Intro to immune system Flashcards
(83 cards)
1
Q
What is the immune system?
A
- a defensive system evolved over millions of year of constant battle with fast evolving pathogens
2
Q
What are the characteristics of the immune system?
A
- diverse and complex
- overlapping/ partially redundant system
3
Q
Why is there so much evolution involved in the immune system?
A
- To make sure there isn’t a single point of weakness in the system
4
Q
What are the components to the animals immune system?
A
- many tissues
- cells
- molecules
5
Q
What are the critical aspects of the immune system?
A
- Barrier
- Identify
- Kill
- Remember
6
Q
The immune system can be divided into what two arms?
A
- Innate immune system
- Adaptive immune system
7
Q
What is the innate immune system present in?
A
- present in all plants, invertebrates and vertebrates
8
Q
What type of recognition does the innate immune system have?
A
- non-specific recognition with no specific memory response
9
Q
What is the adaptive immune system present in?
A
- vertebrates only
- and is not the same in every vertebrate
10
Q
What recognition does the adaptive immune system have?
A
- specific recognition with an ability for specific memory responses
11
Q
How are receptors in the innate and adaptive immune cells different?
A
- Fundamentally different in the way they are generated
12
Q
What does different generation of receptors in immune cells lead to?
A
- leads to differences in specificity
13
Q
Describe innate recognition:
A
- broad groups of pathogens
- e.g., gram positive and negative but not the specific bacteria
14
Q
Describe adaptive recognition:
A
- can work at strain level and be very specific in identification
15
Q
How does the innate immune system know when and what to attack?
A
- Has to recognise either a breach in barrier or what pathogen has breached the barrier
16
Q
How does the innate immune system identify pathogens?
A
- through self/non-self molecules
- recognise things that are not part of animals body e.g., uniquely different
17
Q
What type receptor does the innate immune system have?
A
- pattern recognition receptors (PRRs)
18
Q
What are PRRs?
A
- innate cell receptors that recognise conserved non-self molecules
19
Q
Name an example of a non-self molecule:
A
- Lipopolysaccharide (only in gram negative bacteria)
20
Q
What are non-self molecules collectively known as?
A
- Pathogen-associated molecular patterns (PAMPs)
21
Q
What does PAMPs being highly conserved mean for recognition?
A
- hard for pathogens to evade recognition
22
Q
What happens during the innate immune recognition response?
A
- The PRR bind to the PAMPs
23
Q
What are the 7 major cell types involved in the innate immune cells?
A
- dendritic cells
- macrophages
- neutrophils
- eosinophils
- basophils
- mast cells
- mast cells
23
Q
What do all innate immune cells possess?
A
- PRRs
24
What means animals are more likely to suffer bacterial infections?
- issues with the toll-like receptor 4
25
What can trigger the innate immune recognition?
- By damaged associated molecules
26
What are examples of immune cell receptors?
- TLRs
- RAGE
27
What are the molecules not released in mammals?
What happens when they are found outside of the cell?
- DNA not found outside nucleus
- HMGB1 - DNA binding proteins
- these damage associated molecules are recognised
28
What is the innate immune response based on?
- based on receptors that do not change (germline inherited)
29
What can the innate immune response recognise?
- recognise conserved structures (e.g., LPS)
- non-specific, broad groups of pathogens
- also can recognise conserved damage-related molecules
30
What cells are used in the adaptive immune response?
- B lymphocytes
- T lymphocytes
31
What do B lymphocytes do in the adaptive immune response?
- secrete antibodies (immunoglobulins)
32
What are the two major T lymphocyte cell types?
- A/CD4+ T lymphocytes
- B CD8+ T lymphocytes
33
What do A/CD4 + T lymphocytes do?
- Helper T lymphocytes which help other cells
34
What do CD8+ T lymphocytes do?
- cytotoxic T lymphocytes (kills cells - important in infected host cells) and intracellular infections
35
What are B lymphocytes?
- B-cell receptor (BCR) - a surface transmembrane immunoglobulin (antibody on surface)
36
What are T lymphocytes?
- T-cell receptor (TCR) - a surface transmembrane immunoglobulin
37
What are both B lymphocytes and T lymphocytes referred to?
- antigen receptors
38
What is an antigen?
- any substance that can bind to specific lymphocyte receptors and so induce an immune response
39
What substances can be classed as antigens?
- lipids
- carbs
- proteins
- a pathogen will contain multiple antigens, don't need to be conserved
40
What are epitopes?
- most antigens have multiple specific regions that the antibody or T cell receptor binds to this is called an epitope
41
Unlike innate receptors what can adaptive TCRs and BCR do?
- they can differ between cells in the same body
42
What means the adaptive immune system can respond to anything?
- the TCRs and BCR can differ between cells in the same body
- created by random recombination of segments of receptor encoding genes early in cells
43
Describe antibody formation?
1. initially each pre-B cell has the same light chain and heavy chain genes (these encode antibody)
2. these genes have multiple options
3. this creates vast diversity so can bind to anything
44
How do the innate and adaptive immune responses work?
- innate and adaptive immune responses evolved together in vertebrates = lots of links
45
Most responses to viruses, bacteria, fungi, helminths, ectoparasites are what?
- are both innate and adaptive
46
The immune system encompasses numerous cell and tissues
what cells does it include?
- includes immune cells and non-immune cells
47
What tissues does the immune system involve?
- includes tissues evolved for immunological function = lymphoid tissues and other tissues
48
What are white blood cells called?
What percentage of the whole blood do they make up?
What is there main function?
- known as leukocytes
- < 1% of whole blood
- main function is killing invading pathogens
49
Describe red blood cells:
- 1 cell lineage = myeloid
- one major function
- few differences (related to age of cells)
50
Describe white blood cells:
- 2 cell lineages = myeloid/lymphoid
- many functions
- many differences (morphology, size, cell types)
51
What is myelopoiesis?
- process of myelocyte production
52
What is lymphopoiesis?
- process of lymphocytes production
53
How are NK cells, T and B lymphocytes made?
1. hemocytoblast stem cell in bone marrow form ...
2. lymphoid stem cells which go on to form ...
3. NK cells, T and B lymphocytes
54
Describe how neutrophils, eosinophils, basophils and monocytes are formed?
1. hemocytoblast stem cells in bone marrow form ...
2. myeloid stem cells which form ...
3. myeloblast which forms ...
4. neutrophils etc...
55
What are the different types of WBCs?
- neutrophils
- monocytes
- eosinophils
- basophil
- lymphocytes (bunched together in count)
56
What are neutrophils?
- earliest responders to any infection = front line
- largest percentage of WBCs in most species
57
What is the percentage of neutrophils in:
1. dogs
2. horses
3. cows
1 . 58-85%
2. 52-70%
3. 15-30%
* sidenote - in cows/sheep lymphocytes are higher
58
What is the lifespan of neutrophils and describe what they look like under a microscope?
- short life span (1-4 days)
- granulated (faint granules in cytoplasm)
- multilobed nucleus
59
What is the main role of neutrophils in immune response?
- phagocytosis (eating pathogens)
- anti-microbials (via degranulation)
60
What are monocytes?
what percentage of WBCs do they make up in dogs, horses and sheep?
- in the bloodstream they are called monocytes
- dogs = 2-10%
- horses and sheep = 0-6%
61
When monocytes arrive at tissue what do they develop into?
- macrophages
- dendritic cells
62
Monocytes tend to function when they get into tissues - what do they look like and what is there lifespan?
- long lived but only in bloodstream for 1-3 days
- large cells (largest leukocytes)
- agranulated (no dark granules)
- kidney-beaned shaped nuclei
63
What is the main role in monocytes in the immune response?
- phagocytosis
- antigen presentation very important in adaptive
- cytokine release
64
What are cytokines?
- small, soluble proteins (peptides and glycoproteins)
- intracellular messengers of the immune system
65
Name two cytokines:
- interleukins (IL-2)
- interferons (IFNy)
66
What do cytokines do?
- bind to specific membrane receptors leading to signal
- can have short or long pathways
67
What are chemokines?
- subset of cytokines
- specialised function = chemoattractants
68
Give two examples of chemokines?
- CXCL8
- CCL2
69
What do chemokines do?
- mobilise immune cells to move to tissues or within tissues to right place
- they produce a gradient for the cell to follow in order to reach the correct site
70
What do eosinophils look like under a microscope?
- bilobed nucleus
- more heavily granulated
71
What are the percentages in eosinophils in dogs, horses and cattle?
- dogs = 0-9%
- horses = 0-7%
- cattle = 0-20%
* may not see them in every BC
72
How long do eosinophils spend in the bloodstream and in tissues?
- approx. 30 min in bloodstream
- 12 days in tissue
73
What can a rise in eosinophils suggest?
- rise can suggest helminth/allergy response
74
What are the main roles of eosinophils in the immune response?
- release inflammatory mediators (via degranulation)
- release a-helminth molecules (via degranulation)
- do not release histamine
75
What are basophils involved in?
- involved in helminth/allergy responses
76
What are the percentages of basophils in dogs, cats, horses and cattle?
- dogs and cats = 0-1%
- horses and cattle = 0-2%
77
Where are basophils normally located?
- normally not found outside of the bloodstream
- more specialised for blood
78
What is the lifespan of basophils and what do they look like under the microscope?
- short-lived (3 days)
- granulated
- bilobed nucleus
79
What are basophil main role in the immune response?
- less well defined
- igE triggered degranulation
- release histamine and other mediators
80
Lymphocytes are a lot more common what cells do they include?
- B lymphocytes
- T lymphocytes
- NK cells
81
Lymphocytes are hard to distinguish describe why and what you can work out by looking at them?
- cant really distinguish in a basic blood smear
- can tell mature vs immature based on cytoplasm
82
What do lymphocytes look like under the microscope?
- agranulocytes (like monocytes) - so clearer cytoplasm
- small - little bigger than RBCs
- nuclei (relatively circular) - not bilobed, take up more of cell
