Immunology Flashcards
1
Q
What is the immune system composed of
A
Spleen, cells, molecules (e.g antibodies)
2
Q
What does the immune system defend against
A
Infectious and inflammatory diseases, and cancer
3
Q
What are microbes
A
Viruses, bacteria, fungi, protozoa
4
Q
What is a pathogen
A
Any disease causing microbe
5
Q
What do primary lymphoid organs do
A
Produce white blood cells (lymphocytes)
6
Q
What do secondary lymphoid organs do
A
Sites where immune responses are intiated
7
Q
What are the primary lymphoid organs
A
Bone marrow and thymus
8
Q
What does the bone marrow do
A
Source of stem cells that develop into cells of the innate and adaptive immune responses
9
Q
What does the thymus do
A
School for white blood cells where they learn what they can and can’t react to, only 10% succeed
10
Q
What are the secondary lymphoid organs
A
Spleen and lymph nodes
11
Q
What does the spleen do
A
Site of initiation for immune responses against blood borne pathogens
12
Q
What do the lymph nodes do
A
Located along lymphatic vessels which drain fluid from tissues, filter lymph fluid and act as site of immune responses
13
Q
What are the three layers of defence of the immune system
A
Chemical and physical barriers, innate arm, adaptive arm
14
Q
What are the layers of the skin
A
Epidermis (dead cells, keratin, phagocytic immune cells), dermis (thick layer of connective tissue, collagen, blood vessels and phagocytic immune cells)
15
Q
What are the chemical defences of the skin
A
Antimicrobial peptides (e.g skin defensins) form pores in microbial cell membranes, lysozymes break down bacterial cell walls, sebum with low pH, hypertonic to dry out microorganisms
16
Q
What is a skin defensin
A
Antimicrobial peptide
17
Q
What are the layers of mucous membranes (1-2 layers)
A
Mucus layer, epithelium (tightly packed live cells, mucus producing goblet cells), fibrous connective tissue
18
Q
Where are mucosal membranes found
A
Lining parts of the body that lead to the outside and are exposed to air (e.g ocular, respiratory, oral, urogenital, rectal)
19
Q
What are epithelial cells in the mucociliary escalor called
A
Columnar cells
20
Q
What is the mucociliary escalator
A
Movement of mucus up to the pharynx
21
Q
What are the chemical defences of mucosal membranes
A
Stomach: low pH, gall bladder: bile, intestine: digestive enzymes, mucus: trap things, defensins, lysozyme (tears, urine)
22
Q
What makes up the innate defences
A
Surface barriers (skin, mucous membranes), phagocytes, natural killer cells, inflammation, antimicrobial proteins, fever
23
Q
What makes up the adaptive defences
A
Humoral immunity (B cells), cellular immunity (T cells)
24
Q
What are the features of the innate immune response
A
Already in place, rapid (hours), fixed, limited specificities, no specific memory
25
What are the features of the adaptive immune response
Improves during response, slow (days-weeks), variable, highly specific, long term specific memory
26
What is blood composed of
55% plasma, 45% formed elements
27
What is plasma composed of
Proteins (antibodies, immunoglobulin), other solutes, water
28
What is the formed elements part of blood composed of
Platelets, white blood cells (leukocytes), red blood cells
29
Where are blood cells sourced from
Bone marrow stem cells through hematopoiesis
30
What does the myeloid blood cell lineage give rise to
Innate immune cells
Red blood cells (erythtocytes), white blood cells (granulocytes, monocytes, dendritic cells, platelets)
31
What does the lymphoid blood cell lineage give rise to
Adaptive immune cells
White blood cells (B and T lymphocytes)
32
What are granulocytes in the blood
Type of innate immune white blood cells: neutrophils (75% of all leukocytes, highly phagocytic, numbers in blood increase during infection)
33
What are granulocytes in tissue
Mast cells which line mucosal surfaces and release granules that attract white blood cells to areas of tissue damage
34
What are the phagocytic cells in blood
Monocytes
35
What are the phagocytic cells that have left the blood (i.e develop in tissues from monocytes)
Macrophages
36
Types of macrophages
Resident (sessile), migratory
37
Functions of macrophages
Phagocytosis, release of chemical messengers, show information about pathogenic microbes to T cells (linking innate and adaptive immunity)
38
Dendritic cells
Phagocytic, found in low numbers in blood and tissues in contact with environment, most important cell type to help trigger adaptive immune responses
39
Most important cell type to help trigger adaptive immune responses
Dendritic cells
40
Which cell type links innate and adaptive immunity
Macrophages
41
How do innate cells recognise pathogens
Pathogen associated molecular patterns (PAMPs)
42
Virus PAMPs
ssRNA, dsRNA
43
Bacteria PAMPs
Cell wall: lipopolysaccharide (LPS)/endotoxins, lipoteichoic acid
Flagella: flagellin protein
Nucleic acid: unmethylated CpG DNA
44
What are toll like receptors
Receptors that bind to virus/bacteria in phagolysosome and send signal to nucleus to upregulate gene transcription of production of chemical messengers to other neighbouring cells
45
What resets the internal thermostat (hypothalamus)
Pyrogens released by cells of the immune system
46
What do phagocytes produce after ingesting bacteria
Pyrogen interleukin-1 (IL-1)
47
Why is a fever induced
Inhibits bacterial replication, some facets of the immune system work better at higher temperatures
48
What are the defensive features of the skin?
Tightly packed and constantly renewing cells, phagocytes in lower epidermis and dermis
49
Where are defensins located
Skin and mucosal membranes
50
Where are goblet cells located
Mucosal membranes, respiratory and GI tracts
51
What are granulocytes
A type of phagocyte with granules of chemicals which destroy microorganisms and play a key role in acute inflammatory reactions.
52
What are erythrocytes
Red blood cells
53
What type of cell does the myeloid lineage give rise to
Granulocytes (innate)
54
What type of cell does the lymphoid lineage give rise to
Lymphocytes
55
What type of cell does the erythroid lineage give rise to
Erythrocytes
56
What are lymphocytes
T and B cells (adaptive)
57
Name the main types of phagocytic cells
Dendritic (skin, lymph nodes, spleen), macrophage (skin, lymph nodes, spleen), neutrophil (most abundant in blood)
58
Where are TLR located and what PAMP do they recognise
Cell surface: PAMPs on surface of microbes
Phagolysosome: PAMP viral and bacterial nucleic acid
59
How is pyrexia triggered
Upregulate production of IL-1, changes hypothalamus
60
How do mast cells cause inflammation
Degranulate and produce inflammatory molecules called histamines which increase vascular permeability for chemotaxis of granulocytes (neutrophils) to get through into tissue
61
What are leukocytes
White blood cells
62
What is the most abundant leukocyte in the blood
Neutrophils
63
Name two opsonins
C3b and antibodies
64
What molecule acts on the hypothalamus to cause a fever
IL-1
65
What causes degranulation of mast cells
Complement molecules C3a and C5a
66
What do B cells do
Make antibodies
67
What do T cells do
Activate B cells
68
What causes vasodilation and increased vascular permeability of blood capillaries to let neutrophils through?
Degranulation of mast cells (tissue resident cells) releasing histamines, neutrophils follow chemical trail (chemotaxis)
69
What is the first stage of phagocytosis
Adherence (can be receptor mediated)
70
What is the second stage of phagocytosis
Engulfment: endocytosis by formation of pseudopods
71
What is the third stage of phagocytosis
Fusion: phagolysosome forms
72
What is the fourth stage of phagocytosis
Destruction: degradation of invader by digestive enzymes, reactive oxygen and nitrogen intermediates, enzymes (proteases, lipases, nucleases)
73
What is the fifth stage of phagocytosis
Exocytosis: ejection of indigestible material
74
What are the names of the three pathways leading to activation of complement
Classical, alternative, lectin
75
How does the classical pathway bind complement
Antibody bound to antigen binds complement
76
How does the alternative pathway bind complement
Pathogen binds complement to surface/pathogen component
77
How does the lectin pathway bind complement
Carbohydrate components of microbes bind complement
78
Whatever triggers the complement cascade, all end up forming
C3 convertase enzyme complex
79
How does opsonisation occur (outcome of complement activation)
C3b coats pathogen
80
How does recruitment occur (outcome of complement activation)
C3a and C5a recruit mast cells to release histamines (chemotaxis of neutrophils)
81
How does destruction occur (outcome of complement activation)
C5b, C6-C9 form membrane attack complex (MAC) which forms pores in the membrane of microbes to leach out contents and kill
82
What protein forms the majority of MACs
C9
83
How do immune cells communicate with each other
Soluble molecules, cell surface bound receptors, antigen
84
How do cytokines and chemokines work
Bind to transmembrane receptors, activate 2nd messengers to nucleus to upregulate gene transcription, cell start making proteins for immune response
85
What do helper T cells do
Support B cells in their immune response, binding alters function of one or both cells
86
Where are antigens presented to
T cell surface bound receptors, label specific virus to be responded to
87
What is specific about T cells
One type of receptor, antigen must be presented in specific way
88
What is antigen
Anything that has the potential to be recognised by the immune system (e.g foreign, self)
89
What is required to activate a T cell (activated by dendritic cells)
Chemical messenger bind to cell membrane (cytokine), cell surface bound receptors bind to T cell surface bound ligands, present antigen to cell surface bound receptors on T cells
90
What is an MHC
Major histocompatibility complex, molecule on dendritic cell surface which presents antigen to T cell
91
What is MHC-I
endogenous, intracellular antigen expressed on all nucleated cells
92
What is MHC-II
exogenous, extracellular antigen expressed only on antigen presenting cells (APCs) such as dendritic cells, macrophages, B cells
93
What is IL-1
A cytokine involved in inducing a fever by causing the hypothalamus to reset temperature
94
What is a cytokine
Interleukins and interferons that control growth and activity of immune cells: soluble chemical messengers
95
What is a chemokine
Molecules that stimulate cell migration, both produced and recognised by innate and adaptive immune cells as well as cells that influence the immune system (e.g epithelial)
96
How do T cells activate B cells (leading to it making antibodies)
Make cytokines that bind to receptors on B cell membranes, have cell surface bound receptors that bind to a B cell surface bound ligand (i.e receptor or cytokine mediated interactions)
97
How can complement activate B cells?
Complement fragments bound to antigen (classical pathway) help activate B cell to make antibodies
98
What is meant by "trigger complement"
Take inactive protein and turn into active
99
What are the main cells involved in adaptive immune response
Leukocytes: white blood cells (T and B)
100
What are lymphocytes
Type of leukocyte (WBC): T and B cells
101
What is the most potent antigen presenting cell
Dendritic cells
102
How long are peptides presented on MHC
9-15 amino acids
103
Where do dendritic cells come from
Migrate from organs to draining lymph node
104
What is antigen
Anything with potential to be recognised by the immune system
105
What are the two types of antigen
Foreign and self
106
What is the purpose of antigen uptake
Clearance of pathogens (innate) and presentation to T cells (adaptive)
107
What species have an adaptive immune response
Vertebrates and jawless fish (but based off different structures)
108
What type of antigen does MHC-1 present
Endogenous
109
What type of antigen does MHC-II present
Exogenous
110
What cells express MHC-I
All nucleated cells
111
What cells express MHC-II
APCs
112
Where are proteins degraded into peptides and loaded onto MHC-I
Degraded in cytoplasm by proteasome and loaded in endoplasmic reticulum
113
Where are proteins degraded into peptides and loaded onto MHC-II
Degraded and loaded in phagolysosome
114
What are the two types of T cells
CD4 (Helper T cells) and CD8 (Cytotoxic T cells)
115
What are the two functions of the thymus
Education of T cells, site of TCR rearrangement
116
How are T cells described after just exiting the thymus
Mature and naive
117
What does it mean if a T cell is naive
Hasn't seen antigen
118
Which parts of TCR genes rearrange
Variable (top)
119
What is the purpose of CD4 and CD8 co receptors
Ensure TCRs dock into correct MHC
120
Which T cells to MHC-I dock into
CD8
121
Which T cells to MHC-II dock into
CD4
122
What are effector T cells
Activated T cells (docked MHC peptide complex)
123
What do helper T cells help with and how
Help CD8 T cells become cytotoxic and B cells make antibody by releasing cytokines
124
What does a CD8 T cell require to be activated
Docking into MHC of APC and cytokines from CD4
125
How do cytotoxic T cells kill virally infected cells
Release perforin (poke holes in membrane) which granzyme goes through and triggers apoptosis (programmed cell death)
126
What are memory T cells
CD4 or CD8 T cells that reside in the body for long periods of time and become effector cells much faster than naive T cells (secondary response)
127
High levels of which antibody isotype indicate an effective vaccine
IgG
128
What is the purpose of apoptosis
Deprive virus of machinery to make progeny
129
How are viruses killed by the immune system
CTLs release perforin and granzyme which result in apoptosis, depriving virus machinery to proliferate
130
What characterises a secondary immune response (with regards to antibody)
Lots of class switched antibody
131
What are the three roles of antibody
Neutralisation, opsonisation and complement activation (classical pathway)
132
What is required for a B cell to be activated
Cytokines from T helper cell, binding to membrane bound ligand from T cell, binding of native antigen
133
Where do B cells complete differentiation
Bone marrow
134
What are naive mature B cells
B cells that have BCRs but have not seen antigen
135
What are plasma cells
Activated B cells that secrete antibody
136
What is humoral immunity
Antibody mediated immunity where B cells secrete antibody to affect bacteria
137
What is cell-mediated immunity
The creation of cytotoxic T cells to kill virus infected cells
138
What joins the two heavy chains of antibody
Disulphide bridge
139
Where are the variable regions of antibody
End of light and heavy chains
140
What do membrane bound antibodies have that secreted don't
A transmembrane region
141
Where are the constant regions of antibodies
The bottoms of the heavy and light chains
142
What antibody class do naive mature B cells mostly have
IgM, IgD
143
What is the name of the antibody binding site
Epitope
144
What is a native antigen
An unprocessed antigen
145
Antibodies are all in this form in blood, expect for IgM
Monomeric
146
What is the most abundant Ig class in blood
IgG
147
What are the functions of IgG
Opsonisation, neutralisation, passive immunity (crosses placenta)
148
What is the only Ig class that crosses the placenta
IgG
149
Where is IgG found
Blood
150
What is the most abundant Ig class in the secondary response
IgG
151
What is the structure of IgA
Monomer in blood, dimer on mucosal surfaces for stability (gut, lungs)
152
What are the functions of IgA
Passive immunity (breast milk) and present in blood
153
What are the two Ig types that provide passive immunity
IgG, IgA
154
What Ig class type is found on mucosal membranes
IgA
155
What stabilises multimeric forms of antibody
J chains
156
What are the primary response isotypes
IgM, IgA
157
Which isotype class sometimes exists in pentameric form
IgM
158
What is the function of IgM
BCR, when secreted good at activating complement
159
Where are IgM found
Blood and naive B cells
160
What isotype activates mast cells
IgE
161
What is the function of IgE
Immunity to multicellular parasites, allergic reactions
162
What does IgE binding to mast cells result in
Degranulation of the mast cell and release of inflammatory molecules such as histamines
163
What is the function of IgD
Acts as a BCR with IgM, specific function unknown
164
What are memory cells
Express antibody as BCR but do not secrete antibody. Respond rapidly to antigen encounter and become plasma cells
165
How long does the primary immune response take to produce sufficient antigen
7-14 days
166
What is the main Ig class produced in the primary response
IgM
167
How long does the secondary immune response take to produce sufficient antigen
2-3 days
168
What is the main Ig class produced in the secondary response
IgG with some class switching to IgA and IgE
169
What is severe combined immunodeficiency (SCID)
An X linked disease resulting in dysfunctional T and B cells
170
What does HIV target
CD4 T cells (binds to CD4 receptors)
171
Can invertebrates have autoimmune diseases
No as autoimmunity comes from adaptive immunity
172
What causes autoimmunity
Autoreactive T or B cells
173
What is rheumatoid arthritis
Autoreactive T and B cells attacking self antigens present in joints
174
What is diabetes type I
T-cell mediated attack of pancreatic islet beta cells
175
What antigens trigger allergic reactions
Allergens
175
How does the allergic response occur
Primed helper T cells activate B cells to secrete IgE, IgE binds to mast cell receptors (FcR) causing degranulation and release of histamine and other inflammatory mediators
176
Where do FcR bind to antibody
Fc region (constant)
177
What do FcR (mast cell receptors) facilitate
Phagocytosis and mast cell activation
178
What part of the antibody changes in an isotype switch
Constant Fc region
179
What is the shared property of physical barriers
Constant replacement of cells
180
How is the effectiveness of a new vaccine measured
The amount of IgG made
181
What is the usual progression of antibody class switching
IgM/D -> IgG -> IgA -> IgE
182
What is clonal selection
Selective expansion of lymphocytes that interact with antigen
183
Where are endogenous antigens broken down
In the cytosol, then proteins broken down by proteasome
184
Where does antibody class switching occur
Lymph nodes and spleen
185
Class switching does not change the ______ of the antibody, but does change the ______
Specificity, function
186
What are the 4 types of vaccine
Live attenuated, killed, sub unit protein, sub unit mRNA
187
What is a live attenuated vaccine and give an example
Less infectious version of pathogen, e.g polio-sabin, MMR
188
What is a killed vaccine and give an example
Dead pathogen, e.g polio-salk, influenza, SARS-CoV-2
189
What is a mRNA subunit vaccine and give an example
mRNA that encodes a crucial protein (produced by our own body then recognised), e.g SARS-CoV-2, pfizer
190
What is a subunit protein vaccine and give an example
Crucial/important protein, e.g tetanus, SARS-CoV-2 (spike)
191
What is an adjuvant
Immune stimulants added to vaccines that enhance the activation of APCs
192
Which vaccines normally adjuvants
Sub unit vaccines
193
How are memory B cells formed
When a B cell is activated it differentiates into some plasma cells and some memory cells
