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2A CLINICAL SCIENCES > Immunology > Flashcards

Immunology Flashcards

1
Q

Innate immunity

A

-front-line of defence against any pathogen that attempts to attack the body
-non-specific, standardised, rapid
-no immunological memory
-does not depend on lymphocytes
-present from birth
-primitive (spread across species)

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2
Q

Adaptive immunity

A

-specific immune response which creates immunological memory and thus leads to an enhanced response to future encounters with the same pathogen
-mircrobes evade innate immunity, intracellular viruses & bacteria able to hide from innate immunity, need memory to specific antigen
-specificity, immunological memory, self/non-self recognition
-response and memory specific to antigen - quicker secondary response
-requires lymphocytes

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3
Q

Haematopoietic pluripotent stem cell

A

-haemocytoblast
-stem cell that every blood cell in the body originates from

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4
Q

Mononuclear leukocytes

A

Leukocytes with one nucleus

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5
Q

Polymorphonuclear leukocytes

A

Leukocytes with more than one nucleus

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6
Q

Examples of mononuclear leukocytes

A

Monocytes (kidney-shaped nuclei)
T cells
B cells
(lymphocytes)

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7
Q

Examples of polymorphonuclear leukocytes

A

Neutrophils
Eosinophils
Basophils

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8
Q

Neutrophils

A

-phagocytosis (innate immunity)
-2 main intracellular granules - primary lysosomes, secondary granules
-primary lysosomes - can kill microbes by secreting toxic substances

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9
Q

Monocytes

A

-phagocytosis (innate immunity)
-Ag presentation (adaptive immunity)
-differentiate into macrophages in tissues
-primary role is to remove foreign microbes or dead self matter

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10
Q

Macrophages

A

-phagocytosis (innate immunity)
-Ag presentation (adaptive immunity)
-reside in tissues
-primary role is to remove foreign (microbes) and self (dead/tumour cells)
-present Ag to T-cells

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11
Q

What is the lifespan of macrophages?

A

Months/years

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12
Q

Macrophages in the liver

A

Kupffer cells

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13
Q

Macrophages in the brain

A

Microglia

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14
Q

Eosinophil

A

-mainly associated with parisitic infections & allergic reactions
-activates neutrophils, induces histamine release from mast cells & promotes brocnhospasm

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15
Q

What stains eosinophil granules?

A

Acidic dyes (eosin)

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16
Q

Lifespan of macrophages

A

Months/years

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17
Q

Lifespan of eosinophils

A

8-12 days

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18
Q

Basophils

A

-mainly involved in immunity to parasitic infections & allergic reactions
-similar to mast cells
-binding of IgE to receptor causes de-granulation releasing histamine -> allergic reactions

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19
Q

What stains basophil granules?

A

Basic dyes

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20
Q

Lifespan of basophils

A

2 days

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21
Q

Mast cells

A

-precursor in blood
-mast cells only in tissues
-similar to basophils
-binding of IgE to receptor causes de-granulation releasing histamine -> allergic reactions

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22
Q

T lymphocytes

A

-major role in adaptive immunity
-recognise peptide Ag displayed on APCs
-T cells recognise 1 antigen -> T cell binds to antigen -> clonal selection to produce effector & memory T cells (effector T cells activate other immune cells, eg. macrophages)
-T cells do not bind to free antigens - the antigen must be associated with the MHC - MHC presents antigens to T cells
-T cells produce cytokines

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23
Q

Lifespan of T cells

A

Hours-years

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24
Q

Where do T cells originate?

A

Stem cells in bone marrow

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25
Where do T cells mature?
Thymus
26
Where are T cells found?
Blood Lymph nodes Spleen
27
Purpose of CD3 sites on T cells
-do not bind to Ag -instead, after Ag binds to cell, CD3 site sends signal into the cell nucleus
28
What do T cells require for activation?
-2 signals -signal 1 occurs when TCR comes together with an MHC bound antigen
29
What are the 4 main types of T cell?
T helper cells - CD4+ve - help B cells are antibody, activate macrophages & natural killer cells, help development of cytotoxic T cells (help activate B cells & cytotoxic T cells) Cytotoxic T cell - CD8+ve - kill cells directly - recognise & kill infected host cells - release perforin that causes cells to lyse T regulator/suppressor cells - CD4+ve - regulate/suppress immune responses
30
TH1 vs TH2 cells
TH1 - help immune response with intracellular pathogens TH2 - help immune response with extracellular pathogens
31
What cytokines do TH1 cells produce?
IL-2 y-inteferon TNFB
32
What cytokines do TH1 cells produce?
IL-4, -5, -6, -10, -13
33
What cytokines do TREG cells produce?
IL-10 TGF-B IL-35 (down regulate other T cell subsets)
34
B lymphocytes
-major role in adaptive immunity -recognise Ag displayed by APC -differentiate into plasma cells
35
Lifespan of B lymphocytes
Hours-years
36
Where are B lymphocytes produced?
Bone marrow
37
Where do B lymphocytes mature?
Bone marrow
38
Where are B lymphocytes found?
Blood, lymph nodes, spleen
39
What is the role of plasma cells?
Produce antibodies
40
What do antibodies do?
-immunoglobulins - soluble -hallmark of adaptive immunity - they bind to a specific Ag on a pathogen -attach to pathogens -neutralise pathogen -cause opsonization & agglutination -cause phagocytosis of pathogen to occur -antibody-dependent cellular cytotoxicity -complement activation
41
Opsonization
Opsonins tag pathogens for elimination by phagocytosis
42
Antibody-dependent cellular cytotoxicity
-pathogen is coated with antibodies -white blood cell (NK cell) bind to the antibodies and release substances that kill the pathogen
43
What are B memory cells?
-plasma cells -which remain in the blood after an infection -they can produce antibodies to a specific antigen within a short amount of time if that antigen is found within the body again
44
Natural killer cells
-15% of lymphocytes -found in spleen, tissues -recognise & kill by apoptosis -kill virus infected cells & tumour cells
44
Natural killer cells
-15% of lymphocytes -found in spleen, tissues -recognise & kill by apoptosis -kill virus infected cells & tumour cells
45
What are soluble factors of the immune system?
-complement -antibodies -cytokines -chemokines
46
Complement factors
-facilitate the uptake & destruction of pathogen by phagocytic cells -mode of action = direct lysis, attract more leukocytes to site of infection, coat invading organisms -classical - Ab bound to microbe -alternative - C bound to microbe
47
What type of molecule are immunoglobulins?
Glycoproteins
48
What are the 5 classes of Igs?
IgG IgA IgM IgD IgE
49
IgG
-predominant in human serum -70-75% of total Ig in serum -crosses placenta
50
IgA
-15% of Ig in serum -predominant Ig in mucous secretions, eg. saliva, milk, bronchiolar secretions
51
IgM
-accounts for 10% of Ig in serum -mainly found in blood -large so cannot cross endothelium -mainly part of primary response - initial contact with Ag
52
IgD
-accounts for 1% of Ig in serum -a transmembrane monomeric form is present on mature B cells
53
IgE
-accounts for ~0.05% of Ig in serum -basophils & mast cells express an IgE-specific receptor that has high affinity or IgE - binding triggers histamine release -associated with allergic response & defence against parasitic infections
54
Human serum
Fluid that remains once clotting factors are removed from blood plasma
55
Definition of antibody
-Ab -protein produced in response to an antigen -can only bind with the antigen that induced its formation - specificity
56
Definition of antigen
-Ag -molecule that reacts with preformed antibody and specific receptors on T and B cells
57
Epitope
The part of the antigen that binds to the antibody/receptor binding site
58
Affinity
Measure of binding strength between an epitope and an antibody binding site - the higher the affinity the better
59
Cytokines
-proteins secreted by immune & non-immune cells -substances produced by one cell that influence the behaviour of another -> affecting intercellular communication
60
Name 4 types of cytokine
Interferons Interleukins Colony stimulating factors Tumour necrosis factors
61
Inteferons
-IFN -induce a state of antiviral resistance in uninfected cells -limit spread of viral infection
62
Interleukins
-IL -produced by many cells (over 30 types) -cause cells to divide, to differentiate, to secrete factors
63
Colony stimulating factors
-CSF -involved in directing the division & differentiation of bone marrow stem cells (precursors of leukocytes
64
Tumour necrosis factors
-mediate inflammation & cytotoxic reactions
65
Chemokines
-40 proteins that direct movement of leukocytes from bloodstream -> tissues/lymph organs -by binding to specific receptors on cells -attract leukocytes to sites of infection/inflammation
66
Types of leukocyte
Granulocytes - neutrophils, eosinophils, basophils Monocytes Lymphocytes - B cells, T cells (white blood cells)
67
What is innate immunity comprised of?
Physical & chemical barriers Phagocytic cells - neutrophils, macrophages Serum proteins - complement, acute phase
68
Innate immunity - anatomical barriers
Skin - dermis, epidermis Sebum - skin secretions Intact skin - prevents penetration, prevents growth
69
Components of mucous membranes - physical barrier
-saliva -tears - lysozyme in tears & other secretions -low pH & commensals of vagina -mucous secretions -mucous - entrapment -clila - beating removes microbes -commensal colonies - attachments, nutrients - prevent colonisation and invasion by pathogens
70
Physiological barriers to pathogens
Temperature (chickens have high body temp. - anthrax resistant) Fever - inhibits micro-organism growth -pH -gastric acidity (neonate stomach less acid than adult - susceptible to infection)
71
Inflammation
-series of reactions -that brings cells & molecules of the immune system -to the site of infection/damage
72
What is the response to a barrier being breached (tissue damage/infection)?
-stop bleeding - coagulation -acute inflammation- leukocyte recruitment -kill pathogens, neutralise toxins, limit pathogen spread -clear pathogens/dead cells - phagocytosis -proliferation of cells to repair damage -remove blood clot - remodel extracellular matrix -re-establish normal structure/function of tissue
73
Hallmarks of inflammation
-increased blood supply -increased vascular permeability -increased leukocyte trans-endothelial migration - extravasation
74
Extravasation
-discharge/escape -as of blood -from a vessel into the tissue (usually lymph from blood into tissues)
75
Acute inflammation
-complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes & full regeneration of tissue -neutrophil mediated
76
Chronic inflammation
-persistent, unresolved inflammation -macrophage mediated
77
Complement system
-cascade -comprised of a distinct number of plasma proteins which react to opsonize pathogens & induce a series of inflammatory responses that help to fight infection
78
What can C' (complement) do?
-lyse microbes directly - membrane attack complex -increase chemotaxis - migration of immune cells towards source of stimulus through detection of the direction & intensity of an extracellular chemical gradient -opsonization - C3b
79
Phagocytosis stages
1)Binding 2)Engulfment 3)Phagosome formation - pathogen digested & vesicle forms around pathogen 4)Lysosome fusion - phagolysosome - lysozymes digest pathogen material 5)Membrane disruption 6)Antigen presentation/secretion
80
What part of adaptive immunity kills intracellular microbes?
Cell mediated - T cells
81
What part of adaptive immunity kills extracellular microbes?
Humoral (Ab) - B cells
82
Major histocompatibility complex
-MHC -bind to & display peptide fragments from self or non-self proteins (eg. degraded microbial proteins) on the cell surface for recognition by appropriate T cells -invasion alert
82
Major histocompatibility complex
-MHC -bind to & display peptide fragments from self or non-self proteins (eg. degraded microbial proteins) on the cell surface for recognition by appropriate T cells -invasion alert
83
MHC I
Glycoproteins on all nucleated cells Intrinsic - Tc (CD8) - kill infected cell with intracellular pathogen
84
MHC II
Glycoproteins only on APCs Extrinsic - Th (CD4) - help B cell make Ab to extracellular pathogen
85
MHC III
Code for secreted proteins
86
Cell mediated immunity
INTRACELLULAR Interlay between APCs (macrophages, dendritic cells, B cells) and T cells -requires intimate cell to cell contact -control Ab responses via contact with B cells -directly recognise & kill viral infected cells
87
What does cell-mediated immunity require?
MHC Intrinsic (endogenous) antigens Extrinsic (exogenous) antigens Recognise self/non-self
88
Humoral immunity
EXTRACELLULAR
89
What type of Ag will T cells respond to?
Only respond to intracellular presented antigens
90
B cell activation
-B cells become activated upon binding with an antigen - a specific B cell binds to a specific antigen - the right B cell has to be selected to bind - clonal selection -then travel to the lymph nodes where clonal expansion takes place with the cells differentiating into plasma cells -plasma cells secrete Ab (usually IgM) -IgM later turn into IgG -B cells divide - clonal expansion - differentiate into plasma cells & B memory cells -re-stimulation of memory B cells lead to secondary response
91
Which cells are APC?
Dendritic cells (primary APC) Macrophages B cells
92
T cell selection
-T cells bearing autoreactive T cell antigen receptors (TCRs) are eliminated during the their development in the thymus (foetal) -these are T cells that recognise self
92
T cell selection
-T cells bearing autoreactive T cell antigen receptors (TCRs) are eliminated during the their development in the thymus (foetal) -these are T cells that recognise self

2A CLINICAL SCIENCES (14 decks)

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