Immunology Flashcards
(195 cards)
1
Q
What is innate immunity?
A
Instinctive, non-specific, doesn’t depend on lymphocytes, present from birth
2
Q
What is adaptive immunity?
A
Specific acquired/learned immunity, requires lymphocytes, antibodies
3
Q
What forms haematocrit?
A
Erythrocytes and platelets
4
Q
What is serum?
A
Plasma without fibrinogen and other clotting factors
5
Q
What are the groups of leukocytes?
A
- Lymphocytes
- Phagocytes
- Auxiliary cells
6
Q
What cells are phagocytes?
A
- Mononuclear phagocyte
- Neutrophil
- Eosinophil
7
Q
What cells are auxiliary cells?
A
- Basophil
- Mast cell
- Platelets
8
Q
What do leukocytes derive from?
A
Multipotent haematopoietic stemm cells
9
Q
What are the dendritic cells in the liver and skin?
A
Liver - Kupffer
Skin - Langerhans
10
Q
What are the modes of action of complement C?
A
- Direct lysis
- Attract more leukocytes to site of infection
- Coat invading organisms
11
Q
What are the 5 classes of immunoglobulins?
A
IgA, IgG, IgM, IgD, IgE
12
Q
What does the Fc region bind?
A
Receptors on leukocytes
13
Q
What does the Fab region bind?
A
Bind to different specific antigens
14
Q
What is the most prominent Ig?
A
IgG
15
Q
How many binding sites does IgG have?
A
2
16
Q
How many binding sites does IgM have?
A
10
17
Q
Where is IgM found?
A
Blood
18
Q
What is IgA the prominent Ig in?
A
Mucous secretions
19
Q
What cells express an IgE specific receptor?
A
Basophils and mast cells
20
Q
What is released when basophils and mast cells bind an antigen?
A
Histamine
21
Q
What are cytokines?
A
Proteins secreted by immune and non-immune cells
22
Q
What is the function of interferons?
A
To induce a state of antiviral resistance in uninfected cells and limit spread of viral infection
23
Q
What releases IFNa+B?
A
Virus infected cells
24
Q
What releases IFNy?
A
Activated Th1 cells
25
What have a switch to turn off the immune response?
Interleukins
26
What is the function of interleukins?
To cause cells to divide, differentiate and to secrete factors
27
What is the function of colony stimulating factors?
To direct division and differentiation on bone marrow stem cells
28
What is the function of tumour necrosis factors?
Mediate inflammation and cytotoxic reactions
29
What are chemokine?
Group of proteins that direct movement of leukocytes from bloodstream into tissues or lymph organs by binding to specific receptors on cells
30
What is innate immunity composed of?
1. Physical and chemical barriers
2. Phagocytic cells
3. Blood proteins
31
What are the steps of the inflammatory response?
1. Coagulation
2. Acute inflammation
3. Kill pathogens, neutralise toxins, limit pathogen spread
4. Phagocytosis
5. Proliferation of cells to repair damage
6. Remove blood clot
7. Re-establish normal function of tissue
32
What is inflammation?
A series of reactions the brings cells and molecules of immune system to sites of infection or damage
33
What are the hallmarks of inflammation?
1. Increased blood supply
2. Increased vascular permeability
3. Increased leukocyte trans endothelial migration extravasation
34
What is acute inflammation?
Complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes and full regeneration of tissue
35
What is chronic inflammation?
Persistent, unresolved inflammation
36
What do pattern recognition receptors bind?
Pathogen associated molecular patterns (PAMPs)
37
What are the functions of complement?
1. Lysis
2. Chemotaxis
3. Opsonisation
38
What are the activation pathways for C'?
1. Classical
2. Alternative
3. Lectin
39
What is the function of TNFa released by macrophages in extravasation?
Activates endothelium to make it sticky and secretes chemokines
40
What happens following chemokine secretion in extravasation?
Chemokine sticky to endothelium surface and cause neutrophil to stop on surface
41
What happens once the neutrophil is bound to the surface in extravasation?
It squeezes through endothelial cell gaps and moves to the site of infection
42
What are the steps of phagocytosis?
1. Binding
2. Engulfment
3. Phagosome formation
4. Phagolysosome
5. Membrane disruption/fusion
6. Phagocytes internalise and kill invading organisms
43
What are the 2 killing pathways in neutrophils and macrophages?
1. O2 dependent
| 2. O2 independent
44
Describe adaptive immunity
1. Antigen specificity and diversity
2. Immunological memory
3. Specific self/non-self recognition
45
Why does cell-mediated immunity require cell to cell contact?
1. To control Ab responses via contact with B cells
| 2. To directly recognise and kill viral infected cells
46
Where are T cells killed in T cell selection?
Foetal thymus
47
How do T cells recognise antigens?
1. MHC molecule presents peptide
2. Antigen peptide bound to MHC molecule
3. TCR recognises MHC and peptide
48
What codes for MHC in humans?
Human leukocyte antigen genes
49
Where are Class I MHC found?
All cells
50
Where are Class II MHC found?
Antigen presenting cells
51
What is the function of CTL?
Forms proteolytic granules, releases perforins and granulysin, induces apoptosis
52
What Ig are expressed on B cells?
IgM and IgD
53
How do B cells present antigens to T cells?
Via MHC II
54
What happens when Th2 bind to B cells?
They secrete cytokines
55
What happens when cytokines are released?
They cause B cells to divide - clonal expansion
56
What do B cells differentiate into after clonal expansion?
Plasma cells and memory B cells
57
What Ig do plasma cells tend to secrete?
IgM
58
What is it called when IgM change to IgG?
Class switching
59
How do antibodies work?
1. Neutralise toxins by binding to it
2. Increase opsonisation
3. Activate complement
60
What rate of vaccination uptake is needed for herd immunity to work?
95%
61
What is the pathway in antibody production?
Antigen -> B lymphocytes -> plasma cells -> soluble Ab
62
What class of glycoprotein do antibodies belong to?
Immunoglobulins
63
What part of the antibody is responsible for antigen recognition?
Fab region - variable in sequence
64
What part of the antibody is responsible for antigen elimination?
Fc region - constant in sequence
65
What are the 2 chains that make up constant regions and their size?
Light chain - 25kD
| Heavy chain - 50kD
66
What encodes variable and constant regions?
Exons
67
What are the 5 classes of immunoglobulin?
IgG, IgM, IgA, IgD, IgE
68
What is the main Ab class in serum and tissues?
IgG
69
What response types are IgG important for?
Secondary/memory responses
70
What response type are IgM important for?
Primary responses
71
What Ab type protects mucosal surfaces?
IgA
72
Which Ab type are involved in allergic reactions?
IgE
73
What are the 2 types of light chain?
Kappa and lambda
74
How can Ab protect against infection?
1. Specific binding/ multivalency (Fab)
| 2. Enhance innate mechanisms (Fc)
75
How do Fab regions protect against infection?
1. Neutralise
2. Immobilise motile microbes
3. Prevent binding to, and infection of host cells
4. Form complexes
76
How do Fc regions protect against infection?
1. Activate complement
| 2. Bind Fc receptors
77
What are the Fc receptors and what do they do?
1. Phagocytes - enhance phagocytosis
2. Mast cells - release inflammatory mediators
3. NK cells - enhanced killing of infected cells
78
What controls behaviour of leukocytes?
Cytokines
79
What is the role of T cells?
To specifically kill infected host cells
80
What are the T cells in immunity?
1. T helper cells
2. T cytotoxic cells
3. T regulatory cells
81
What are the functions of T helper cells?
1. Help B cells make antibodies
2. Activate macrophages and natural killer cells
3. Help development of cytotoxic T cells
82
What is the function of T cytotoxic cells?
Recognise and kill infected host cells
83
What is the function of TREGS?
Suppress immune responses
84
How are different T cell receptor (TCR) specificities achieved?
Multiple V region axons in genome recombine during T cell differentiation
85
What do B cells recognise?
Soluble, free, native antigens
86
What do T cells recognise?
Cell-associated, processed antigens
87
What has a major role in initiating T cell responses?
Major histocompatibility complexes (MHC)
88
Why are MHC described as polymorphic?
They have many different alleles at each gene locus
89
Which MHC is expressed by all nucleated cells?
MHC I
90
What do MHC I display antigens to?
Cytotoxic T cells
91
What expresses MHC II?
Macrophages, dendritic cells, B cells
92
What do MHC II display antigens to?
Helper T cells
93
How do activated T cytotoxic cells kill infected cells?
Induce apoptosis
94
What are cytokines?
Small secreted proteins involved in communication between cells of immune response
95
How do cytokines act?
Bind to specific receptors on surface of target cells
96
Give 4 types of cytokine
1. Interleukins
2. Interferons
3. Chemokines
4. Colony stimulating factors
97
What cytokines do TH1 cells make?
IL2, gamma-interferon, TNFb
98
What cytokines do TH2 cells make?
IL4, 5, 6, 10, 13
99
What cytokines do TREGS make?
IL10, TNFb
100
What do TH1 cells promote?
Production of cytotoxic T cells
101
What are TH1 cells important for?
Intracellular infections
102
What do TH1 cells induce B cells to make?
IgG
103
What do TH2 cells activate?
Eosinophils and mast cells
104
What are TH2 cells important for?
Helminth infections and allergy
105
What do TH2 cells induce B cells to make?
IgE
106
What is the counter regulation hypothesis?
Infection protects against allergy by promoting IL10 and TGFb production
107
What is the hygiene hypothesis?
Insufficient exposure to certain types of infection skews TH1/TH2 balance towards TH2
108
Describe innate immunity
Present since birth, no requirement for memory
109
How are bacterial and fungal infections handled?
Phagocytosis and killing
110
How are viral infections handled?
Cellular shut down, self-sacrifice, cellular resistance
111
What is a problem with adaptive immunological memory?
Cross-reactivity or self-targeting specificity
112
What is the function of pattern recognition receptors (PPR)?
Self-non-self discrimination by recognition of unchanging patterns of microbes
113
What are 2 PRRs?
Toll-like receptors, Drosophila toll
114
Which antimicrobial peptides are secreted from lining fluids?
Defensins and cathelicidin
115
How do defensins/ cathelicidin work?
Interrupt function and transport through ion channels
116
What are lectins and collectins?
Carbohydrate-containing proteins that bind carbs or lipids in microbe walls
117
How do lectins and collectins work?
Activate complement and improve phagocytosis
118
How do pentraxins work?
React with C protein of pneumococci, activate complement and promote phagocytosis
119
What are cell associated PRRs?
Receptors that are present on cell membrane or in cytosol of cells
120
What is the main family of cell associated PRR?
TLRs
121
Where are nod-like receptors (NLR) found?
Within cytoplasm
122
What is the function of NOD2?
Recognises muramyl dipeptide and activates inflammatory signalling pathways
123
What happens in non-functioning mutations of NOD2?
Crohn's disease
124
What happens in hyper-functioning mutations of NOD2?
Blau syndrome
125
What us the function of Rig-like receptors (RLR)?
1. Detect IC double-stranded viral RNA and DNA
| 2. Couple effectively to activation of interferon production, enabling an antiviral response
126
What activates immunity to initiate tissue repair?
TLR signalling by cellular damage products
127
What increases the likelihood of successful T cell activation?
Activation of TLRs and other PPRs which drives cytokine production by antigen-presenting cells
128
How are PRRs involved in disease?
1. Recognition of host molecules
| 2. Failure to recognises pathogens or increased inflammatory responses
129
Give 3 examples of diseases PRRs are involved in
Autoimmune disease, atherosclerosis, arthritis, COPD, IBD
130
How can PRRs be used in therapies?
1. Enhance TLR signalling
2. Inhibit TLR signalling
3. Modify adaptive immune response
131
What are the clinical indications in allergic reactions in skin?
Eczema, itching, redness
132
What are the clinical indications in airway allergies?
Excessive mucus production, bronchoconstriction
133
What are the clinical indications in GI allergies?
Abdominal bloating, vomiting, diarrhoea
134
What are the clinical indications of anaphylaxis?
Airway, breathing, circulation problems
135
What is an allergy?
Abnormal response to harmless foreign material (allergens)
136
What is atopy?
Inherited tendency to exaggerated IgE response to antigen
137
What are the classes of hypersensitivity?
Immediate, acute, delayed
138
What cells are involved in the immune system?
Neutrophils and monocytes, lymphocytes
139
What are the humoral components of the immune system?
Immunoglobulins, complement, surfactant proteins
140
What is a Type 1 allergic reaction?
Immunological memory to something causing an allergic response
141
Give 3 examples of type 1 allergic reactions
Acute anaphylaxis, asthma, hayfever
142
How is atopy diagnosed?
Skin prick tests, RAST/ImmunoCAP
143
What is the treatment for hayfever?
1. Prevent exposure
2. Antihistamines
3. Reduction in local inflammation (steroids)
4. Desensitisation
144
What is the treatment of anaphylaxis?
1. Avoid/cease exposure
2. Antihistamines
3. Acute resuscitation (Adr, fluids, bronchodilators)
4. Decrease ongoing inflammation (steroids)
145
What causes type 2 reactions?
Immunoglobulins bound to surface antigens
146
What causes Goodpasture's?
Autoantibodies to a3(IV) chain of type 4 collagen
147
What are the symptoms of Goodpasture's?
Pulmonary haemorrhage and glomerulonephritis
148
What is the treatment for Goodpasture's?
Remove antibodies with steroids
149
Give 2 examples of type 3 reactions (immune complex disease)
1. Chronic bacterial endocarditis
| 2. Extrinsic allergic alveolitis
150
What happens when farmers inhale mouldy hay?
They have an acute reaction with antibody-mediated activation of the immune system
151
What are the symptoms of Type 3 reactions?
Fever, cough, flu-like illness
152
What is the management for type 3 reactions?
1. Make diagnosis
2. Avoid cause
3. Treat progressive disease with steroids
153
What happens in type 4 reactions?
Granuloma of T cells and macrophages forms
154
What disease is commonly associated with type 4 reactions?
Tuberculosis
155
What are the symptoms of drug reactions?
Breathlessness, cough, fever, chest pain
156
What tests can be done to test for drug reactions?
Lung function, CXR, CT
157
What is involved in host defence against parasites?
Basophils and eosinophils
158
What do basophils and eosinophils express?
High affinity IgE receptor
159
What are the main effector cells in IgE mediated immunity?
Mast cells
160
What is the main mast cell mediator?
Histamine
161
What do mast cell chemotactic factors typically lead to?
Eosinophil attraction and activation
162
What do mast cell derived cytokines promote?
TH2 response and can lead to B cell class switching - IgE production
163
What does local mast cell activation by cross-linkage of IgE lead to?
Recruitment of eosinophils, macrophages and neutrophils
164
What other cells types are involved in allergy?
Lymphocytes, dendritic cells, neurons, other non-immune cells
165
What determines the nature of adaptive immune response?
T cell polarisation as a result of the threat detected
166
What are the slow effects of anaphylaxis?
Pain, vomiting
167
What is the long term treatment for asthma?
Immune suppression with inhaled corticosteroids
168
What are the early and late responses of bronchoconstriction due to?
Early - IgE/mast cells
| Late - T cell response
169
What is passive immunisation?
Transfer of preformed antibodies to circulation
170
What is natural passive immunisation?
Transfer of maternal antibodies across placenta to developing foetus/breast milk
171
What is artificial passive immunity?
Treatment with pooled normal human IgG or immunoserum against pathogens or toxins
172
When might artificial passive immunisation be given?
1. Pt. with agammaglobulinaemias
2. Exposure to disease that could cause complications
3. If no time for active immunisation to give protection
173
What are the disadvantages of passive immunisation?
1. Doesn't activate immunological memory
2. No long-term prognosis
3. Possibility of reaction to antisera
174
What drugs types work by passive immunisation?
Anti-toxins and antivenins
175
What is the key feature of active immunisation?
Production of high affinity antibodies against immunogen
176
What is the goal of active immunisation?
To achieve initial exposure without risks of an infection
177
What 5 types of vaccine are there?
1. Whole organism
2. Subunit
3. Peptides
4. DNA vaccines
5. Recombinant vector vaccine
178
What are the types of whole organism vaccine?
1. Live attenuated pathogen
| 2. Killed, inactivated pathogen
179
What are the types of subunit vaccine?
1. Toxoids
2. Antigenic extracts
3. Recombinant proteins
180
What are the stages of active immunisation?
1. Engage innate immune system
2. Elicit danger signals that activate immune system
3. Engage TLR receptors
4. Activate specialist antigen presenting cells
5. Engage adaptive immune system
6. Generate memory T and B cells
7. Activate T cell help
181
What are the goals of the perfect vaccine?
1. Achieves long term protection from a small no. of vaccines
2. Stimulates B cells and T cells
3. Induces memory B cells and T cells
4. Stimulates high affinity IgG production
5. Memory B cell response depends on nature of pathogen
182
What are the advantages of live attenuated vaccines?
1. Activates all phases of immune system
2. Stimulates antibodies against multiple epitopes
3. Cheap and fast immunity
4. Attenuated pathogens set up transient infection
5. Prolonged contact with immune system
6. Fewer boosters required
183
What are the disadvantages of live attenuated vaccines?
1. If mutation of virus fails it will revert to its virulent form
2. Can't give to immunosuppressed or in tropical areas
3. Must be refrigerated for stable storage
184
What are the advantages of whole killed vaccines?
1. No risk of infection
| 2. Storage less critical
185
What are the disadvantages of whole killed vaccines?
1. Just activate humoral response
2. Lack of T cell involvement
3. Response can be quite weak
4. Usually needs 2 boosters
186
What are the advantages of recombinant protein vaccines?
1. Safer than handling live/inactivated pathogens
2. No risk of infection
3. Easier to store and preserve
187
What are the disadvantages of recombinant protein vaccines?
1. Requires boosters and adjuvants
| 2. Response less powerful
188
What are the advantages of DNA vaccines?
1. No live organism involved
2. Cheap and easily manufactured
3. Stable and resists extremes
4. Don't require complex storage
5. Delivery is simple and acceptable to widespread programmes
189
What are the disadvantages of DNA vaccines?
1. Can lead to poor immunogenicity
2. Immunological tolerance
3. Can become host genome
4. No transient infection
5. Can cause mild immune response
6. Requires boosters
190
What is the aim of DNA vaccines?
To transiently express genes from pathogens in host cells
191
How do recombinant vector vaccines work?
Imitate transient infection with pathogen using a non-pathogenic organism
192
What are the advantages of recombinant vector vaccines?
1. Produce immunological memory
| 2. Safe
193
What are the disadvantages of recombinant vector vaccines?
1. Requires refrigeration
| 2. Immune response to virus can negate effectiveness
194
What are the advantages of passive inactivated vaccines?
1. Sufficient humeral immunity if boosts given
2. Good for immunocompromised and in tropical areas
3. No mutations of virus
4. Gives immediate protection
195
What are the disadvantages of passive inactivated vaccines?
1. Potential failure of inactivation process
2. Transfer of pathogens between animals
3. Expensive
4. Little local immunity
5. Some do not increase immunity
6. Short lived so boosters required
7. Antibody mediated
