Immunology Flashcards
1
Q
What is self-tolerance?
A
The body’s immune defenses do not normally attack tissues that carry a self marker
2
Q
What are the physical barriers of first line of defence?
A
Skin and mucosal barriers (reproductive, respiratory, digestive tract)
3
Q
What are the two types of immune system?
A
Innate and adaptive
4
Q
What immune system produces antibodies and has a memory?
A
Adaptive
5
Q
Which type of immune system is the first to respond?
A
Innate
6
Q
Where does hematopoiesis occur in adults?
A
Sternum, vertebrae, iliac bones, ribs
7
Q
What cells are matured in the thymus?
A
T lymphocytes
8
Q
What do the common lymphoid progentior cells produce?
A
B lymphocytes, NK cells, T lymphocytes
9
Q
Where are monocytes/macrophages made?
A
Bone marrow
10
Q
What do monocytes divide and different into?
A
Macrophages
11
Q
What are some of the functions of macrophages (4)?
A
- Give off chemicals that restrict blood flow away from site of injury
- Contraction of endothelial cells
- Produce cytokines to alert other cells to the ‘danger’ and induce them to travel to the site of injury
- Phagocytotsis
12
Q
What is the most abundant white blood cell?
A
Neutrophil
13
Q
What do neutrophils do?
A
Phagocytosis
14
Q
What type of infections do eosinophils help combat?
A
Parasitic infections
15
Q
What other types of reactions are eosinophils involved in?
A
Allergy and asthma
16
Q
What do mast cells contain and what does it do?
A
Histamine which leads to bronchospasm and vasodilation
17
Q
What is the least common of the granulocytes?
A
Basophils
18
Q
What other cell - other than mast cells - store histamine in their granules?
A
Basophils
19
Q
Where are NK cells found?
A
In blood and spleen
20
Q
How do NK cells bore holes in target cells?
A
By secreting perforin
21
Q
What are non-specific humoral factors?
A
Within body fluids a variety of soluble substances with protective functions
22
Q
What are some examples of non-specific humoral factors?
A
Growth inhibitors, enzyme inhibitors, lysins, complement proteins
23
Q
What are the three activation pathways of the complement system?
A
- Classical
- Alternative
- Lectin
24
Q
What is MAC?
A
Membrane attack complex
25
What does the complement system consist of?
Serum and cell surface proteins that interact with one another and other molecules in the immune system in highly regulated manner
26
What is the same outcome for all three of the different activation pathways of the complement system?
Lysis of the target cell and/or opsonisation of pathogens
27
What pathways of the complement system are effector mechanisms of the innate immune system?
Alternative and lectin
28
What are membrane attack complexes?
Structure formed on surface of pathogenic bacterial cells as a result of activation of one of the host's complement pathways, it forms transmembrane channels and these channels disrupt the cell membrane of target cells causing cell lysis and death
29
What are some of the functions of the complement system (4)?
1. Induce lysis of microbes (MAC)
2. Promote phagocytosis of microbes (opsonisation)
3. Stimulate inflammation - activate mast cells and neutrophils
4. Also stimulate activation of B cells and Ab production
30
What are cytokines?
Chemicals used by cells to communicate with other cells
31
What is acute inflammation?
The initial response of the body to harmful stimuli
32
What happens during chronic inflammation?
Progressive shift in the type of cells which are present at site of inflammation and is characterised by simultaneous destruction and healing of tissue from inflammatory process
33
What are the functions of the lymphatic system?
Drainage of tissue, absorption and transport of fatty acids and fats, immunity
34
What is the route of lymphatic drainage?
Lymph --> afferent vessel --> lymph node --> efferent vessels (filtered lymph) --> lymphatic duct --> venous system --> blood
35
What are primary lymphoid organs?
Places where blood cells are produced and receive their 'early training' = bone marrow and thymus
36
Where are the main sites of hematopoieseis before birth?
Yolk sac, liver, spleen and bone marrow
37
What happens in the thymus?
Maturation of T cells
38
What other cells can be found in the thymus?
Macrophages, dendritic cells and thymocytes (T cell precursors)
39
What are the secondary lymphoid organs?
Sites of lymphocyte activation by antigens including: lymph nodes and lymphatic system, spleen, tonsils, cutaenous and mucosal immune systems
40
What is the function of the white pulp in the spleen?
Contains antigen presenting cells (APCs), B cells and T cells which promote the interaction requied for the efficient development of the humoral immune responses
41
What is the function of the red pulp in the spleen?
Filter blood
42
What is in the T cell zone of the white pulp of the spleen?
Central arteriole surrounded by lymphocytes called the periateriolar lymphoid sheath (PALS)
43
What are the zones of the white pulp of the spleen?
T cell zone, B cell zone and marginal zone
44
What is the red pulp of the spleen composed of?
It is a vascular sinusoid with: large no of red blood cells, macrophages, dendritic cells, lymphocytes and plasma cells
45
What is a feature of all secondary lymphoid vessles except the spleen?
High Endothelial Venules
46
What is the purpose of HEVs?
Much looser type of join between cells through which lymphocytes can escape the blood vessels at high speed
47
What are the functions of lymph nodes (4)?
1. Filter and purify lymph before venous system
2. Remove most of antigen
3. In response to APCs, T cells and B cells stimulate and adaptive immune response initiated
4. Maintain and produce B cells and house T cells
48
What are Peyer's patches?
Secondary lymphoid tissue found in the small intestine, B cell rich
49
What are M cells?
Specialised epithelial cells covering Peyer's patches which transport Ag from lumen of intestine to Peyer's patch
50
What are T cells responsible for?
Cell mediated immunity and assisting B cells
51
What is a T cell receptor (TCR)?
A cell surface receptor which only recognises antibody when bound to MHC
52
What must T cells learn during selection?
Not to recognise our own 'self' antigens and must recognise Ag in associaton with our own MHC
53
What are T cells presented with in thymus?
Present with 'self' MHC on epithelial cells, those that recognise and whose receptor binds MHC molecules will live, those that don't interact with MHC molecules will die
54
What is negative selection for self-MHC peptide?
Death of T cells with high-affinity receptors for self-MHC or self-MHC + self-antigen
55
Where are MHC Class I molecules found?
All nucleated cells
56
What is the purpose of MHC Class I molecules?
Presents 'virally induced' peptides to CD8+ T cells and trigger cytotoxic response
57
Where are MHC Class II molecules found?
Only on professional antigen presenting cells (APCs)
58
What is the purpose of MHC Class II molecules?
To present exogenously produced Ag to CD4+ T cells and acctivate macrophages and B cells
59
What do T helper cells do?
Activate and direct other immune cells as cannot kill infected cells or pathogens
60
What are T helper cells essential for?
B cell Ab class swithcing and in activation and growth of cytotoxic T cells
61
What do cytotoxic T cells do?
When exposed to infected/dysfunctional somatic cells they release perforin which forms pores in target cell, also releases Granzyme B (a protease) that can enter target cells via the perforin-formed pore and induce apoptosis
62
Where do memory T cells arise from?
Can arise from fully or partially differentiated T cells
63
What do TH1 cells do?
Are part of the cellular immune system, maximise the killing effectc of macrophages and proliferation of cytotoxic T cells
64
What do TH2 cells do?
Are part of the humoral immune system, stimulates B cells into proliferation, to induce B cell antibody class switching and to increase neutralising antibody production
65
What is the principle cell that orchestrates allergic and asthmatic inflammation?
CD4+ Th2 cell
66
What cells work togeth to creata asthma symptoms?
Mast cells and eosinophils
67
How do B cell lymphocytes recognise antigen?
Recognise free organic antigen via B-cell recepor (surface IgM)
68
How do T cell lymphocytes recognise antigen?
Need to be shown protein antigen in association with MHC
69
How are secondary immune responses different to primary immune responses?
They are more rapid, larger and often qualitatively different
70
How do memory B cells differ from naive B cells?
Memory B cells produce antibodies that bind to the antigen with a much higher affinity than naive B cells
71
How do memory T cells differ from naive T cells?
Memory T cells react much more quickly than naive T cells
72
What are the two types of immunity?
Active and passive
73
Which type of immune response generates immunological memory
Active
74
What happens during active immunity?
Given an infection to make our own antibodies and so develop memory
75
What happens during passive immunity?
Given antibodies already created in another organism, no immunological memory
76
Which type of immunity is faster: passive or active?
Passive - is immediate
77
What do B cells mature into?
Plasma cells
78
What are plasma cells responsible for?
Antibody production
79
What do B cells express?
They express surface immunoglobulin which is the antigen receptor for the B cell
80
What cells is it more important to tolerize?
T cells - because B cells can't make antibodies to most antigens without help of T cells
81
Where is the antigen binding region on an antibody?
At the light chain end
82
What are the two types of light chain?
Kappa and lamda
83
What does the heavy chain part of the antibody do?
Define the classes of Ig
84
What are the two regions of a heavy chain?
A constant region (same for all Ig of same class) and a variable region (differs between different B cells)
85
How many types of Ig are there in heavy chains and what are they?
5 - gamma (IgG), delta (IgD), alpha (IgA), mu (IgM), epsilon (IgE)
86
What is opsonization?
The process by which a pathogen is marked for ingestion and eliminated by the phagocytes
87
What is IgM good at?
Good at fixing compliment and opsonization
88
What is IgG good at?
Good opsonizer
89
What is IgA good at?
Protects mucosal surfaces/resistant to stomach acid
90
What is IgE good at?
Defends against parasites, causes anaphylactic shock and allergies
91
Which class of antibody has no known antibody function?
IgD
92
What is the only antibody that can cross the placental barrier?
IgG
93
What antibody is present in the mothers milk?
IgA
94
What do you need to have for complement activation?
An antigen-antibody complex
95
What is neutralisation?
The ability of specific antibodies to block the site(s) on viruses that they use to enter their target cell
96
What is transcytosis?
The method by which IgA is transported from the lamina propria through mucosal epithelial cells to the lumen by binding to poly-Ig receptor
97
What does mast cell degranulation cause?
Anaphylactic shock
98
What are BCR (B cell receptors) specific for?
Particular antigens
99
What are the two ways you can activate a B cell?
1. With T cell help (T cell dependent
| 2. Without T cell help (T cell independent)
100
Binding of what on B cells enhances their responses to antigen?
CR2
