Immunology Flashcards
0
Q
In what two ways is the immune system able to identify and eliminate harmful microorganisms and harmuf substances such as toxins?
A
- By distinguishing ‘self’ from ‘non-self’ proteins
2. By identifying ‘danger’ signals (e.g. from inflammation)
1
Q
What 4 things is the immune system for?
A
Viruses (influenza)
Bacteria (Staphylococcus)
Protozoa (amoeba)
Worms (guinea worm)
2
Q
What 5 things can result when the immune system goes wrong?
A
Recurrent infections Allergy Autoimmune disease Cancer Transplant rejection
3
Q
What is the name for exposure of an individual to the contents of dried smallpox pustules from infected patient?
A
Variolation
4
Q
What are 3 stages of the evolutionary ‘arms race’?
A
- The pathogen selects its host based on intrinsic flaws in the defensive barriers
- The host evolves to correct those flaws
- The pathogen replicates, and evolves to evade these corrections, and to exploit other flaws in the defensive barriers
5
Q
Give the route of entry, mode of transmission and pathogen causing Influenza disease
A
Route of entry - Airway
Mode of transmission - Inhaled droplet
Pathogen - Influenza virus
6
Q
Give the route of entry, mode of transmission and pathogen for Meningococcal meningitis disease
A
Route of entry - Airway
Mode of transmission - Spores
Pathogen - Neisseria meningitidis
7
Q
Give the route of entry, mode of transmission and pathogen of Inhalation anthrax disease?
A
Route of entry - Airway
Mode of transmission - Spores
Pathogen - Bacillus anthracis
8
Q
Give the route of entry, mode of transmission and pathogen for typhoid fever?
A
Route of entry - GI tract
Mode of transmission - contaminated water or food
Pathogen - Salmonella typhi
9
Q
Give the route of entry, mode of transmission and pathogen for Diarrhoea
A
Route of entry - GI tract
Mode of transmission - contaminated water or food
Pathogen - Rotavirus
10
Q
Give the route of entry, mode of transmission and pathogen for Syphillis
A
Route of entry - reproductive tract
Mode of transmission - Physical contact
Pathogen - Treponema pallidum
11
Q
Give the route of entry, mode of transmission and pathogen for AIDS
A
Route of entry - reproductive tract
Mode of transmission - Physical contact
Pathogen - HIV
12
Q
Give the route of entry, mode of transmission and pathogen for Athlete’s foot
A
Route of entry - external surface
Mode of transmission - physical contact
Pathogen - Trichophyton
13
Q
Give the route of entry, mode of transmission and pathogen for Cutaneous anthrax
A
Route of entry - Wounds and abrasions
Mode of tranmission - Minor skin abrasions
Pathogen - Bacillus anthracis
14
Q
Give the route of entry, mode of transmission and pathogen for Tetanus
A
Route of entry - wounds and abrasions
Mode of transmission - Puncture wounds
Pathogen - Clostridium tetani
15
Q
Give the route of entry, mode of transmission and pathogen for Tularemia
A
Route of entry - Wounds and abrasions
Mode of transmission - Handling infected animals
Pathogen - Francisella tularensis
16
Q
Give the route of entry, mode of transmission and pathogen for Yellow fever
A
Route of entry - Insect bites
Mode of transmission - Mosquito bites
Pathogen - Flavivirus
17
Q
Give the route of entry, mode of transmission and pathogen for Lyme disease
A
Route of entry - insect bites
Mode of transmission - Deer tick bites
Pathogen - Borrelia burgdoferi
18
Q
Give the route of entry, mode of transmission and pathogen for Malaria
A
Route of entry - insect bites
Mode of transmission - Mosquito bites
Pathogen - Plasmodium spp.
19
Q
List 5 organs/anatomical structures that protect against infection
A
- Lymph nodes
- Spleen
- Lymphatics
- Bone marrow
- Skin
20
Q
List 5 cells that protect against infection
A
- Neutrophils
- Monocytes/macrophages
- Eosinophils
- Mast cells
- Lymphocytes
21
Q
List 4 proteins that protect against infection
A
Immunoglobulins
Complement
Cytokines
Mucous
22
Q
What is the most important barrier to infection?
A
Skin
23
Q
Describe the cells that make up skin
A
Tightly packed, highly keratinised, multilayered cells
24
What is the pH of skin?
low pH 5.5
25
What other physiological factor other than pH does skin have?
Low oxygen tension
26
What glands are present in the dermis of skin?
Sebaceous glands
27
What 4 things do sebaceous glands secrete?
Hydrophobic oils
Lysozyme
Ammonia
Antimicrobial peptides
28
What do the secreted hydrophobic oils from subaceous glands do?
Further repel water and microorganisms
29
What do lysozymes secreted from sebaceous glands do?
Destroy the structural integrity of bacterial cell walls
30
What property does ammonia secreted from sebaceous glands possess?
Anti-bacterial properties
31
Give an example of an antimicrobial peptides
Defensins
32
What 4 functions or substances does secreted mucous have that provide protection?
Physical barrier
Secretory IgA
Contains enzymes: lysozymes, defensins, antimicrobial peptides and lactoferrin
Cilia
33
What does secretory IgA from secreted mucous prevent?
Bacteria nad viruses attaching to and penetrating epithelial cells
34
What do lysozymes, defensins and antimicrobial peptides do?
dIRECTLY KILL INVADING PATHOGENS
35
What does lactoferrin in secreted mucous do?
Acts to starve invading bacteria of iron
36
What two things do commensal bacteria produce?
Produce fatty acids and bactericidins that inhibit the growth of many pathogens
37
Where are commensal bacteria normally found residing?
At epithelial surfaces
38
What are 5 functions of commensal bacteria?
1. Production of bactericidins which influence other bacteria
2. Reduction in pH or large bowel
3. Competition for essential nutrients
4. Production of anti-microbial short chain fatty acids
5. Synthesis of vitamins: Vitamin K, B12
39
What anti-acid mediation can breach constituitive barriers?
Proton pump inhibitors - used in gastrooesophageal reflux and heartburn
40
What does streptococcus pneumoniae cause?
Pneumonia
41
What does Clostridium tetani cause?
Tetanus
42
What does Trypanosoma brucei cause?
Sleeping sickness
43
What does Pneumocystis carinii cause?
Pneumocystis pneumonia
44
What does Mycobacterium leprae cause?
Leprosy
45
What does Leishmania donovani cause?
Leishmaniasis
46
What does Plasmodium falciparum cause?
Malaria
47
What does Variola cause?
Small pox
48
What does Influenza cause?
Flu
49
What does Varicella cause?
Chickenpox
50
What does Ascaris cause?
Ascariasis
51
What does Schistosoma cause?
Schistosomiasis
52
Name two parasitic worms
Ascaris
| Schistosoma
53
What two arms comprise the immune system?
Innate immune system
| Adaptive immune system
54
What are of the immune system is responsible for generating the immunological memory?
Adaptive immune system
55
What two things are major components of the immune system?
Cells (Leukocytes, white blood cells)
| Soluble (humoral) factors
56
Name the 4 phagocyte cells
1. Neutrophils
2. Monocytes
3. Macrophages
4. Dendritic cells
57
Name the 3 lymphocytes
T cells
B cells
Natural Killer cells
58
What are antibodies and complement proteins?
Soluble (humoral) factors
59
What are antibodies also known as?
Immunoglobulins
60
What are proteins that are produced in response to a particular molecule and bind specifically to that antigen?
Antibodies
61
What do antibodies provide defence against?
Extracellular pathogens (most bateria), viruses and toxins
62
What has a family of approximately 30 proteins?
Complement
63
Where is complement produced?
In the liver
64
Where is complement found?
Circulating in the blood - constitue 10% of serum proteins
65
What activates pathogens directly or indirectly?
Complement
66
What does complement play a critical role in?
Inflammation and defense against certain bacterial species
67
What type of reaction is it when specific complement proteins can enzymatically activate other complement proteins in a cascade?
The complement cascade
68
Where are NK/T cell precursors found?
In the thymus
69
What cell is the precursor for ALL leukocytes?
Hematopoietic stem cell
70
What 3 cell progenitors does the hematopoietic stem cell produce?
Common lymphoid progenitor
Common myeloid progenitor
Common erythroid megakaryocyte progenitor
71
What does the common lymphoid progenitor divide into?
NK/T cell precursor
| B cell
72
What does the NK/T cell precursor split into?
T cell
| NK cell
73
What two precursors does the common myeloid progenitor divide into?
Common granulocyte precursor
| Unknown precursor
74
What 3 cells does the common granulocyte precursor produce?
Neutrophil
Basophil
Eosinophil
75
What does the unknown precursor from the common myekoid progenitor divide into?
Monocyte and mast cell
76
What two cells are derived from monocytes?
Dendritic cells and macrophages
77
What does the common erythroid megakaryocyte progenitor divide into?
Megakaryocyte and erythroblast
78
What is derived from megakaryocytes?
Platelets
79
What is derived from erythroblasts?
Erythrocytes
80
What cells reside in tissues and protect mucosal surfaces?
Mast cells
81
What two cells circulate the blood and are recruited to sites of infection by inflammatory signals?
Basophils and Eosinophils
82
What do mast cells, basophils and eosinophils all release?
Chemicals such as histamine, heparin and cytokines
83
What do mast cells, basophils and eosinophils all have a key role in?
Mediating allergic responses
84
What type of cells are macrophages, neutrophils and dendritic cells?
Phagocytes
85
In addition to phagocytosis what do phagocytic cells also do?
Clear debris from dead/dying tissue cells
86
What are macrophages, neutrophils and dendritic cells an important source of?
Cytokines which promote an acute inflammatory response
87
What are also known as polymorphonuclear cells (PMNs)?
Neutrophils
88
What are circulating monocytes precursors of?
Tissue-resident macrophages
89
What are the 3 additional functions of monocytes and macrophages?
1. Help limit inflammation
2. Involved in tissue repair and wound healing
3. Involved in antigen presentation
90
What do dentritic cells present as in peripheral tissues?
Immature cells
91
When met by a pathogen what happens to immature dentritic cells?
They mature and migrate into secondary lymphoid tissues and stimulate adaptive immune responses (antigen presentation)
92
What type of cells are large granular lymphocytes, can kill tumour cells and virally infected cells and can also kill antibody-bound cells/pathogens?
Natural Killer cells
93
How do natural killer cells kill some virus-infected cells?
Release lytic granules
94
What three areas or substances are T and B cells found in?
Constantly circulating through the blood, lymph and secondary lymphoid tissues
95
Are T and B cells inactive or active before meeting pathogens/antigens?
Inactive
96
What cells are responsible for the production of antibodies?
B cells
97
What cells have a key role in defense against intracellular pathogens (viruses, mycobacteria)?
T cells
98
What are the two sub-catagories of T cells?
Helper T cells
| Cytotoxic T cells
99
What are helper T cells?
Key regulators of the entire immune system
100
What can cytotoxic T cells do?
Kill virally infected body cells
101
What are the sites of leukocyte development?
Primary lymphoid tissues
102
Where are adaptive immune responses initiated?
Secondary lymphoid tissues
103
What system of vessels drains fluid from the body tissues?
Lymphatic system
104
What removes pathogens and antigens from lymph?
Lymph nodes
105
What are the two distinct mechanisms of communication in the immune system?
Direct contact and indirect contact
106
What does direct contact involve?
Receptor:ligand interactions
107
What does indirect communication involve?
Production and secretion of cytokines
108
Give three examples of Receptor:ligand interactions involved in direct contact
1. MHC : TCR
2. CD40 : CD40L
3. TLR4: LPS
109
What are a diverse collection of small proteins and peptides?
Cytokines
110
What are cytokines produced in response to?
Infection, inflammation and tissue damage
111
What is the name of the form of signalling where the target cell is near the signal-releasing cell?
Paracrine signalling
112
What type of signalling is when a cell secretes a hormone or chemical messenger and it binds to autocrine receptors on the same cell.
Autocrine signalling
113
What type of function do interferons have?
Anti-viral functions
114
Name 4 types of cytokines?
Interferons
Tumour necrosis factor
chemokines
interleukins
115
What are anti-TNF drugs used in and what kind of affect do they have?
Rheumatoid arthritis - anti-inflammatory effect
116
What cytokines control and direct cell migration?
Chemokines
117
What is interleukin 2 involved in?
T cell proliferation
118
What is interleukin 10 involved in?
Anti-inflammatory
119
How does the innate immune system respond to infection?
Mast cells, NK cells, Phgocytes and complement, take part in acute inflammation and killing of pathogen
120
What are the 6 symptoms of acute inflammation?
1. Redness
2. Heat
3. Swelling
4. Pain
5. Loss of function
6. Fever
121
What is rubor?
Redness
122
What is calor?
Heat
123
What is tumor?
Swelling
124
What is dolor?
Pain
125
What is functio laesa?
Loss of function
126
During acute inflammation what happens to small blood vessels?
Dilatation and increased blood flow through the region
127
During acute inflammation, what happens to the permeability of post-capillary venules?
Increased permeability and accumulation of fluid in the extracellular space
128
Name 2 chemical mediators that stimulate nerve endings during acute inflammation?
Bradykinin and histamine
129
Where are pattern-recognition receptors (PRRs) found in innate immune cells?
```
Cell surface (extracellular pathogens)
Intracellular (intracellular pathogens)
```
130
What structures are recognised by innate leukocytes?
Pathogen-associated molecular patterns (PAMPs)
131
Name 4 pattern-recognition receptors (PRRs)?
```
Toll-like receptor 4 (cell surface)
Dectin 1 (cell surface)
NOD2 (intracellular)
Toll-like receptor 7(intracellular)
```
132
Name 4 pathogen-associated molecular patterns (PAMPs)
Lipopolysaccharide (LPS) - gram -ve bacteria
B-glucans - fungi
Muramyl dipeptide - M. tuberculosis
ssRNA - viruses
133
What is the PAMP for TLR-4?
LPS - Lipopolysaccharide
134
What is the PAMP for Dectin 1?
B-glucans
135
What is the PAMP for NOD2?
Muramyl dipeptide
136
What is the PAMP for TLR-7?
ssRNA
137
What happens when physical barriers are breached by a pathogen?
Tissue resident innate immune are activated (mast cells and macrophages)
138
What to mast cells initiate?
Acute inflammatory responses
139
What two activites do mast cells do when activated by a pathogen?
Degranulation and Gene expression
140
When mast cells degranulate what two substances are released?
Histamine
| Tryptase
141
What 3 substanes are produced in relation to gene expression of mast cells?
1. TNF
2. Chemokines
3. Leukotrienes
142
What substance released from mast cells increases vascular permeability, vasodilatation, activates endothelial cells and causes pain?
Histamine
143
What is tryptase?
A proteolytic enzyme
144
What substance from mast cells increases vascular permeability and activates endothelial cells?
TNF
145
What from mast cells attracts other innate immune cells (neutrophils and NK cells)?
Chemokines
146
What from mast cells is involved in smooth muscle contraction and increased vascular permeability?
Leukotrienes
147
What are anti-leukotrienes used in?
Asthm,a
148
What cells are professional phagocytes?
Macrophages
149
What occurs one a macrophages has PAMP : PRR binding?
Phagocytosis
150
What occurs once a macrophage has been activated by phagocytosis?
Inflammatory cytokine release
151
What cells are involved in MHC-II expression and antigen presentation?
Macrophages
152
What pro-inflammatory cytokines and anti-inflammatory cytokine do activated macrophages release?
IL-1, IL-6, TNF
| IL-10
153
What do the pro-inflammatory cytokines released from activated macrophages do to the liver?
Increase acute phase proteins
154
What do pro-inflammatory cytokines released from activated macrophages do to bone marrow and vasculature? (3 things)
Increased vascular permeability
Activation of endothelial cells
Neutrophil mobilisation
155
What do pro-inflammatory cytokines released from activated macrophages do to the hypothalamus?
Cause a fever
156
What does a fever decrease?
Pathogen replication
157
What does increased vascular permeability, activation of endothelial cells and neutrophil mobilisation increase?
Phagocytosis
158
Give 3 examples of acute phase proteins produced in the liver in response to infection, trauma or chronic inflammation
1. C-reactive protein (CRP)
2. Complement proteins (C3, C4, mannose-binding lectin)
3. Serum amyloid A
159
What does the production of serum amyloid A increase?
Phagocytosis and complement activation
160
What does serum CRP levels <10 mg/L mean?
Normal
161
What does serum CRP levels of 10-40 mg/L mean?
Mild inflammation
| Viral infections
162
What does serum CRP levels of 40-200 mg/L mean?
Active inflammation
| Bacterial infections
163
What does serum CRP levels of >200mg/L mean?
Severe bacterial infections
| Burns
164
Name 3 secondary lymphoid tissues?
Spleen
Lymph nodes
Mucosal-associated lymphoid tissues (various)
165
Name 2 primary lymphoid tissues?
Thymus
| Bone marrow
166
Name 5 pro-inflammatory mediators from mast cells and macrophages?
```
Histamine
TNF
IL-1
IL-6
Chemokines
```
167
What two things cannot be easily phagocytosed?
Parasites and viruses
168
What three things are recruited into sites of inflammation as a result of pro-inflammatory mediators?
Neutrophils, NK cells, complement protein
169
What stimulates the bone marrow to produce more monocytes and neutrophils (neutrophilia)?
Pro-inflammatory mediators
170
What do activated endothelial cells express at sites of inflammation?
Adhesion molecules (selectins and ICAMs)
171
What are selectins and ICAMS?
Adhesion molecules
172
What allows leukocytes to bind weakly (tether) to endothelial cells and roll slowly along the endothelial cell surface?
Selectins
173
What activates leukocytes?
Chemokines
174
Activated leukocytes bind strongly to endothelial cells via what?
Integrins (on the leukocytes) that bind to ICAMs (on the endothelium)
175
What do integrins bind to?
ICAMs on the endothelium
176
What do leukocytes on the endothelium do to resist shear flow and look for a suitable place to leave the blood vessel?
Flatten and crawl
177
What is the name for leukocytes squeezing between endothelial cells?
Transendothelial migration
178
Once inside tissues, how do leukocytes get to the site of infection/inflammation?
Follow a chemokine gradient
179
What does defective transendothelial migration lead to?
Leukocyte adhesion deficiency
180
What is the name of a very rare genetic disease caused by loss or reduced amounts of B2-integrins?
Leukocyte adhesion deficiency
181
What 4 components of plasma can also leak out into tissues?
Complement proteins
Kinins
Coagulation factors
Fibrinolytic system
182
What are the 3 mechanisms by which neutrophils directly attack pathogens?
Phagocytosis
Release of anti-microbial peptides and degradative proteases
Generate extracellular traps (NETs)
183
Name three things that lysosomes inside neutrophils have?
Toxic reactive oxygen species (ROS)
Hydrolytic enzymes
Acidic pH
184
Where does oxidative killing by phagocytes occur?
In phagolysosomes
185
During oxidative killing by phagocytes: what changes oxygen to superoxide?
NADPH oxidase
186
During oxidative killing by phagocytes: what changes H2O2 into HClO?
Myeloperoxidase (Fe2+)
187
What colour are Fe2+ ions?
Green
188
What does HClO do?
Kills bacteria
189
Activated neutrophils also produce TNF, what does this do?
Positive feedback promoting more inflammation
190
What does the process of phagocytosis deplete?
Neutrophil energy stores (glycogen)
191
What 3 things is pus composed of?
Dead and dying neutrophils + tissue cells + microbial debris
192
Name a phagocyte deficiency disease?
Chronic granulomatous disease
193
Some clinical features of phagocyte deficiency diseases include recurrent bacterial and fungal infections, name 4 of these
Staphylococcus Aureus and enteric bacteria
Mycobacteria: TB and atypical mycobacterial infection
Candida albicans
Aspergillus
194
What do NK cells release which enhances macrophage killing activites?
Interferon-gamma
195
What do the classical pathway, lectin pathway and alternative pathway of complement all lead to?
The conversion of C3 to C3b + C3a
196
What do C3b + C3a ultimately lead to?
The destruction of pathogens
197
During the alternative complement pathway, what is created from the binding of factor B to C3b and the activation of factor D?
What does the enzyme produced then do?
Active protease C3 convertase
This enzyme cleaves C3 to for C3b which can go on to form C5 activating convertase.
198
What does the alternative complement pathway involve?
Pathogen surfaces
199
What does the Lectin complement pathway involve?
Lectin binding to pathogen surfaces
200
What does the classical complement pathway involve?
Antigen:antibody complexes
201
In order to activate the lectin pathway, what does Mannose-binding lectin in the blood do?
Binds to a protein called MASPs
202
Once binded with MBL, what does MASP do?
Converts C3 into C3a and C3b
203
During the lectin pathway, after the clipping of C3 to C3b and C3a, what does the C3b go on to do?
Bind to the surface of the bacterium
204
how does C3b continue the complement cascade?
It combines with C5b and C5a (from C5), which then all combines with C6 - C9 and forms the membrane attack complex
205
What does the membrane attack complex do?
Destroys pathogens
206
What are the 5 effector functions of complement?
```
Membrane attack complex
Opsonisation
Chemotaxis
Clearance of immune complexes
Inflammation
```
207
What is the coating of microorganisms by immune proteins (opsonins) called?
Complement-mediated opsonisation
208
What are the 3 opsonins involved in complement mediated opsonisation?
C3b
CRP
Antibodies
209
What do phagocytes express omn their cell surface for opsonins?
Receptors
210
What process does opsonisation enhance?
Phagocytosis
211
What complement is involved in the immune complex solubilisation?
C3b
212
In complement-mediated immune complex solubilisation, what does C3b binding do?
Dissolves antibody-antigen immune complexes which are then cleared by phagocytes
213
During complement-mediated lysis, what binds to the surface of pathogens?
C5b
214
What assembles with C5b to form the membrane attack complex?
C6, C7, C8 and C9
215
Once the membrane attack complex has inserted into target cell walls - what occurs?
Osmotic cell lysis of pathogen
216
During complement-mediated inflammation and chemotaxis, what 2 substances bind to receptors on mast cells/basophils?
C3a and C5b
217
During complement-mediated inflammation and chemotaxis, once the basophils and mast cells have been activated what do the following released granules secrete?
Vasoactive substances like histamine
| Chemokines
218
What can be said about the amplification loop of the complement cascade?
It is potent
219
How is the complement cascade regulated, in terms of activated conplement proteins?
Only cleaved complement proteins
220
What can be said about the half-life of active complement proteins?
Very short
221
Name 4 complement inhibitors?
C1 inhibitor
Factor I
Factor H
C4 binding protein
222
What disease is associated with C3 and factor B complement deficiency?
Severe bacterial infections
223
What disease is associated with C3b-INA, C6 and C8 complement deficiency?
Severe Neisseria infections
224
What disease is associated with deficiencies of early C components C1, C2, C4?
Systemic lupus erythematosus (SLE), glomerulonephritis and polymyositis
225
What disease is associated with C1-inhibitor complement deficiency?
Hereditary angiodema
226
What are adaptive immune responses induced by?
Antigens
227
What the name of any substance which can cause an adaptive immune response by activating B cells and T cells?
Antigen
228
What thing do antigens contain very different types of?
Antigenic epitopes
229
How do T cells and B cells recognise antigens?
With T cell antigen recptors (TCR)
| With B cell antigen receptors (BCR)
230
What is a membrane-bound protein heterodimer with an alpha and beta chain?
T cell antigen receptor
231
What is a membrane bound antibody (IgM or IgD) with a light and heavy chain connected by disulphide bridges?
B cell antigen receptors
232
What does each heavy and light chain on an antibody contain?
A variable region and a constant domain
233
What do variable regions of an antibody form?
Antigen binding site
234
What do antibodies differ in?
Different heavy chain constant region
235
What are proteins encoded for by?
Genes
236
What are antibody heavy and light chain proteins in B cells encoded for by?
Segmented genes in the germ-line genome of haematopoietic stem cells
237
Where do adaptive immune responses occur?
In secondary lymphoid tissues
238
What do T cells and B cells used to enter lymph nodes?
Transendothelial migration
239
Antigens entering lymph nodes is a complex process. What is the first step involved?
Particles and antigens derived from pathogens are released by phagocytes.
240
Once antigen particles have been released by phagocytosis in the process of antigens entering lymph nodes, what occurs?
Inflammatory TNF stimulates immature tissue-resident dendritic cells to express B7
241
During the process of antigens entering lymph nodes, what occurs once the dentridic cells have expressed B7?
Dendritic cells phagocytose pathogen-derived particles and antigens
242
During the process of antigens entering lymph nodes, what occurs one dentritic cells have phagocytosed pathogen-derived particles and antigens?
Dentritic cells digest pathogen-derived proteins and display small peptides on the surface in complex with MHC proteins in a process known as antigen presentation.
243
During the process of antigens entering lymph nodes, what occurs once pathogen-peptides have been presented on MHC on dendritic cell surfaces?
Pathogen-derived particles, antigens and mature dendritic cells travel to local draining lymph nodes
244
Where are stromal cells found?
In B cell zones
245
What do stromal cells in B cell zones do to antigens?
Trap opsonised antigens
246
What kind of receptor do stromal cells have on their surface?
C3b receptors for C3b opsonised antigens
247
How many signals does B cell activation require?
2
248
What 2 signals do B cells require when they encounter protein antigens?
BCR + antigen
| T cell help
249
What 2 signals do B cells required when they encounter any antigen?
BCR + antigen
| PRR + PAMP
250
What 2 signals do B cells require when they encounter antigens with repetitive antigenic epitopes?
Multiple BCRs + antigens engaged (signals 1 + 2)
251
What do peptide antigens have to be presented by to be recognised by T cells?
MHC
252
What can MHC proteins also be referred to as?
HLA (human leucocyte antigens)
253
What are the two classes of MHC proteins?
Class I MHC and Class II MHC
254
What are Class I MHC proteins expressed on?
All nucleated cells
255
What type of T cell do class I MHC proteins present peptide antigens to?
Cytotoxic T cells (CD8)
256
What are class II MHC proteins expressed on?
Only professional antigen prsenting cells such as dendritic cells, macrophages and B cells
257
What type of T cell do class II MHC proteins present peptide antigens to?
Helper T cells (CD4)
258
How many signals does T cell activation require?
2
259
What are the two signals required for T cell activation when a dendritic cell presents a peptide antigen?
Signal 1: MHC peptide - TCR
| Signal 2: B7 - CD28
260
What happens after B cells have been activated?
They enter the cell cycle and mitose for clonal expansion
261
What two cells do activated B cells differentiate into?
```
Plasma cells (effector B cells) - antibodies
Memory B cells
```
262
Name a low affinity, antigen-specific antibody?
IgM
263
Name 4 high affinity, antigen-specific antibodies
IgG
IgA
IgE
IgD
264
What is the most abundant immunoglobulin in plasma and is actively transported across the placenta?
IgG
265
What antibody is a surface bound monomer = BCR, the first immunoglobulin type produced during an immune response and present only in plasma/secretions as a pentamer?
IgM
266
What antibody has extremely low levels in blood and is surface bound = BCR?
IgD
267
What antibody has extremely low levels normally and is produced in response to parasitic infections and allergic response?
IgE
268
Which antibody is the 2nd most abundant, its monomeric form is in blood and dimeric form is in breast milk, aliva, tears and mucosal secretions?
IgA
269
Which two antibodies provide protection to babies from mothers?
IgG (placenta)
| IgA (breast milk)
270
Where the Fc region found in an antibody?
In the constant region
271
What function does the variable region of an antibody have?
Recognition function - binding to antigen mediated by variable region sites
272
What function does the constant region of an antibody have?
Effector function - clearance mechanisms mediated interaction of by Fc region with effector molecules.
273
What two things does the Fc region of an antibody react with?
Complement and Fc receptors
274
What is agglutination?
Immune complex formation
275
What does binding of high affinity neutralising antibodies to antigens prevent?
Prevent viruses from infecting host cells
| Prevent microbial toxins from disrupting normal cell function
276
What two conformations does IgM have?
Planar and Staple
277
What do phagocytes express that bind to the constant region of immunoglobulins?
Fc receptors
278
What is the name of the process in which antibodies help stimulate natural killer cells?
Antibody-dependent cell-mediated cytotoxicity (ADCC)
279
During antibody-dependent cell-mediated cytotoxicity, What receptors on NK cells recognise the bound antibody?
Fc receptors
280
During antibody-dependent cell-mediated cytotoxicity, what signals the NK cell to kill the target cell?
Cross-linking of Fc receptors
281
Which antibody is involved in opsonisation?
IgG
282
Which antibody is associated with Fc receptors, mast cells and allergic responses?
IgE
283
Which antibody is the predomionant antibody class of a primary response to antigen?
IgM
284
Which 2 antibodies are involved in neutralisation?
IgG and dimeric IgA
285
Which 2 antibodies are involved in agglutination?
IgM and IgG
286
Which 2 antibodies are involved in complement activation?
IgG and IgM
287
Which antibody activates natural killer cells?
IgG
288
Which antibody activates mast cells?
IgE
289
Which two antibodies are involved in B cell activation?
IgM and IgD (surface monomer)
290
Name 2 resting T cells?
CD4+ and CD8+
291
Name the effector T cell of CD4+
T helper cells
292
Name the effector cell of CD8+?
Cytotoxic T cells
293
Once a CD4+ cell has met a dendritic cell what does the T cell convert to and what does it then do?
T helper cell
Calls for help (CD8+ cells, macrophages and B cells)
294
Which interleukin is involved in T helper cells helping CD8+ cells turn into cytotoxic T cells?
Interleukin-2
295
Where do effector Th cells migrate to and from?
From lymph node to sites of inflammation/infection
296
Once Th cells have migrated into the site of infection from the lymph node, how are they re-activated?
By macrophages in an antigen-specific manner
297
How do Th cells ultimateley help macrohpages?
They hyper-activate macrophages, enhancing their killing activites and pro-inflammatory responses
298
What ligand : receptor communcation occurs between a Th cell and a macrophage?
CD40L : CD40 (CD40L on Th cell and CD40 on macrophage)
299
During the process of Th cells help B cells respond effectively to protein antigens, what is the first step?
Protein antigen bound to BCR is internalised by teh B cell. The antigen is degraded and peptides are presented on the B cell surface in complex with MHC-II.
300
During the process of Th cells helping B cells respond to antigen proteins, What is the second stage - after the antigen is presented on the B cell surface in complex with MHC-II?
Effector Th cells move into B cell zone of the lymph node where they are re-stimulated by B cells in an antigen-specific manner and start to express CD40L. Re-activated effector Th cells stimulate the B cell to proliferate and survive via (CD40L : CD40 interactions)
301
During the process of Th cells helping B cells respond effectively to protein antigens, What is the third step - after the Th cell has stimulated B cell to proliferate and survive?
The effector Th cells secrete cytokines which further activate the B cell
302
Which 3 cytokines does the effector Th cell release to further activate B cells?
IL-5, IL-4 and IL-13
303
What are the 4 steps in the germinal centre reaction?
1. B cell proliferation
2. Antibody heavy chain switching
3. Generation of high affinity antibodies
4. Differentiation into plasma and memory B cells
304
What is somatic hypermutation?
The generation of high affinity antibodies
305
What is the aim of the generation of high affinity antibodies?
To produce antibodies that recognise the same antigen but with increased affinity
306
What method of killing do cytotoxic T cells kill infected host cells by?
Apoptosis
307
Which cells use Fas ligand mediated killing?
Cytotoxic T cells
308
Name three proteins in lytic granules of cytotoxic T cells
Perforin
Granzymes
Granulysin
309
How does the protein perforin act on target cells?
Polymerises to form a pore in target membrane
310
Which protein in lytic granules of cytotoxic T cells is a serine protease which activates apoptosis once in the cytoplasm of the target cell?
Granzymes
311
How does the protein Granulysin act on target cells?
Induces apoptosis
