Immunology Flashcards
1
Q
Most abundant WBC
A
neutrophils
2
Q
Myeloid cells include…
A
Granulocytes, monocytes, macrophages, and dendritic cells (DCs) represent a subgroup of leukocytes, collectively called myeloid cells.
all blood cells other than lymphocytes are myeloid in origin
3
Q
Where do lymphocytes come from
(origin)
A
Lymphocytes are lymphoid in origin.
4
Q
What ois the immune system
A
body’s ability to resist or eliminate potentially harmful foreign materials (pathogens)
5
Q
Immunity
A
Protection from infectious diseases (by immune system)
6
Q
Pathogen
A
any microorganism that causes harm
7
Q
2 branches of the immune system
A
Innate immunity
Aquired (adaptive) immunity
8
Q
What gets in the way before a pathogen can invade a host and cuse infection
A
Must first attach to and penetrate the surfuce epithelial layers of the body - or other external barriers
9
Q
Give examples of externeal barriers
A
Sweat (NaCl/lysozyme), stomach (digestive enzymes/gastric acid), tears/saliva
10
Q
Summarise/define innate immunity
A
Always present (ready to attack) however many pathogenic microbes have evolved to resist innate immunity
11
Q
Summarise/define adaptive immunity
A
Stimulated by exposure to microbe (more potent)
12
Q
Give the key characteristics of the innate immune response
e.g. specificity, speed, memory, effect…
A
- Non-specific
- Can distuingish between human cells and pathogens but not between individual pathogens
- Fast and immediate (first to come into play)
- no memory: will produce the same response
13
Q
Give the key characteristics of the adaptive immune response
e.g. specificity, speed, memory, effect…
A
- highly specific
- Distinguishes between pathogens (surface antigens)
- Slower: can take days to develop
- Immunological memory: remembers
14
Q
How can we sub-divide the innate immune system
A
- Cellular: phagocytes - Eosinophils, mast cells - basophils
- Humoral: complement - cytokines
15
Q
Types of phagocyte
A
monocytes, macrophages, neutrophils, tissue dendritic cells, and mast cells
16
Q
What do phagocytes do?
function?
A
Cells of the innate immune system that track down, engulf and destroy bacteria/other pathogens as well as damaged or dead cells.
17
Q
What do phagocytes contain which allows them to work effectively
A
lysosomes that are filled with destructive enzyme and chemical to destroy the engulfed pathogens.
18
Q
Describe neutrophils
A
Most abundant WBC which tracks down, engulfs and destroys pathogens.
Contains grnaules that are filled with many destructive enzymes that kill and destroy bacteria and other pathogens
19
Q
What are macrophages a type of
A
Monocyte (WBC)
20
Q
Explain/summarises macrophages
A
Break down pathogens, process antigens and present the processed antigens to the cells of adaptive immunity to produce a specific immune response in the form of Ab and cytotoxic T cells
21
Q
What do we call macrophages
A
Antigen Presenting Cells (APC)
22
Q
Give the stages of phagocytosis
A
- Movement of phagocyte towards microbe
- Attachment of microbes the phagocyte surface
- Endocytosis of microbe and formation of phagosome
- Fusion of phagosome with lysosome
- Killing of microbe through digestion by enzymes
- Discharge (release) of waste material
23
Q
What does the lysozyme do
A
digest bacterial cell wall and has other antimicrobial proteins
24
Q
How do phagocytes produce their immune response (how do they reach the damamged tissue)
A
Constantly circulating in bloodstream so can reach any tissue
25
2 WBC which act as phagocytes
Macrophages and neutrophils
26
Eosinophil
* Combats parasitic infections
* Involved in allergy and asthma
* Granules contain many enzymes
27
What are mast cells involved in, and responsible for
Allergy
28
Give steps of an allergic response
1. Immunoglobulin E (IgE) receptor on surfact of mast cell
2. IgE antibody bind
3. 2 bit end of antibody binds to allergen which activates mast cells
4. Mast cell produces histamine (can be considered like a neurotransmitter) which produces different responses in body (as those tissues are able to express a specific receptor which will trigger a tissue-specific response)
29
What do allergen responses include
Responses include: iitchy skin, water eyes, runny nose, contraction of respiratory ways, dilated blood vessels, gastric acid secretion (stomach)
30
Basophil
* Contain** large cytoplasmic granules** with inflammatory **mediators**
* **No proven function**
* Found in blood/nearby in parasitic infection
31
What are cytokines, how are they made and what is their function
* Small proteins secreted bu immue and some nonimmue cells in respose to stimulus
* Communicate with other cells
* Bind to specific recepots on these cells producing signalling molecules that lead to many specific biological effects in these cells
* Are key players in innate and aquired immunity
32
What processes can cytokines be involved in
* Differentiation
* Activation
* Chemotaxis
* Enhancing cytotoxicity (promotes ability of some cells to kill others)
33
Cooperation within immune system
Cytokines help NKC and phagoctyes communicate
| Not sure if need to knwo more???
34
How do phagocytes and natural killer cells work
together :)
35
humoral immunity
antibody-mediated immunity. Involves helper T cell and B cells, b lymphocytes mostly involved in production of antibodies
36
Cellular Immunity
involves phagocytes, cytotoxic T cells, cytokines and chemokines, T lymphocytes mostly involved in cellular response
37
development of lymphocytes: production
| Step 1 of 3: include location
production or synthesis of T/B lymphocytes which usually takes place in the bone marrow
38
development of lymphocytes: maturation (training)
| Step 2 of 3: include location
Acquirement of specific features or structures that enable them to recognise and interact with the pathogens.
TCRs (T cell receptors)
BCRs. (B cell receptors)
Each clone /type of T or B cell can recognise and interact with different and specific pathogen /antigen.
T cell maturation in thymus, B cell maturation in bone marrow
39
development of lymphocytes: activation
| Step 3 of 3: include location
Reaction of lymphocytes with the pathogens to induce an immune response that is specific to that pathogen, in secondary lymphoid organs
40
3 steps in development of lymphocytes
* Production
* Maturation (training)
* Activation
41
Lymphatic System
| Compontents - Brief
* network of vessels called **lymphatic vessels** that carry a clear fluid called lymph
* many **lymphoid organs/ tissue** through which the lymph travels: primary and secondary lymphatic organs
42
Function of lymphatic system
* Drainage of tissue
* Absorption and transport of FA and fats
* Immunity
43
Primary lymphoid organs
Places where blood cells are produced and receive their 'early training' (acquire ability to interact with antigens) e.g. bone marrow, thymus
44
Name for formation of blood cells in bone marrow + what happens (cell types produced...)?
Hematopoiesis:
* T cells and B cells produced
* Maturation (training) of B cells
45
Thymus
made up of cortex (mainly contains mature T lymphocytes) and inner medulla (contain Macrophages, and numerous immature T lymphocytes), where maturation of T cells occurs
46
Secondary Lymphoid organs
| what happens here and what does it include
Sites of Lymphocyte activation by antigens, site of the development of adaptive immune response to antigens by T and B cells
Includes: lymph nodes, spleen, tonsil
47
Lymph nodes
| don't have to remember all of this
* Encapsulated, secondary lymphatic organs
* 500 lymph nodes
* situated throughout the body
* have access to antigens encountered in most tissues
* main function is inducing adaptive immune responses to antigens carried from the tissues by lymph
48
Spleen (+what is it made up of)
| don't have to remember all of this
150g organ located in the left upper quadrant of the abdomen, made up of red pulp and white pulp
49
Spleen - red pulp
blood filter: removing aging, damaged blood cells, particles: microorganism, opsonized microbes.
50
Spleen - white pulp
mainly contains lymphocytes, initiate immune responses to blood-borne antigens
51
Summary of 3 phases of defence of immune system
1. Recognition of danger
2. Production of specific weapons (antibodies and Cytotoxic T cells)
3. Transport of weapons to site of attack
52
What do professional antigen presenting cells include
NKC and macrophages
53
What are T Cells responsible for
Cell mediated immunity and assisting B cells
54
CD8+ cytotoxic T cells
T lymphocytes with CD8+ receptors
(Cell surface receptor is the T Cell Receptor (TCR)
which only recognises antigens when bound to **MHC I**)
55
Function of CD8+ cytotoxic T cells
Killing
56
CD4+ helper T cells
T lymphocytes with CD4+ receptors
(Cell surface receptor is the T Cell Receptor (TCR)
which only recognises antigens when bound to **MHC II**)
57
Function of CD4+ helper T cells
Stimulate B Cells to produce antibodies
58
How do cytotoxic T cells work
| (process with 3 steps)
1. binds to infected cell
2. perforin makes holes in infected cell's membrane and enzyme that can promote apoptosis enters (granzymes)
3. infected cell is destroyed
59
What are cytotoxic T cells only able to recognise
those cells expressed with the major histocompatibility complex 1 (**MHC 1**) and the antigen presented
60
What do T helper cells do (what can't they do)?
* Cant't kill infected cells/pathoges
* Can **activate and direct other immune cells** (e.g. B cells)
61
Which cells of the immune system does each effector T cells target
* Th1 activate macrophages
* Th2 activate eosinophils, mast cells - allergy
* Th17 activate neutrophil particularly in their phagocytic activity
* Tfh have a key role in helping B cell in the production of antibodies
62
How can t cells allow for different actions (of the immune response) to be mediated
There are 4 different classes of T helper, targeting 4 different classes of cells of the immune system.
63
what is the purpose of MHC class 1
| List a few features etc.
* groups of proteins (**complex**)found on the surface of virtually all nucleated cells
* main function= bind to specific components of pathogen (peptides/antigens) and present **virally induced** peptides to CD8+ to trigger **cytotoxic response**
* MHC I present antigens that are obtained from pathogens inside cells and present them only to CD8+
64
what is the purpose of MHC class 2
| List a few features etc.
* groups of proteins that are found only on the surface of **antibody presenting cells** (APC) e.g. macrophages
* bind to specific components of pathogen and present **exogenously produced antigens** to CD4+ to trigger immune response
65
What can macrophages express both forms of?
| (related to T cells)
Both MHC 1 and MHC 2
66
What is the main function of MHC
to ensure that immune response is induced only against pathogens antigen and not the self antigens or self cells and tissues, unique and key feature of the Immune system
67
What type of immunity are B cells involved in
Humoral (adaptive) immunity
68
Where are B cells produced and matured
Bone marrow
69
What do B cells express
B Cell Receptor (BCR) - antibodies
70
what is the main function of B cells?
to produce antibodies, antibodies directed against antigens
71
What happens to B cells upon activation
They are differentiated into Plasma cells (responsible for Abs production), with the help of T helper cells
72
2 outcomes for B cells
* Make antibodies to kill target cells/pathogens
* Memory B cells
73
What is the function of memory B cells
memorise the characteristics of the antigen which activated the parent B cell (during initial infection). If the memory B cell later encounters the same antigen, it triggers an **accelerated and robust secondary immune response**
74
Antigen
**Substance (usually protein) capable of triggering an immune response** due to recognition by the immune system.
Can be virus/bacterium/fungus/parasite/portion or product of one of these organisms (e.g. cell wall of bacteria, surface proteins of virus, toxic products secreted from bacteria - endoxins)
75
Antibody
Proteins that are produced as an **immune response against antigens**
Different antigens induce the **production of different antibodies**
76
2 regions of antibodies
* upper region: **antigen binding region** - the specific part of the antibody that recognises and interacts with antigen
* lower region: **Fc region** and also a B-Cell receptor
77
What are the 5 different classes of antibodies (immunoglobulins)?
1. IgM
2. IgA
3. IgG
4. IgE
5. IgD
78
Describe the function/features of IgM
First class to be produced: less specific
79
Describe the function/features of IgA
protects mucosal surfaces, resistant to stomach acid
80
Describe the function/features of IgG
main type of antibody; by binding to many kinds of pathogens such as viruses, bacteria, and fungi, protects the body from infection
81
Describe the function/features of IgE
defends against parasites, causes allergies
82
Describe the function/features of IgD
unknown function; in B cells, the function of IgD is to signal the B cells to be activated
83
3 functions of antibodies
1. Neutralization
2. Opsonization
3. Complement activation
84
Explain neutralization by antibodies
**Prevents attachment and entry**
1. Antibodies bind to the antigens on the pathogen's membrane.
2. This prevents the antigens from attaching to the host cells (receptors on plasma membrane).
3. This prevents the pathogen from invading/entering the host cell.
4. The antibodies encourage macrophages to attack the pathogen.
Mostly IgA
- Gastrointestinal tract
- Respiratory tract
85
Explain opsonization by antibodies
the coating of pathogens with antibodies in order to increase their **susceptibility to ingestion** by phagocytes - **macrophages**
86
Briefly explain complement activation by antibodies
Trigger activation of the complement pathway
87
The complement system
* consists of more than 30 proteins/factors that are found in the plasma, **present in an inactive form**
* activated in a **cascade -like format**
* activation of the complement takes place on the surface of the target cells
88
Pathways of complement system
3 pathways:
1. classical (CP) - triggered by antibodies (example of the role of the complement in the adaptive immunity)
2. alternative (AP) - effector mechanism of innate immune system
3. lectin (LP) - effector mechanism of innate immune system
* all these pathways are triggered by infection
* final result of complement activation in any of these pathways leads to the **production of membrane attack complex (MAC )**
89
What is the 3 possible results of the 3 pathways leading to the complement system
1. Enhanced phagocytosis
2. Lysis
3. Inflammation
90
Function of Membrane Attack Complexes (MAC)
makes a hole in the target cells and eventually leads to direct lysis and destruction of these targets
91
What is the function of the complement pathway
* building the MAC and **direct lysis** of target cells
* Some products increase blood flow and act as chemo-attractants and recruit other immune cells to the site of infection to **enhance the immune response**
* Other products facilitate and enhance phagocytosis (**opsonization**)
92
2 big features of adaptive immunity
* Very specific
* Immunological memory
93
How may protective immunity against a pathogen be induced
Through the host's own response to that pathogen
94
Active immunity
The transfer of antibodies or lymphocytes specific for the microbe
95
Passive immunity
induced through the transfer of antibodies or lymphocytes specific for that microbe from another individual
96
Immune/protected individuals
Individuals who have encountered a pathogen and are protected form subsequent encounters and production of antibodies
97
Susceptible/naive individuals
Individuals who have not yet encountered a particular antigen
98
Features of active immunity
* produced by host own immune system
* takes weeks to develop
* memory cells produced
* protection is permanent
99
Features of passive immunity
* transfer of antibodies/cells from other individual
* happens immediately
* no memory cells
* protection temporary
100
What are the most important features of active immunity
* Immune response is very specific
* immunological memory due to production of memory cells
* basis of vaccination or immunisation
