells depends on the type of PAMP or DAMP it recognizes
75
before activation what to toll-like receptors initiate the transcription of gene encoding for;
- inflammatory cytokines
- chemokines
- costimulatory molecules
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what are the two major roles or toll-like receptor
- recognize PAMPs and/or DAMPS
- induce expression of signaling to activate T-cell
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TLR signaling process 1.
sense the presence of an infection through recognition of PAMPs and/or DAMPs
- the bacterium will be engulfed through phagocytosis by the phagocytic cell, (ex. dendritic cell)
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TLR signaling process 2.
after engulfing the bacterium, the immune cell, (antigen presenting cell) will present pieces of the pathogen on its cell surface through peptide :MHC complex
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TLR signaling process 3.
the antigen presenting cell will also increase its production of costimulatory molecules, which are involved in the strength and the stability of the antigen presenting process
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TLR signaling process 4.
an immunocompetent naive T cell specific for the antigen presented by the dendritic cell will bind to the peptide: MHC complex through its TCR
- activating the T-cell and make adaptive immune happen
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phagocytosis
is an example of the next line of defense against the invading pathogen within innate immunity
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what is phagocytosis
- type of endocytosis
- cell takes up particulate material from its environment by invaginating's its membrane to form a vacuoles
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how can phagocytosis be induced
the recognition of a PAMP by phagocyte through its PRR is one way
- pathogen opsonization
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neutrophil
- first cell to arrive from blood to the site of infection
- early phagocytosis, quickly
- initiate an inflammatory response
86
macrophages
- monocytes migrate from blood to tissue to become macrophages
- most efficient at phagocytosis
- release cytokines that stimulate inflammation and recut other immune cells
87
dendritic cells
- recognize microbes and initiate phagocytosis
- most efficient antigen presenting cells
- play a major role in initiations of adaptive immune response
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steps of phagocytosis 1.
attachment
- the pathogen becomes attached to the membrane evaginations called pseudopodia
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evaginations
a protruding structure produced by turning a membrane outward
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steps of phagocytosis 2.
ingestion
- the pathogen gets ingested
- forms a vacuole (phagosome) within the cell
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phagosome
a vesicle composed of cell membrane of a phagocyte, containing the phagocytosed material
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steps of phagocytosis 3.
fusion
- phagosome fuses with a lysosome, releasing lysosomal enzymes that degrade macromolecules and other materials such as bacteria
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steps of phagocytosis 4.
digestion
- the pathogen is destroyed and digested by the lysosomal enzymes
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steps of phagocytosis 5.
release
- digestion products are released from the cell via exocytosis
- the vacuole membrane fuses with the cell membrane
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what are the 4 major components of the cellular barrier
- neutrophils
- macrophages
- dendritic cells
- natural killer cells
96
true or false
toll-like receptor family contains membrane-bound receptors which contribute to the activation of innate immune cells by recognizing pathogen-associated molecular patterns of invaders
True
97
what is the main functions of the complement system made of?
- opsonization (phagocytosis)
- chemotaxis (inflammation and lysis through membrane attack complexes)
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what are the major steps of inflammation
vasodilatation
permeabilization
extravasation
phagocytosis
99
characteristics applicable to cytokines
- chemical mediator
- specificity
- alter gene expression
- pro-inflammatory
- anti-inflammatory
100
major steps of phagocytosis
- attachment
- ingestion
- fusion
- digestion
- release
101
about adaptive immune
is the second line of defense
- longer time to initiate
creates specific response
- memory cells to respond faster and stronger
102
adaptive immune system: specificity
each cell of the adaptive immune system recognizes one specific epitope of pathogen
103
what happen each time the adaptive immune system encounters a pathogen
it creates a unique immune reaction to eliminate the infectious agent
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epitope
also called antigenic determinant, it is a part of an antigen recognized by adaptive immunity components
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what are the major characteristic's of adaptive immunity
specificity and diversity
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adaptive immunity: diversity
because it is specific it is composed of countless numbers of cells to be able to fight any pathogen encountered
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what can adaptive be further divided into
humoral immunity
cell-mediated immunity
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cells of the humoral immunity
- B-cells
- antibodies
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cell-mediated immunity
T-cells
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what is humoral immunity characterized by
b-cells which differentiate into specialized subsets following their activation
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B-cell characteristics
- key component of humoral response
- mature in the bone marrow
- surface receptor B-cell receptor (BCR)]
- antibody factory
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B-cell subsets
plasmocyte
memory b-cell
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plasmocyte
- effector cell
- produce large quantities of antibodies
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memory b-cell
memory cell
- express BCR on their cell surface
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what is cell-mediated immunity characterized by
t-cell
116
t-cell specificity
key component of the cell-mediated response
- mature in the thymus
- surface receptor: T-cell receptor (TCR)
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function of t-cell
cytotoxic activity or help the activation of immune response
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t-cell diversity
CD4 helper t-cell
CD8 cytotoxic t-cell
memory t-cell
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CD4 helper t-cell
effector cell
- help the activation of the adaptive immune response
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CD8 cytotoxic t-cell
- effector cell
- kill infected cell
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memory t-cell
memory cells
- express TCR and CD4 or CD8 on their cell surface
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activation of adaptive immunity
- antigen presenting cells (APCs), like dendritic cells, that have engulfed pathogens by phagocytosis can present the antigens to naive CD4 helper t-cells
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differentiation of adaptive immune system
depending on type of antigen it encounters, t-helper cells differentiate into 2 subsets
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what are the 2 subsets during differentiation of adaptive immunity
1. induce cell-mediated immunity, activated by t-helper with differentiate into t-helper 1
2. induce humoral immunity, activated by t-helper cells with differentiate into t-helper 2
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activation steps of humoral immune response
1. activated and differentiated t-helper 2 cells activate B-cells and induce their differentiation into plasmacytes
2. plasmacytes produce antibodies specific for the invading antigen
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steps to activate a cell-mediated immune response
1. activated and differentiated t-helper 1 cells activate CD8 cytotoxic t-cells and induce their differentiation into CTL
2. CTL recognize and eliminate cells displaying specific antigen presented at their cell surface by M
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what are antibodies?
immunoglobulin or AB
- large y shaped protein
- each antibody is highly specific and recognizes one epitope
128
where do antibodies come from?
are produced by b-cells and exists in 2 forms
- one b-cell will produce one specific antibody for one specific epitope
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what are the 2 forms antibodies exist in
surface antibodies
soluble antibodies
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surface antibodies
membrane bound on B-cells, forming part of the b-cell receptor (BCR)
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soluble antibodies
secreted by B-cells (plasmocyte) and circulate freely in the blood
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b-cell receptor (BCR)
is made of a membrane-bound antibody and signal transduction molecules
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what are the antibodies functions
humoral immunity
- eliminate a pathogen
134
how does an antibody eliminate a pathogen
- neutralization
- opsonization
- complement activation
- effector cell activation
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neutralization
neutralize the biological effect of a pathogen or a toxin
136
opsonization
mark foreign invaders for phagocytosis
137
complement activation
induce the formation of membrane attack complexes and opsonization
138
effector cell activation
recognized by immune cells when bound to antigen and activate the cells effector functions
139
what is the basic structure of an antibody
are 2 heterodimeric proteins that are held together by disulfide bonds (s-s)
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antibody structure: left chains
2 of them
- is a protein subunit that forms part of the main antigen-binding region of an antibody
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antibody structure: heavy chains
2 of them
- majority of the structure of the antibody
- forms part of the antigen-binding region and forms the Fc region
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antibody structure: antigen binding regions
2 of them
- is variable and changes from one antibody to another, but remain the same on one antibody
- these regions are responsible for the diversity and the specificity of antibodies
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antibody structure: Fc region (fragment crystallizable)
- 1 of them
-constant for every antibody of the same class
- it is the part that interacts with immune cell surface receptors, called Fc receptors
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what are the 5 classes of immunoglobulins (antibodies)
1. IgG have y-heavy chains
2. IgM have u-heavy chains
3. IgA have a-heavy chains
4. IgE have e-heavy chains
5. IgD have s-heavy chains
145
what differentitates between classes of antibodies
the unique heavy chain is what makes us able to distinguish between classes
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what does the variation in heavy chain allows
- each antibody class to function in a different type of immune response
- specific amino acid sequences that confer these functional differences are located mainly within the Fc domain
147
serum
when blood is put into a centrifuge, the blood plasma or serum us the liquid that has been separated from blood cells in whole blood
147
where are the 5 classes of antibodies found
in serum
148
IgM
- forms a pentamer from IgM monomers when secreted by B-cells
148
what is the first antibody to be produces in immune response
IgM
149
what activates the complement
IgM antibody
- which then amplifies the inflammatory and adaptive response
150
IgG
- monomer when secreted by b-cells
- coats pathogens to promote phagocytosis and immune cell recruitment
- only class that can cross the placental barrier
151
placental barrier
the semipermeable layer of tissue in the placenta that serves as a selective membrane to substance passing from maternal to fetal blood
152
IgA
- forms a dimer from IgA monomers when secreted by B-cells
- first line of defense and predominant antibody class located in the body's mucosal membranes
153
IgE
monomer when secreted by B-cells
- produced in excess during allergic reactions
- role in immunity against certain parasites (helminths)
154
IgD
- monomer when secreted by B-cells
- found in large quantity on the surfaces of mature B-cells
- function or importance is unclear (maybe role during b-cell development)
