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MICR 2420 > The Innate Immune System > Flashcards

The Innate Immune System Flashcards

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1
Q

what is the difference between infection and disease?

A

if the number of infecting organisms is small and the immune system is effective, a person will not get sick

to cause disease, a pathogen must: breach host defenses, survive innate defense mechanisms, multiply

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2
Q

what are the physical barriers to infection?

A

skin (contains keratin)
mucous membranes (epithelial cells tightly connected, supports barrier function, selectively permeable)
lungs (mucociliatory escalator to remove small particles, microbes are trapped in nose and cilia lining upper airway)

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3
Q

what does SALT stand for?

A

Skin Associated Lymphoid Tissue

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4
Q

what does GALT stand for:

A

Gut Associated Lymphoid Tissue

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5
Q

what are primary lymphoid organs?

A

factory for lymphoid cells

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6
Q

what are secondary lymphoid organs?

A

stations for antigen encounters

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7
Q

what are complements?

A

set of proteins made by the liver
complement antibodies in the killing of bacteria

circulate in blood, enter tissue all over body
circulate as inactive forms and are proteolytically cleaved to activate

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8
Q

what are the three complement activation pathways?

A

classical
lectin
alternative

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9
Q

how do all complement pathways converge?

A

LYTIC

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10
Q

what are the components of the alternative pathway?

A

C3b - acts as an OPSONIN (proteins that coat pathogens)
C3a and C5 - anaphylotoxins, direct immune cell traffic to where it’s most needed
MEMBRANE ATTACK COMPLEX - punch holes in target cells, killing them

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11
Q

what are cytokines?

A

molecules secretes by a cell that can effect other cells
ex. interferon, which act as an alarm bell, helping other cells nearby fend off the virus

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12
Q

what molecule is found in the gut?

A

high concentration of DEFENSINS

higher concentration in close proximity to the crypts of the epithelium

secreted from crypts

keeps out even normal microbiota

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13
Q

what defence cells are found in white blood cells?

A

polymorphonuclear leukocytes
monocytes
macrophages
dendritic cells
mast cells
lymphocytes

1 litre of human blood contains 6 billion WBCs

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14
Q

what do myeloid bone marrow stem cells differentiate into?

A

PHAGOCYTES

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15
Q

why are bacterial cells hard to catch?

A

REPULSION
bacterial cells carry a negative charge, so do phagocytes

C3b binds to the surface of proteins, making it easier for phagocytes to bind

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16
Q

describe NEUTROPHILS

A

capture pathogens with NETs
sense and invader and spews a latticework of chromatin and antimicrobial compounds
prevents spread of the pathogen
allows rapid phagocytosis

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17
Q

what can interfere with NETosis?

A

a CAPSULE

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18
Q

what are monocytes?

A

differentiate into macrophages
circulate in the blood stream
attracted to by cytokines to where they are needed
differentiate while travelling through blood vessels

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19
Q

what are macrophages?

A

large structures that can ingest many microbes at once

can also be found in organs
ex. kuppfer cells in the liver, langerhans in the skin, microglia in the brain, alveolar macrophages in the lung

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20
Q

what are dendrocytes?

A

finger-like projections, give cells a bigger surface area
posess long protrusions that can squeeze through tight spaces into samples

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21
Q

what is inflammation?

A

a key part of the innate immune response

signs: heat at site, edema, redness, pain, altered function (cell is dealing with infection)

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22
Q

what is pus?

A

dead neutrophils

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23
Q

why is long term inflammation bad?

A

extremely hard to kill some microbes - have a thick cell wall and slow reproduction time

ex. mycobacterium tuberculosis, fish tank granuloma, chrones disease

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24
Q

describe phagocytes as antigen presenting cells?

A

process the antigens they ingest and display them on their surface for T-cells

link between innate and adaptive immune system

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25
what are peyer's paches?
specialist sites within the small intestine rich in "M-cells", uptake of antigens in the gut to present to macrophages help body differentiate between friend and foe
26
how do pathogens evade the immune system?
CAPSULES - slippery, stain with India Ink ex. strep. pneumoniae, neisseria meningitidis, bacillus anthracis
27
how are pathogens recognized by the immune system?
specialized set of receptors that recognize INVARIANT and ESSENTIAL microbial factors that are UNIQUE to the immune system called: PATTERN RECOGNITION RECEPTORS recognize: MICROBE ASSOCIATES MOLECULAR PATTERNS do NOT discriminate between good and bad
28
what are Toll-like receptors?
TRANSMEMBRANE receptors on some IMMUNE cells that RECOGNIZE VIRAL AND BACTERIAL PRODUCTS ligand bonding (molecule that binds to another molecule to send signals between cells): stimulate CYTOKINES to signal inflammatory response induce macrophage response
29
what are NODs and NOD-LIKE RECEPTORS?
used if pathogen is INSIDE a host cell bind to MAMPs and activate cytokine production form an INFLAMMASOME that activates apoptosis ("good" cell death)
30
what are the types of cell death?
NECROSIS: "bad" cell death, leakage of cellular components, triggers cell death APOPTOSIS: packages up nicely, phagocytosis of cells and fragments
31
how many toll-like receptors are there?
SEVEN ****MISSING 7 and 8 1,2,4,5,9 --> recognize BACTERIA 3 --> recognize viruses 6 --> recognizes mycoplasma LGDLFDU OUTSIDE CELL
32
how many NOD-like receptors are there?
FOUR 1 --> grame NEGATIVE bacteria 2-4 --> bacteria CPPF INSIDE CELL
33
what are inflammasomes?
protein complexes that allow rapid secretion of cytokines
34
what are NATURAL KILLER CELLS?
NOT PHAGOCYTIC large and granular role in innate defense ATTACK HOST CELLS THAT HAVE BECOME OVERWHELMED BY PATHOGENS
35
describe the mechanism of NKCs
ALERTED by interferons or cytokines infected host signals an ALTERED SELF response NK cell binds to infected cell, punches holes in membrane GRANZYME moves through pores, triggers APOPTOSIS
36
what is EFFEROCYTOSIS?
allows dying cell to be neatly packaged before death small enough for neutrophils to consume via EFFEROCYTOSIS neutrophils dispose of apoptotic cell bodies WITH intruder microbes inflammation kept to a minimum
37
what is the adaptive immune system
branch with MEMORY
38
what are the types of adaptive immune?
T-cells: RECOGNIZE antigens on infected cells, TARGET infections B-cells: ANTIBODIES target invaders, target infections of the body's fluids like a WEAPONS CACHE
39
describe adaptive immunity
develops 3-4 days following exposure to invading microbe recognizes small pieces of a given antigen - EPITOPES, produced by PHAGOCYTOSIS
40
what are HAPTENS?
a molecule that is too small to elicit an immune response, must be BOUND to another molecule to act as an antigen
41
what macromolecules elicits the best immune response?
IMMUNOGENICITY 1. Proteins --> greatest diversity in shape 2. Carbs 3. Nucleic acids and lipids
42
describe T-cell education
happens in the THYMUS begins shortly before birth thymus shrinks as we grow older as cells mature, they develop a T-cell RECEPTOR --> each receptor recognizes a different antigen
43
describe "thymus college"
T-cells must be able to identify MHC peptides, tested for reactivity against self-antigens understand commands, well disciplined 98% of T-cells are KILLED
44
what are the types of "effector" T-cells?
CYTOTOXIC T-cells: trained ASSASSINS, destroy cells presenting noxious antigens HELPER T-cells: memorize databanks of antigens and ALERT B-cells if a circulating antigen is detected
45
what are MEMORY t-cells?
retain antigen affinity act as effector cells during reinfection short lifecycle, replicate hazy memory over time, why we need booster shots
46
what are REGULATORY t-cells?
RESTORE HOMEOSTASIS after infection lack of these cause chronic inflammation
47
what are MHC proteins?
the proteins infected cells place on antigens to display to the immune system infected cell loads antigen to show they are infected allows T-cells to recognize self vs antigen
48
what is MHC1?
display antigens on the SURFACE of the infected cell
49
what is MHCII?
display antigens on the surface of APCs
50
what is the initiation of cell-mediated reponse?
APCs that have phagocytosed a pathogen travel to lymph nodes to display captured antigens to display captured antigens binding of antigen loaded MHCs to receptors activates T-cells, cell-mediated adaptive immune response begins cytotoxic T-cells can directly kill an infected host
51
describe t-cell deployment
travel to LYMPH NODES otherwise, t-cells and APCS will not find each other 4x10^11 t-cells in body 10 T-cells will recognize same pattern - CLONOTYPE
52
describe helper T-cells and the humoral response
some T-cells activate B-cells B-cells undergo education in bone marrow, only recognize 1 antigen epitope B cell activates when a helper T-cell presents the same antigen to a B-cell as the one on its receptor
53
what do B-cells differentiate into?
PLASMA cells live 4-5 days, but produce 2000 antibodies per second
54
what is B cell and T-cell tolerance
ANTIGEN DOSE if the antigen does is over the threshold value, B and T cells become overstimulated, do not respond realize it is not killing you
55
describe the anatomy of an antibody
forms a T shape top is antigen binding site (F(ab)) pepsin cleavage site in the middle Fc fragment at the bottom
56
what binds antibodies together?
disulfide bonds
57
how many polypeptide chains are in an antibody?
4 - 2 heavy, 2 light
58
what are constant regions?
conserved amino acid sequences 5 heavy chain types: alpha, mew, gamma, delta, epsilon (defines antibody class) 2 light chain types: Kappa, lambda
59
what is an isotype?
defines various chains belonging to a SPECIES
60
what is an allotype?
differences in the constant region shared by some, but not all, members of a species
61
what is an idiotype?
differences in hypervariable region within an individual REMEMBER: idiots are hyper
62
what is IgG?
simplest, smallest, most ABUNDANT 4 classes binds and opsonizes microbes neutralizes viruses activates classical pathway
63
what is IgA
secreted antibody my MUCOSAL surfaces found as a DIMER --> can bind 4 antigens secretory piece wrapped around both molecules during secretion found in tears, breast milk, mucose
64
IgM
can be found as MONOMERS on B-cells most commonly found as a pentamer can bind to 10 antigens FIRST antibody detected during infection
65
what is IgD?
trace amounts, in blood monomeric on surface of B-cells does not bind to complement
66
what is IgE?
trace amounts in blood more prominently of surface of mast cells and basophils cells degranulate and amplify immune response AMPLIFY body's response to invaders
67
what are allergies
IgE triggers release of chemicals such as histamines from mast cells or leukotrienes harmless antigens perceived as threats
68
what is anaphylaxis?
severe form of an allergy excess histamine triggers smooth muscle contraction in lungs, weakens junctions between cells lining blood vessels epipens: block process of degranulation. deliver spinephrine
69
describe complement as part of adaptive immunity
alternative pathway: C3b binds to bacteria --> forms MAC antibodies made activate complement through the classical pathway
70
what is the classical pathway?
C1 complex binds Fc region C1 cleaves C4 and C2 --> rejoin to make C3 convertase C3 cleaves into C3a and C3b C3B JOINS C3 CONVERTASE TO MAKE C5 CONVERTASE convertase cleaves C5 to C5a and C5b C5b forms MAC
71
how is the lectin path similar?
lectins produced in liver, bind to sugars on bacterial cells trigger formation of C3 convertase same as classical pathway
72
why do we need 3 pathways?
people missing pathways susceptible to blood-borne illnesses --> shape shifting pathogens change antigens regularly to elude immune system ex. Neisseria meningitidis, neisseria gonorrhoeae, salmonella typhi
73
what are the components of the gut microbiome?
1. epithelial barrier: studded with T-cells 2. Dendritic cells: between epithelial cells to sample antigens 3. M cells also sample antigens sIgA --> coats microbita components considers a threat
74
where are there the most TLRs?
on the lumen facing side of epithelial cells (see more antigens) less on basal side

MICR 2420 (9 decks)

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