Immunology Flashcards
(166 cards)
1
Q
What are the primary lymphoid organs (2)
A
bone marrow and thymus
2
Q
What happens in the primary lymphoid organs
A
Lymphocytes develop and mature
3
Q
What are the secondary lymphoid organs (2)
A
spleen and lymph nodes
4
Q
What happens in secondary lymphoid organs
A
mature lymphocytes encounter antigens, become activated, and initiate immune response
5
Q
What are the cells involved in the innate immune system (8)
A
neutrophil
Basophil
Eosinophil
Monocyte
Dendritic cell
Nk cell
Mast cell
Macrophage
6
Q
What cells are involved in the adaptive immune response (3)
A
B cell, T cell, plasma cells
7
Q
What are the anatomical and physiological barriers (5)
A
skin
Sebaceous glands
Commensalism bacteria
Mucus
Coughing + sneezing
8
Q
What does it mean if the immune response is humoral
A
It involves antibodies
9
Q
How do innate immune cells recognise pathogens
A
Via pattern recognition receptors which bind to pathogen associated molecular patterns
10
Q
Where are selectins found
A
on endothelial cells
11
Q
What do selectins do
A
facilitate rolling of immune cells which then adhere to the vessel walls
12
Q
How do immune cells arrive at the site of the infection
A
They are drawn by chemotatic signals
13
Q
How do innate immune cells recognise pathogens
A
Via their pattern recognition receptors which intersect with the pathogen associated moleculular patterns
14
Q
What modes of ingestion may occur in the innate immune response (3)
A
Pinocytosis
Phagocytosis
Receptor-mediated endocytosis
15
Q
Describe pinocytosis
A
Ingestion of the fluid surrounding cells
16
Q
A
17
Q
What does of ingestion are used in the innate immune system (3)
A
pinocytosis, receptor mediated endocytosis, and phagocytosis
18
Q
Describe phagocytosis (6)
A
PRRs bind to PAMPs, signalling the formation of the phagocytic cup
The cup extend around the target and forms a phagosome
The phagosome fuses with lysosomes (phagolysosome), this leads to killing of pathogens and degradation of contents
Debris are related into extracellular fluid
Pathogen derived peptides are expressed on cell surface receptors (MHC II)
Pro-inflammatory mediators are released
19
Q
What is pinocytosis
A
Ingestion of fluid surrounding cells
20
Q
What is endocytosis
A
molecules bound to membrane receptors are internalised
21
Q
Which method of ingestion is important for the generation of adaptive immunity
A
endocytosis
22
Q
What facilitates these modes of ingestion
A
opsonisation - coating of pathogens by soluble factors
23
Q
What do mast cells release (2)
A
pre-formed pro-inflammatory mediators (degranulation)
New pro-inflammatory mediators
24
Q
What does inflammation promote (3)
A
vascular changes
Recruitment and activation of neutrophils
Production of chemical signals to attract neutrophils
25
What are the steps of transendothelial migration (5)
migration to endothelium near affected tissue
Binding to adhesion molecules on endothelial cells
Migration across endothelium
Migration within tissue (due to chemotaxis)
Activation by PAMPs and TNFα
26
What are the physiological sings of acute inflammation (4)
redness
Heat
Swelling
Pain
27
Why is redness and heat observed in acute inflammation
Dilation of blood vessels increases blood flow, cell accumulation, and cell metabolism
28
Why is swelling a sign of acute inflammation
there is increased permeability of post-capillary venules which means that fluid accumulates in extravascular spaces
29
What methods of killing exist (2)
oxygen dependent
Oxygen independent
30
Describe degranulation (2)
release of antibacterial proteins from neutrophil granules into extracellular milieu, causing killing of pathogens and tissue damage
31
NETS (2)
A method of killing pathogens, neutrophil extracellular traps
32
How can neutrophils kills pathogens (3)
phagocytosis
Degranulation
NETS
33
What do virally infected cells produce and release
interferons (a type of cytokines)
34
What do interferons do (3)
signal to uninfected to destroy RNA
Signal neighbouring infect cells to undergo apoptosis
Activates immune cells
35
What adhesion molecule do neutrophils bind to priori to migrating across endothelium (2)
selectins, IcAM-1
36
What does the acute phase response involve (2)
changes in plasma concentration of certain proteins in response to inflammation
Production of acute phase proteins
37
What are examples of acute phase proteins (3)
c3
MBL
C reactive protein (CRP)
38
What does CRP do
Acts as an opsonin
39
What are the three pathways for activating the complement system
classical
Alternative
Lectin
40
Describe the classical pathway
IgM and IgG cause a conformational change in C1, thus activating the cascade
41
What lectin pathway for activating the complement system
mannose binding lectin binding to carbohydrates
Mimics c1 binding to immune complexes
42
What is the alternative pathway for activating the complement pathway
Spontaneous hydrolysis of c3 and its binding to bacterial cell walls
43
What happens in the complement pathway (6)
c3 convertase activation
C3 is broken down into C3a and c3b by c3 convertase
C5 convertase activation
C5a binds to c6, c7, and c8 to form the c5 convertase complex
C5 convertase complex inserts onto cell membrane
C9 binds to the complex, forming the membrane attack complex
44
How do the innate and adaptive immune systems communicate with each other
dendritic cells
45
What activates dendritic cells
pro-inflammatory mediators
46
Which immune response are B cells involved in
humoral immune response
47
Which immune response are T cells involved in
cellular immune response
48
What are the functions of C3a and C5a (2)
inflammatory mediators
Recruit phagocytes
49
Examples of complement inhibitors (5)
C1, Factor I, Factor H, C4 binding protein, CD59
50
What are the protein components of the adaptive immune system (2)
Cytokines
Antibodies
51
which is the most abundant antibody
IgG
51
Describe the regions found on antibodies
Heavy chains - have variable regions
Light chains - have constant regions
52
Which antibody is the first to be produced in an immune response
IgM
53
What else may antibodies be known as
immunoglobulins
54
Where are mature, quiescent, antigen-specific B and T cells found
constantly circulating between the blood, secondary lymphoid tissues, and lymphatic vessels
55
What type of antibody is IgA
Secretory
56
where is IgA secreted (3)
mucus, saliva, and tears
57
How do the innate and adaptive immune systems communicate
Dendritic cells
58
What activates dendritic cells
pro-inflammatory mediators
59
which immune response are B cells involved in
humoral
60
Which immune response are T cells involved in
cellular
61
Where are mature, quiescent, antigen-specific B and T cells found
circulating between the blood, secondary lymphoid tissues, and lymphatic vessels
62
which is the most abundant antibody type
IgG
63
Which antibody type is the first to be produced in a response
IgM
64
What else may antibodies be known as
immunoglobulins
65
What are the regions on antibodies
heavy chains - have variable regions
Light chains - have constant regions
66
What two functions can antibodies have
recognition - binding to the antigen
Effector - heavy chain region interacts with effector molecules
67
what does IgA do
tags the pathogen for destruction
68
What does IgD do (2)
acts as a B cell receptor
Stimulates release of IgM
69
What does IgE do
binds to mast cells and basophils
70
What does IgG do (6)
binds to phagocytes
Crosses placenta
Complement system activation
Nk activation
Agglutination
Neutralisation
71
What does IgM do (4)
acts as a B cell receptor
Secretory
Agglutination
Complement system activation
72
What is agglutination
when an antibody cross-links with multiple antigens, forming columns of antigens
A process that increases efficacy of pathogen elimination
73
What are the routes a B cell can be taken to be activated (2)
An antigen binding to the receptor then a PRR binding to a PAMP
Or multiple antigens and receptors engage, dismissing the need for a PRR
74
once activated, what happens to B cells
they clonally proliferate and differentiate into two types of effector cells
75
What are the types of effector cells that B cells can differentiate into, and what do these cells (2) do
Plasma cells (produce and secrete antigen-specific antibodies)
Memory B cells (long-life, circulate the body)
76
What antigens can T cell recognise
those presented to their receptors by MHC molecules
77
What types of T cells are they + what do these do (2)
cd4+ - regulates immune system and secretes Il-2
Cd8+ - kills infected cells
78
Which class of MHC presents to cd4+
MHC II, only expressed on professional antigen presenting cells
79
Which class of MHC presents to cd8+ cells
MHC I, expressed on every nucleic cell
80
What does MHC stand for
major histocompatibility complex
81
What are dendritic cells capable of doing (2)
Recognising and internalising pathogens/antigens
82
What compound stimulates immature dendritic cells, and what is the effect
TNFα
Increased expression of co-stimulators molecules
83
After dendritic cells have internalised and digested pathogens, what happens
They display pathogen-derived peptides on their surface in complex with MHC I/MHC II molecules
84
What do cd4+ cells secrete
Il-2
85
What does Il-2 do
stimulates cells to divide and differentiate
86
What can naive cd4+ cells differentiate into
cd4+ effector cells
87
What are the different types of cd4+ effector cells (5)
TH1
TH2
TH17
TFH
Regulatory T cells
88
What do TH1 cells do
enter affected tissue
Boost killing function of macrophages by switching on expression of NADPH oxidase genes
89
What does activation of NADPH oxidase genes allow
the macrophage’s lysosome to contain reactive oxygen species
90
What are TFH Cells (2)
Pro-inflammatory
Secrete pro-inflammatory cytokines
91
How is the immune response resolved (3)
macrophages switch from being pro-inflammatory to being anti-inflammatory
Macrophages secrete anti-inflammatory cytokines
Tissue repair occurs
92
What long-lived adaptive immune cells can be present after the immune response is resolved (4)
memory cd4+ cells
Memory cd8+ cells
Memory B cells
Long-lived plasma cells
93
Which antibody is more effective: IgG or IgM
IgG
94
What is immunisation
the process by which an individual develops immunity to a disease (deliberate or natural)
95
Vaccination
deliberate administration of antigenic material to acquire immunity to a certain disease
96
Active immunity (2)
protection by the individual’s own immune system
Permanent
97
Passive immunity
Protection transferred from another person/animal
Temporary
98
Examples of passive immunity (3)
placental antibody transfer
Antibodies in breast milk/colostrum
Venom antidotes
99
What is a hypersensitive reaction
an exaggeration of normal immune mechanisms that results in bystander damage to self
100
What is type one hypersensitivity
immediate
101
What is type two hypersensitivity
direct cell effects
102
What is type three hypersensitivity
immune complex mediated
103
what is type four hypersensitivity
Delayed
104
What stages are involved in hypersensitivity reactions (2)
sensitisation
Pathological
105
What happens during the sensitisation stage
Naive cd4+ cells are activated, converting to cd4+ TH0 cells
The receptors of mast cells and basophils combine with IgE antibodies
IgE antibodies are stabilised once bound
106
What is the pathological stage of hypersensitivity (5)
allergen binds to IgE coated mast cell/basophil
Degranulation occurs
Vasoactive mediators are released
Expression of pro-inflammatory cytokines and Leukotrienes is increased
Eosinophils are recruited and activated
107
What are the features of a type one hypersensitivity reaction (4)
immediate
More than one organ system involved
Presentation is influenced by site of contact
Threshold for reactions can be influenced by cofactors
108
What co-factors can alter the threshold for type one hypersensitivity reactions (3)
alcohol, exercise, and infection
109
What can be used to manage IgE mediated allergic reactions (6)
avoiding allergen
Anti-inflammatory agents
Adrenaline
Blocking mast cell activation
Biologics
Preventing effects of mast cell activation
110
How do biologics work
neutralise TH2 cytokines
111
What are type two hypersensitivity reactions mediated by (2)
IgM or IgG antibodies
112
What happens in a type 3 hypersensitivity reaction (4)
immune complex formed
complex passes between endothelial cells of blood vessels
Complex becomes trapped on basement membrane
Causing inflammation
113
How can an immune complex be formed
binding of multiple antigens to antibodies
114
What drives type four hypersensitivity reactions
cd4+ cells
115
What are the features of type four hypersensitivity reactions (3)
high numbers of macrophages at affected area
Symptoms take 24-48 hrs to manifest
Granulomas can form
116
Autoimmunity
immune response against self-antigens
117
What can high levels of auto-antibodies/aut0-reactive T cells cause (2)
Chronic inflammation
Tissue/organ damage
118
What are the components of T cell receptors
Alpha and beta chains
119
What allows each developing b cell to generate antibodies with a unique variable region
random selection and recombination of V, D, and J gene segments within Ig heavy and light chain genes
120
What tolerance mechanisms exist (2)
Central tolerance
Peripheral tolerance
121
Describe central tolerance
Deletion of self-reactive lymphocytes in primary lymphoid tissue during early stages of development
122
Describe peripheral tolerance
suppression of self-reactive lymphocyte activity in peripheral tissues by regulatory T cells
123
How do regulatory T cells suppress self-reactive T cells
producing anti-inflammatory cytokines
124
What causes autoimmunity
a breakdown of immune tolerance to self antigens
125
What factors can trigger autoimmunity (4)
smoking
Infections
Hormone levels
Tissue damage
126
Describe superantigens
bacterial toxins which non-specifically activate all lymphocytes (including those that are auto-reactive)
127
What are the possible responses to infection (3)
resolution
Latent infection
Chronic infection
128
What does latent infection mean
the pathogen is controlled, but infection may occur again
129
What does chronic infection mean
the immune response is defective
The pathogen is not cleared/controlled
130
What are the four signs of immunodeficiency
Serious infections
Persistent infections
Unusual infections
Recurrent infections
131
What are the two classes of immunodeficiency disorders
primary and secondary
132
What are the types of primary immunodeficiency disorders (3)
Antibody deficiency disease
T cell mediated disease
Combined immunodeficiencies
133
What are the B cell defects associated with antibody deficiency diseases (2)
reduced peripheral B cell numbers
Serum Ig levels absent/reduced
134
What are the features of antibody deficiency diseases (3)
increases susceptibility to extracellular pathogens
Growth/developmental delay
Increased incidence of autoimmune disease + malignant tumours
135
What is the pathogenesis of antibody deficiency diseases (2)
development of B cells is blocked
CD4+ TFH cell development is blocked
136
What is the defect associated with T cell mediated immunodeficiencies
reduced peripheral blood T cell numbers
137
What are the features of T cell mediated immunodeficiencies (3)
increased susceptibility to intracellular pathogens
Delayed growth/development
Increased incidence of malignant tumours
138
What is the pathogenesis of T cell mediated immunodeficiency (3)
Thymus development problems
Blocked T cell development
Associated Ig deficiencies
139
Which part of the immune system involves the gastrointestinal epithelial barrier
Innate
140
What can the gi epithelial barrier secrete (3)
cytokines
Antimicrobial peptides
MUC proteins
141
What is found at the base of a crypt
Lg5+ stem cells
142
What happens at the tip (of the crypt???)
cell shedding
143
What controls epithelial barrier growth dynamics
Signalling molecules
144
Where are immune cells found in the GI tract
lamina propria
145
What structures are found on the intestinal mucosa (2)
Peyer’s patches
Villi
146
What are the components of a Peyer’s patch (4)
Immune cells
Lymphoid tissue
Thinner mucus layer
Specialised phagocytic cells (M cells)
147
What do villi contain (3)
Lgr5+ stem cells
Loose connective tissue network (laminate propria)
148
What can M cells do
transport material across the epithelial barrier via transcytosis
149
How are antigens sampled (2)
By dendritic cells
Which extend dendrites between epithelial cells
150
What happens once dendritic cells have sampled antigens (2)
antigens are broken down and used for presentation to lymphocytes
151
what do dendrites with antigens do (2)
Go to T cell zone of a Peyer’s patch
Convert T cells to regulatory T cells
152
What do the newly formed regulatory T cells do now (3)
Go to lamina propria of villi
Via lymphatics
Then secrete Il-10
153
Il-10 function (2)
suppressing immune cell activity
Preventing unnecessary inflammation
154
what is the function of MUC proteins (3)
Forming a scaffold
Which entangled mucus produced by goblet cells
Forming a mucus layer that gives protection
155
What effect do microbes have on the epithelial barrier (2)
stimulate secretion of cytokines
Help regulate permeability
156
What effect does the epithelial barrier have on microbes (2)
determines which microbes reside in the lumen
Provides mucin (a microbial energy source)
157
Which cytokine promotes epithelial barrier repair
Il-22
158
Function of integrin (3)
directs T cells to the gut
Interacts with a complementary protein on endothelial cells
Thus slowing the cell down and causing it to move through blood vessel to tissue and be anchored
159
What does anchoring of T cells in the epithelial barrier mean
increased efficacy for longer
160
When are TH2 cells important
parasitic infections
161
What cell balance maintains gut health
T helper cells to T reg cells
162
Once anchored in the epithelium, what are T cells known as
intraepithelial lymphocytes
163
Which antibody is particularly important in the GI immune system
IgA
164
What is the definition of the microbiome
The genetic material associated with all microorganisms colonising the body
165
What is the most common mediator of sepsis
endotoxin released by gram negative bacteria
