Immunology Flashcards
1
Q
What is immunopathology?
A
Tissue damage caused by excessive immune response
2
Q
What do most immune cells arise from?
A
Bone marrow
pluripotent haematopoietic stem cell
3
Q
what do bone marrow stem cells differentiate into?
A
Lymphoid progenitors
Myeloid progenitors
4
Q
What arise from lymphoid progenitors?
A
B cells, T cells and NK cells
5
Q
What arise from myeloid progenitors?
A
Macrophages phagocytes platelets mast cells etc.
6
Q
What is innate immunity?
A
non specific recognition
no memory
7
Q
What is adaptive immunity?
A
Specific recognition of foreign material
Generation of memory
8
Q
What cells are involved in innate immunity?
A
Phagocytes
mast cells
Natural killer cells
9
Q
What cells are phagocytes?
A
Macrophages
neutrophils
eosinophils
basophils
10
Q
What cells are involved in adaptive immunity?
A
Lymphocytes
11
Q
What cells are lymphocytes?
A
T cells
B cells
Immunoglobulins/antibodies
Antigen presenting cells
12
Q
What cells are antigen presenting cells?
A
Dendritic cells
Macrophages
B cells
13
Q
What are dendritic cells derived from?
A
Both lymphoid and myeloid progenitors
14
Q
What do dendritic cells do?
A
Activates the adaptive immune response
link the innate and adaptive immune systems
15
Q
What are humoral components?
A
Soluble factors
eg. complement system
acute phase proteins
interferons
16
Q
What do macrophages do?
A
Kill intracellular pathogens
raise alarm following infection
17
Q
WHat do neutrophils do?
A
Kill rapidly dividing bacteria
18
Q
What do eosinophils do?
A
Kill parasites
19
Q
What do natural killer cells do?
A
Kill virus infected cells
20
Q
What do interferons do?
A
Activate cells to produce antiviral proteins
21
Q
What does the complement system do?
A
Coats pathogens in antigens for recognition
22
Q
What does opsonises mean?
A
Enhances phagocytosis
23
Q
What cells only have one nucleus?
A
Monocytes
Macrophages
24
Q
What cells are polymorphonucleated?
A
Neutrophils
Basophils
Eosinophils
25
How do phagocytes activate the innate immune system?
Take up antigens
are activated and Travel to lymph nodes
Activate naive T cells
26
What is phagocytosis?
Take in bacterua
| granules fuse and digest bacteria
27
What are epitopes?
The part of the antigen that the immune system is targeting
28
What is a hapten?
Joins with a carrier protein molecule to form an epitope which the immune system can bind to
29
What is an immunogen?
A substance which induces an immune response when injected into an individual
30
What is an adjuvant?
A substance which enhances the immune response when combined with antigen
31
What are examples of adjuvants?
Oil and water
peanut oil
Liposomes
Cytokines
32
What are the different regions of an immunoglobulin?
Constant domain
variable domain
hypervariable domain
33
Which immunoglobulin has 5 y shaped units?
IgM
34
What is the main Ig in secondary immune response?
IgG
35
What is IgA used for?
Mucosal immune defence in gut
36
What is IgE involved in?
Allergies
37
Where is IgD found?
On immature B lymphocytes
38
What is the word for multiple Ig binding sites?
Avidity
39
Where are the primary sites of immune system development?
Bone marrow
Thymus
Ileal peyers patch
Bursa of Fabricus
40
Where are the secondary sites of immune system development?
Lymph nodes
| spleen
41
What occurs in the bone marrow?
Origin of T and B lymphocytes
| Site of B cell maturation
42
What is the ileal peyers patch
The site of B cell maturation in most animal species
43
Where is the ileal peyers patch/
In the small intestine
44
What is the site of B cell maturation in birds?
Bursa of fabricus
45
Where is the bursa of fabricus located?
near the cloaca
46
What occurs at the thymus
T cell development
47
What produce growth factors in teh thymus?
Hassalls corpuscle
48
Where are the B cells located in the lymph nodes?
In the follicles in the cortex
49
Where are the T cells located in the lymph nodes?
In the paracortex
50
What are the different areas of the lymph node follicles?
Germinal centre
| mantle zone
51
Where are the lymphocytes located in the spleen>
In the white pulp
52
What are the uncapsulated lymphoid tissue?
mucosa associated lymphoid tissues
| mucosal surfaces which are in contact with the outside environment
53
What is an activated lymphocyte called?
Lymphoblast
54
What do T cells express?
T cell receptors
55
What do B cells express?
Surface membrane immunoglobulins
56
What does homing mean?
Lymphocytes move to sites of infection
| different mucosal system areas attract same lymphocytes
57
What are T killer cells called?
CD8+ T cells
58
What do CD8 T cells do?
Kill infected cells
59
What are T helper cells called?
CD4+ T cells
60
What do CD4 T regulatory cells do?
Inhibit immune responses so it doesnt damage healthy tissue
61
What do CD4 TH1 cells do?
Activate macrophages
| target bacteria
62
What do CD4 TH2 cells do?
Switch B cell production to IgE
| Target parasites
63
WWhat do CD4 TH17 cells do?
enhance neutrophil response
| Target fungi
64
What do T cells recognise?
T cell receptors recognise small peptide fragments bound to the major histocompatibility complex at the cell surface
65
What type of T cells see epitodes presented by class 1 MHC?
CD8+ T cells
66
What cells are MHC class 1 found on?
Nucleated cells
67
What type of antigens do MHC class 1 molecules present?
Endogenous/cytosolic antigens
| usually viral proteins from inside the cell
68
What cells see epitodes presented by class 2 MHC?
CD 4+ helper cells
69
What are MHC class 2 found on?
Antigen presenting cells
70
What type of antigens do MHC class 2 molecules present?
Exogenous antigens
71
Peptide fragments are longer in which MHC?
MHC class 2
72
What are exogenous antigens degraded in?
ENdocytic vesicles using a low pH
73
What present lipid antigens?
CD1
74
What induces cells to express MHC class 2?
Interferon gamma cytokine
75
How do dendritic cells target pathogens?
Phagocytosis - ingest antigens
Macropinocytosis - engulf non specific fluid
use pattern recognition receptors to recognise pathogen
76
What are immature conventional dendritic cells called?
Langerhans cells
77
What are PRRs?
receptors on dendritic cells whcih recognise PAMPS
78
WHat are PAMPS?
Pattern associated molecular patterns
| they are nucleic acid motifs
79
WHat are cytokines?
soluble factors wich bind to specific receptors on cells to alter their function
80
What are chemokines?
Chemotactic recruitment of cells from blood into the tissue
81
What is the main enzyme produced in the complement cascade?
C3 convertase
82
What triggers the complement cascade?
Pattern recognition trigger
| the complex between the antibody and the antigen
83
What happens after the complement cascade is triggered?
C1 units attach to the antibody - q then r then s
84
What does C 1 act on?
C4 and C2
85
What occurs after C4 and C2 are activated?
They split into two fragments - a and b
86
What creates C3 convertase?
The halves of C2 and C4 joining together - C2a and C4b
87
What action does C3 do?
Attaches to the surface of the antigen
| Splits C3 into 2
88
What is C5 convertase made up of?
C3 convertase (C2a and C4b) and C3b
89
What are the consequences of complement system activation?
Inflammation
Opsonisation - helps bind to phagocytic cells
Immune complexes adherence to erythrocytes for clearance
Cytolysis - killing cells
90
What does C5 do?
Creates the membrane attack complex
91
What does the MAC do?
Creates holes in the membrane
| causes osmotic lysis
92
How is the complement cascade controlled?
C1 inhibitor
membrane proteins to breakdown C3 convertase
CD59
93
What does CD59 do?
Prevent formation of MAC on normal cells
94
What are MHC genes?
Genes that code for major histocompatibility complexes
95
What make MHC good at targeting pathogens?
Polymorphic - different alleles specific to an individual
Polygenic - individuals have several different ones
Able to present multiple different peptides
96
How are MHCs inherited?
two sets of MHC alleles from mother and father
| codominant expression - all are expressed
97
What is the cause of graft rejection?
Alloreactivity - immune system reacts to never seen before allogeneic MHC
98
What are other problems with MHC?
Affect disease susceptibility
| Cause resistance and production traits
99
What does recognition of the peptide-MHC complexes require?
Two receptors on the T cells:
T cell receptor
Co receptor CD4 or CD8
100
What does the CD4/8 coreceptor bind to?
Lck signalling molecule which activates the T cell
101
What may be a cause of autoimmunity?
T cell crossreactivity
102
What is T cell crossreactivity?
Where one TCR can recognise lots of MHC
103
What is somatic recombination?
Where genes are rearranged to generate TCR diversity
104
What is immune deviation?
Where immune responses are polarised towards Th1 or Th2
| they are mutually antigonistic
105
What is Th1 cell immunity?
Produce interferon gamma
inhibits Th2 cells
causes CD8 cytotoxic T cell mediated immunity
106
What is Th2 cell immunity?
Produce IL-4 and IL-13
| causes humoral immunity - primarily antibodies
107
What do CD8 cytotoxic T cells target?
They kill target cells which have specific MHC1
108
How do CD8 T cells kill their target cells?
Perforin - pores
Granzymes - apoptosis
close adhesion to target cells
109
What are the mechanisms of cytolysis?
Tight junctions are formed
Cytotoxic granules are polarised to the site of tight junctions
Fas and fas ligand interact to activate apoptosis
110
What activates natural killer cells?
Interferon alpha
111
What do natural killer cells do?
Release lytic granules of perforin and granzymes which kill virus infected cells
112
What activates natural killer cells?
when the target cell has altered/down regulated MHC1
| MHC1 inhibits NK cells
113
What is antibody dependent cellular cytotoxicity?
Fc receptors on NK cells bind to antibodies attached to the target cell
this kills target cell
114
Where are gamma delta T cells found?
Mucocutaneous surfaces - innate immune system
115
How does T cell therapy work?
Isolate T cells
modify to express different receptors
use vectors to encode DNA
They activate and kill target cells better eg. cancer
116
How do B cells identify antigens?
T cell dependent
Large conformational determinants or epitopes bind
Co stimulation
Cytokine production
117
what antibodies do virgin B cells express?
IgM and IgD
118
What happens when a B cell is activated?
Becomes a lymphoblast
Ig change to IgG, IgA or IgE
Express more MHC2
proliferate and differentiate
119
What is the summary of antibody production?
Antigen presenting cell picks up an antigen
It presents the antigen to the T helper cell via MHC2
This stimulates a T helper cell response
The B cell has engaged with the antigen but needs the T helper cell to fully activate
This causes the B cell to activate and differentiate into a plasma cell
The plasma cell can then pump out the antibody needed for immunity
120
Where are B cells activated?
Germinal centres of secondary lymphoid tissue
121
What area of the antibody determines what type it is?
The heavy chain contast region
| genes
122
How is the change of antibodies achieved in B cells?
Gene rearrangement
| then theyre transcribed, RNA spliced, translated and expressed
123
How is B cell receptor diversity achieved?
Somatic mutation and gene conversion
124
What is affinity maturation?
When B cells with high affinity receptors for the epitopes are selected as immune response matures and antigen conc decreases
125
What are monoclonal antibodies?
A single species of high affinity antibody for one specific epitope
126
What are monoclonal antibodies used for?
Allergy diagnosis
cancer treatment
block viral infection
treat autoimmunity
127
How are monoclonal antibodies made?
```
Immunise mouse
activates many B cells
remove spleen
nuclear material added to make immortal B cells
dilute
expand
harvest
```
128
What are mechanisms of immunosuppression?
Antigens used up
Antibody mediated suppression
Immune complexes release PGE2
Bound antibodies inhibit each other
129
What hormone causes immunosupression?
Cortisol - stress
| also balance of hormones eg pregnancy
130
WHat are supressor T cells?
CD4+
| regulate the balance of Th1 v Th2
131
What cytokine is produced by Tr1 cells which is an induced supressor?
IL-10
132
What is a natural immune supressor?
CD4+ CD25+ T reg
133
What is hypersensitivity?
Sensitisation to a specific antigen by repeated exposure causes an excessive immune response
134
What is a type one hypersensitivity?
Immediate
135
What is a type two hypersensitivity?
Antibody dependent
136
What is a type 3 hypersensitivity?
Immune complex
137
What is a type 4 hypersensitivity?
Cell mediated or delayed type hypersensitivity
138
What is type 1 hypersensitivity caused by?
Allergens cause development of allergen specific IgE
139
What is IgE usually found bound to?
FcERI in mast cells and basophils
140
What are the two stages of type one hypersensitivity?
1. sensitisation
| 2. hypersensitivity
141
What occurs in stage 2 of type one hypersensitivity?
Allergen cross links IgE
| this causes mast cell degranulation and an inflammatory reaction
142
What is a systemic type 1 hypersensitivity called?
Anaphylaxis
143
What is the hygiene hypothesis in relation to type 1 hypersensitivity reactions?
Repeated infection as a child induces bystander suppression - increase in T regulatory cells
144
What is type 2 hypersensitivity triggered by?
Production of antibody that can bind to a target cell and cause opsonisation, lysis and antibody dependent cytotoxicity
145
What are two examples of type 2 hypersensitivity?
Blood transfusion reactions
| antibody mediated autoimmune diseases - eg destroying own RBCs
146
What is sometimes called type 5 hypersensitivity?
Anti receptor antibodies
147
What happens in a type 5 hypersensitivity reaction?
Immune system targets receptor
| antibodies bind to the receptor and accidentally have a stimulatory or inhibitory effect
148
What is an example of type 5 hypersensitivity?
Graves disease
| mimics thyroid stimulating hormone so excess thyroid hormone produced
149
What are the two different types of type 3 hypersensitivity?
Antigen excess
| Antibody excess
150
What occurs during antibody excess in type 3 hypersensitivity?
Sensitisation causes excessive IgG response
| local exposure to allergen causes local inflammatory response
151
Where is type 3 hypersensitivity most common?
In the respiratory tract
152
What occurs during antigen excess in type 3 hypersensitivity?
Sensitisation leads to circulating antibody
| exposure to antigen causes small soluble immune complexes in the blood
153
What are the consequences of type 3 hypersensitivity antigen excess?
Vasculitis
Complement activation
Inflammation
154
WHere does antigen excess occur?
Areas of high turbulence and high blood pressure
| eg. renal glomeruli
155
What cells are involved in type 4 hypersensitivity?
Mononuclear cells and cytokine
156
What triggers type 4 hypersensitivity?
Contact allergy
157
What is different about type 4 hypersensitivity?
Delayed in onset 24 to 72 hrs
158
What is immune tolerance?
Failure of the immune systme to respond to an antigen
159
What is neonatal tolerance?
Where shared placental circulation develops tolerance to alloantigens
160
WHat is oral tolerance?
Failure to respond systemically to antigen previously given orally
supresses immune responses
161
What is self tolerance?
immune system doesnt recognise self antigens
162
What is autoimmunity?
Failure of self tolerance
| activation of autoreactive cells
163
What are triggers of autoimmunity?
Genetics
age
gender - females predisposed
environmental triggers
164
What is molecular mimicry?
Where the pathogenic antigen might actival T cells which are also autoreactive
165
How does the embryonic immune system develop?
```
Thymus develops - t cells
spleen and bone marrow develop - b cells
first trimester - lymphocytes can respond
complement develops
can make blood antibodies by day 100
```
166
What type of placentation is in dogs and cats?
Endotheliochorial placentation
| small amount of IgG passes
167
What type of placentation is in ruminants?
Syndesmochorial placentation
| No Ig transfer
168
What barriers are present in syndesmochorial placentation
Uterine connective tissue
Maternal endothelium
Chorionic epithelium
169
What type of placentation is in horses and pigs>
Epitheliochorial placentation
| No Ig transfer possible
170
What barriers are in epitheliochorial placentation?
```
4 layers
Uterine epithelium
Uterine connective tissue
Maternal endothelium
Chorionic epithelium
```
171
What is the main Ig in ruminant milk?
IgG
172
WHat is the main Ig in non ruminant milk?
IgA
173
How is neonatal vaccination done?
Various times so colostral antibodies dont interfere
174
What is neonatal isoerythrolysis?
When colostrum contains antibodies against neonates own erythrocytes
causes anaemia
175
What causes neonatal isoerythrolysis?
Dam sensitised to the sire erythrocytes antigens
176
Why do cats get neonatal isoerythrolysis?
Type B cats have anti A
| type A/AB kittens from a type B queen develop it
