introduction to immunology Flashcards
1
Q
what are the two types of immunity?
A
innate immunity
adaptive immunity
2
Q
describe innate immunity
A
non-specific, instinctive, does not depend on lymphocytes
3
Q
describe adaptive immunity
A
specific ‘acquired’ immunity, requires lymphocytes, antibodies
4
Q
what does humoral mean?
A
Is made up of cells and soluble proteins
5
Q
what is a Haematopoietic pluripotent stem cell (haemocytoblast)
A
he stem cell that every blood cell in the body originates from
6
Q
define polymorphonuclear
A
more than one nucleus
7
Q
what do polymorphonuclear leukocytes include?
A
neutrophils, eosinophils and basophils
8
Q
define mononuclear leukocytes
A
one nucleus
9
Q
what do mononuclear leukocytes include?
A
monocytes (kidney shaped nuclei), T-cells and B-cells (lymphocytes)
10
Q
what are the cells involved in the immune system ?
A
1.neutrophils
2. monocytes
3.macrophages
4. basophil
5.mast cell
6. t lymphocytes
7. b lymphocytes
8. natural killer cells
11
Q
what is the importance of neutrophils?
A
Plays an important role in innate immunity (phagocytosis)
12
Q
what are the 2 main intracellular granules- neutrophils?
A
Primary lysosomes – can kill microbes by secreting toxic substances
Secondary granules
13
Q
what is the importance of monocytes?
A
Plays an important role in innate AND adaptive immunity (phagocytosis and Ag presentation)
14
Q
what do monocytes differentiate into?
A
macrophages in the tissues
15
Q
what Is the main role of monocytes?
A
remove anything foreign (microbes) or dead
16
Q
what is the importance of macrophages?
A
Play important role in innate and adaptive immunity (phagocytosis and Ag presentation)
17
Q
where do you find macrophages?
A
Reside in tissues, lifespan – months/years e.g. Kupffer cells – liver, microglia – brain
18
Q
what is the main role of macrophages
A
Most often first line of non-self recognition
Main role – remove foreign (microbes) and self (dead/tumour cells)
( also present Ag to T cells)
19
Q
what is eosinophil mainly associated with?
A
Mainly associated with parasitic infections and allergic reactions
20
Q
what is the lifespan of eosinophil?
A
Lifespan 8-12 days
21
Q
what I the stain for eosinophil?
A
Granules stain for acidic dyes (eosin)
22
Q
what does eosinophil do?
A
Activates neutrophils, induces histamine release from mast cells and provokes bronchospasm
23
Q
what is basophil mainly involved in?
A
Mainly involved in immunity to parasitic infections and allergic reactions
24
Q
what is the lifespan of basophil?
A
2 days
25
what is the stain for basophil?
Granules stain for basic dyes
26
wha do basophils do?
Binding of IgE to receptor causes de-granulation releasing histamine – main cause of allergic reactions
( they are similar to mast cells)
27
where are mast cells found? precursor?
Only in tissues (precursor in blood)
28
what are mast cells similar to?
basophils
29
what do mast cells do?
Binding to IgE to receptor causes de-granulation releasing histamine – main cause of allergic reactions
30
what is the major role of T lymphocytes?
Play major role in adaptive immunity
31
what is the lifespan for T lymphocytes?
hours-years
32
where to T lymphocytes mature?
in thymus
33
where are T lymphocytes found?
found in blood, lymph nodes and spleen
34
what do T lymphocytes generally do?
Recognise peptide Ag displayed presenting cells (APC)
35
what are the 4 main types of T cells?
T helper 1
T helper 2
Cytotoxic T cell
T regulator
36
what does t helper 1 do?
(CD4 – help immune response intracellular pathogens)
37
what does t helper 2 do?
(CD4 – help produce antibodies extracellular pathogens)
38
what do cytotoxic T cells do?
(CD8 – can kill cells directly)
39
what do T regulator cells do?
regulate immune responses
40
what do B lymphocytes cells play a major role in?
Play major role in adaptive immunity
41
what is the lifespan of B lymphocytes?
lifespan hours- years
42
where do B lymphocytes
mature?
in bone marrow
43
what do b lymphocytes recognise?
Recognise Ag displayed by antigen presenting cells (APC)
44
where do B lymphocytes differentiate?
Differentiate into plasma cells that make antibodies
45
where are B lymphocytes found?
Found in blood, lymph nodes and spleen
46
what do natural killer cells account for?
Account for 15% of lymphocytes
47
where are natural killer cells found?
Found in spleen, tissues
48
what do natural killer cells recognise ?
Virus infected cells
Tumours cells
49
how do natural killer cells kill?
by apoptosis
50
what are the soluble factors?
complement
antibodies
cytokines
chemokines
51
what is a classic complement?
Ab bound to microbe
52
what is alternative complement?
c binds to microbe
53
what are the three modes of action of complements?
Direct lysis
Attract more leukocytes to site of infection
Coat invading organisms
54
what are antibodies?
Hallmark of adaptive immunity – they bind specifically to antigen (Ag)
Immunoglobulin’s are soluble
55
what are the 5 distinct classes of it's and glycoproteins?
IgG
IgA
IgM
IgD
IgE
56
Describe IgG
Predominant in human serum, 70-75% of total Ig in serum
Crosses placenta
57
describe IgA
Accounts for 15% of Ig in serum
Predominant Ig in mucous secretions such as saliva, milk and bronchiolar secretions.
58
describe IgM
Accounts for 10% of Ig in serum
Mainly found in blood (they’re big so they can’t cross the endothelium)
Mainly primary response, initial contact with Ag
59
describe IgD
Accounts for 1% of Ig in serum
A transmembrane monomeric form is present on mature B cells
60
describe IgE
Accounts for ~0.05% of Ig in serum
Basophils and mast cells express an IgE-specific receptor that has high affinity for IgE – binding triggers release of histamine
Associated with allergic response and defence against parasitic infections
61
define antibody
protein produced in response to an antigen. It can only bind with the antigen that induced its formation – i.e. specificity.
62
define antigens
a molecule that reacts with preformed antibody and specific receptors on T and B cells.
63
define epitope
the part of the antigen that binds to the antibody/ receptor binding site
64
define affinity
measure of binding strength between an epitope and an antibody binding site. The higher the affinity the better.
65
define cytokines
proteins secreted by immune and non-immune cells. Substances produced by one cell that influence the behaviour of another, thus effecting intercellular communication.
66
what are the different types of cytokines?
interferons
interleukins
colony stimulating factors
tumour necrosis factors
67
what to do interferons?
induce a state of antiviral resistance in uninfected cells and limit the spread of viral infection
68
what produces interleukins?
produced by many cells, over 30 types.
69
what can interleukins cause?
Can cause cells to divide, to differentiate and to secrete factors
70
what are colony stimulating factors involved in?
Can cause cells to divide, to differentiate and to secrete factors
71
what do tumour necrosis factors do?
Mediate inflammation and cytotoxic reactions
72
what do chemokines do?
direct movement of leukocytes from the blood stream into the tissues or lymph organs by binding to specific receptors on cells.
They attract leukocytes to sites of infection/inflammation – like magnets
73
describe innate ( non specific) defence mechanisms
-it is the 1st line of defence
-Provides barrier to antigen
-Is present from birth
-No memory
-Does not require lymphocytes
74
describe adaptive ( specific) defence mechanisms
-Response specific to antigen
-Memory to specific antigen
-Quicker response
-Requires lymphocytes
75
describe innate immunity
-Effective but limited
-Can be evaded
-Primitive (spread across species)
-Instinctive response
-No long lasting memory
76
what does innate immunity include?
Physical and chemical barriers
Phagocytic cells (neutrophils and macrophages)
Serum proteins (complement, acute phase)
77
what are the anatomical barriers? what do they each do?
-Skin – dermis and epidermis
-Sebum (skin secretions)
-Intact skin – prevents penetration, prevents growth
78
what are the physical barriers / mucous membranes?
Saliva
Tears – lysozyme in tears and other secretions
Low pH and commensals of vagina
Mucous secretions
Mucous – entrapment
Cilia – beating removes microbes
Commensal colonies – attachment, nutrients
79
what are the physiological barriers?
Temperature – chickens have high body temperature and are Anthrax resistant
Fever response inhibits micro-organism growth
pH
Gastric acidity – neonate stomach less acidic than adult so susceptible to infection
80
what are the hallmarks for immunity?
Primitive (spread across species)
Un-learned/ instinctive response
Doesn’t depend on immune recognition by lymphocytes
Does not have long lasting memory
81
define inflammation
: a series of reactions that brings cells and molecule of the immune system to sites of infection or damage
82
what is the immune response to a barrier being breached ( tissue damage or infection)?
1.Stop bleeding (coagulation)
2.Acute inflammation (leukocyte recruitment)
3.Kill pathogens, neutralise toxins, limit pathogen spread
4.Clear pathogens/ dead cells (phagocytosis)
5.Proliferation of cells to repair damage
6.Remove blood clot – remodel extracellular matrix
7.Re-establish normal structure/ function of tissue
83
define extravasion
a discharge or escape, as of blood, from a vessel into the tissues. Usually lymph from blood into tissues
84
hallmarks for inflammation
Increased blood supply
Increased vascular permeability
Increased leukocyte trans-endothelial migration ‘extravasation’
85
define acute inflammation
complete elimination of a pathogen followed by resolution of damage, disappearances of leukocytes and full regeneration of tissue (resolution – returns to normal homeostatic function)
86
define chronic inflammation
persistent, un-resolved inflammation
87
what can C' complement do?
Lyse microbes directly (membrane attack complex)
Increase chemotaxis
Opsonisation (C3b – important to remember)
88
describe the 6 steps of phagocytosis
Binding
Engulfment
Phagosome formation
Lysosome fusion (phagolysosome)
Membrane disruption
Antigen presentation/ secretion
89
describe adaptive immunity
Microbes evade innate immunity
Intracellular viruses and bacteria hide from innate immunity
Need memory to specific antigen
90
Cell mediated
T cells – intracellular microbes
91
Humoral (Ab)
B cells – extracellular microbes
92
what do major histocompatibility complexes do?
Display peptide from self OR non-self proteins (e.g. degraded microbial proteins) on the cell surface – invasion alert
93
MHC 1
glycoproteins on all nucleated cells
94
MHC II
– glycoproteins only on APC
95
MHC III
code for secreted proteins
96
Intrinsic (intracellular)
class I (all cells) – Tc (CD8) – kill infected cell with intracellular pathogen
97
Extrinsic (extracellular)
class II (APC only) – Th (CD4) – help B cell make Ab to extracellular pathogen
98
describe what is included in cell mediated immunity?
Antigen presenting cells (APC)
Macrophages
Dendritic cells
B cells
T cells
Requires intimate cell to cell contact
Control Ab responses via contact with B cells
Directly recognise and kill viral infected cells
99
what other cells/ things does cell mediated immunity require?
Major histocompatibility complex (MHC)
Intrinsic (endogenous) antigens
Extrinsic (exogenous) antigens
Recognise self or non-self
100
what to T cells respond to?
Only respond to intracellular presented antigens
101
describe T cell selection
T cells recognise self are killed in the foetal thymus as they matur
102
provide a summary of B cell activation ( 5 steps)
1. B cells become activated upon binding with an antigen. 2. These then go to the lymph nodes where clonal expansion takes place with the cells differentiating into plasma cells.
3. These secrete Ab (usually IgM) which later turn into IgG. 4. B cells divide – clonal expansion and differentiate into plasma cells and memory B cells.
5. Re-stimulation of memory B cells lead to secondary response.
