2.4 Immunology Flashcards
(177 cards)
1
Q
What are the 2 types of cells of the immune system?
A
leukocytes
stem cells
2
Q
Where do leukocyres come from?
A
derived from bone marrow stem cells
3
Q
What are stem cells?
A
undifferentiated cells that can continually divide
4
Q
What does totally potent mean?
A
stem cells can differentiate into any type of cell
5
Q
What does multi-potent mean?
A
can differentiate into a certain type of cells
6
Q
what are the 2 types of stem cells?
A
embryonic
bone marrow
7
Q
What are the 2 types of leukocytes?
A
phagocytes and lymphocyte
8
Q
What do phagocytes do?
A
carry out phagocytosis - engulfs the pathogen
9
Q
How can you identify a neutraphil?
A
e-shaped nucleus
10
Q
How would you identify a macrophage?
A
c-shaped nucleus
11
Q
How would you identify a lymphocyte?
A
nucleus takes up most of the cell
12
Q
Why do phagocytes alone not provide immunity?
A
do not produce memory cells
13
Q
What are the two types of phagocytes?
A
macrophages and neutraphils
14
Q
What are the 2 types of lymphocytes?
A
B cells and T cells
15
Q
What do lymphocytes do?
A
capable of self and non-self recognition
kills pathogens and remebers them so provides immunity
16
Q
What type of cells are the non-specific immune response?
A
phagocytes
17
Q
What type of cells are involved in the specific immune response?
A
lymphocytes
18
Q
What do antigen presenting cells do?
A
once killed a pathogen, they can take the secretion of the antigen and present it to activate the immune system
19
Q
What type of cells are antigen presenting cells?
A
macrophages
B cells and T cells
20
Q
What antigen is on a B cell?
A
membrane-bound antibodies
21
Q
What antigen is on a T cell?
A
membrane bound protein
22
Q
What is an infection?
A
an interaction between the pathogen and the body’s various defence mechanisms
23
Q
What is immunity?
A
the ability of organisms to resist infection by protecting against disease-causing microorganisms or toxins
24
Q
What type of lymphocyte does cell mediated resposes involve?
A
T lymphocytes
25
What type of lymphocyte does the humoral resposne involve?
B lymphocytes
26
What can be identified from its antigens?
pathogens
non-self material
toxins
cancer cells
27
What is the issue with cell recognition and transplants?
the immune system recognises the transplant as non-self and attempts to destroy it
28
How do you minimise self cells attacking a transplant?
matching the transplant as close as possible to avoid tissue rejection
29
What drugs are used to minimise the immune response to a transplant?
immunosuppresant drugs
30
Why is there a lag time between exposure to pathogen and bodys defences?
clonal selection is occuring
31
What are the 2 non-specific responses?
physical / chemical barriers
phagocytosis
32
What are the 2 specific responses?
cell-mediated response
humoral response
33
What happens to lymphocytes that attach to the bodys own cells?
they either die or are suppressed
34
What is apoptosis?
programmed cell death
35
What are the 2 types of WBC?
lymphocytes and phagocytes
36
What is the process of phagocytosis?
1. the phagocyte is attracted to the pathogens by debris or toxins from pathogen
2. the phagocyte attaches to the pathogen by receptor binding points
3. phaocyte changes shape to engulf pathogen
4. lysosomes within phagocyte migrate towards pathogen to form a phagosome
5. lysosomes release lysozymes into phagosome
6. hydrolysis products are abosrbed by phagocyte
37
How is the phagocyte attracted to the pathogen?
by chemical products of the pathogen, it moves towards the pathogen down a conc grad
38
How does the phagocyte attach to the pathogen?
phagocyte has several receptors on its cell-surface membrane that attach to the chemicals on the pathogen's surface
39
What is an antigen?
any part of an organism or substance that is recognised as non-self by the immune system and stimulates an immune response
40
Where is the B lymphocytes produced?
bone marrow
41
Where are the T cells produced?
thymus gland
42
How can T cells find non-self cells?
phagocyte presents pathogen antigen
body cells presenting viral antigen
transplanted cells have different antigens
cancer cells antigens
43
What are antigen-presenting cells?
cells that display foreign antigens on their surface
44
What are the only antigens a T cell responds to?
antigens that are presented on a body cell
45
What is the process of cellular response?
1. pathogens invade body cells/ taken in by phagocytes
2. antigens are displayed on cell-surface of phagocyte
3. receptors of a specific Th cells fits onto the antigens
4. attachment activates the T cell to divide rapidly by mitosis - forms clones
5. T cells will differentiate into the following:
-remain as Th cells and stimulate B cells
- stimulate macrophages
- memory cells for that specific antigen
- cytotoxic T cells
46
What do the cloned T cells do?
develop memory cells
stimulate phagocytes
stimulate B cells to divide and secrete antibodies
activates cytotoxic T cells (Tc cells)
47
What are Th cells?
T helper cells
48
What do T helper cells do?
their receptors bind to the antigens and stimulate B cells
49
What are Tc cells?
cytotoxic T cells
50
What do cytotoxic T cells do?
kills abnormal cells and body cells that are infected by pathogens
51
How do cytotoxic T cells kill cells?
produces a protein called perforin that makes holes in the cell-surface membrane
52
What do B cells do?
produces a specific antibody that responds to one specific antigen
53
What is clonal selection?
The process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes.
54
What are the 2 types of cells that the B cell clones develop into?
plasma cells
memory cells
55
What do plasma cells do?
secrete antibodies into the blood plasma
56
What are the plasma cells responsible for?
the immediate defence of the body against infection
57
What is the primary immune response/
the initial production of antibodies and memory cells
58
Where do memory cells circulate?
in the blood and tissue fluid
59
What do memory cells do?
responsible in the secondary response - detect same antigen and divide rapidly into plasma cells and more memory cells
60
By what cell divison proces do B cells clone themselves?
mitosis
61
Describe the process of the humoural response?
1. T helper cells bind to antigen on the antigen-presenting cell
2. this Th cell stimulates a specific B cell
3. b cell divides by mitosis to give a clone of plasma cells others divide into memory cells
4. the cloned plasma cells release antibodies
62
What is an antibody?
a protein with a specific binding site synthesised by B cells
63
How does an antibody react with the antigens?
binds to them
64
How many polypeptide chains does an antibody have?
4
65
What are the long polypep chains in an antibody called?
heavy chains
66
What are the short polypep chains in an antibody called?
light chains
67
How does the antibody bind to the antigen?
by the antigen binding sites - complementary in shape to antigen
68
What is formed when an antibody binds to an antigen?
an antigen-antibody complex
69
What two regions are on a antibody?
variable region
constant region
70
What are the two ways an antibody prepares a bacteria cell for destruction?
causes agglutination of the bacterial cells
serve as markers
71
What is agglutination?
clumping together cells
72
Why does agglutination of cells make destruction of them easier?
easier for the phagocytes to locate them as they are less spread out in the body
73
How do antibodies serve as markers?
present the antigen on the surface and they stimulate phagocytes to engulf the cells which they are attached to
74
What is a monoclonal antibody?
a single type of antibody that can be isolated and cloned
75
What are the uses of monoclonal antibodies?
targeting medication to specific cell types
medical diagnosis
pregnancy tests/ lateral flow tests
vaccines
76
How are monoclonal antibodies used to treat cancer?
monoclonal antibodies are produced that are specific to antigen on cancer cells
antibodies are given to patient and attach themselves to the receptors on the cancer cells
attach to the surface of the cancer cells and block the chemical signals that stimulate their uncrontrollable growth
77
What is the advantage of using monoclonal antibodies to treat conditions?
they are not toxic
highly specific
lead to fewer side effects than other forms of therapy eg. chemo
78
What is indirect monoclonal antibody therapy?
attaching a radioactive or cytotoxic drug to monoclonal antibodies so killing the cells the antibody attaches to
79
What are cytotoxic drugs?
a drug that kills cells
80
What are monoclonal antibodies used to diagnose?
influenza
chlamydia
certain cancers
81
What hormone is found in the mothers urine while pregnant?
hCG
82
How do pregnancy tests work?
1. antibody are linked to coloured particles
2. if hCG is present it will bind to these antibodies
3. the hCG-antibody-colour complex will move alone the strip until it is trapped by an immobilised mAb creating the coloured line
4. behind this row of immobolised mAbs is another row which bind to any mAbs which don't have hCG attached - this is the control line
83
What is an issue with monoclonal antibodies?
they use mice to produce anitbodies and tumour cells - cancer must be induced
84
What is passive immunity?
where an individual receives antibodies from an external source. The antibodies are not made by the individual., theres no direct contact with the pathogen
85
What is an example of passive immunity?
immunity is acquired by a fetus when antibodies pass across the placenta from the mother
86
What is active immunity?
produced by stimulating the production of antibodies by the induvidual's own immun system, direct contact with the pathogen
87
What is natural active immunity?
results from an induvidual becoming infected under normal circumstances
88
What is artificial active immunity?
forms the basis of vaccination - inducing an immune response in an induvidual
89
What is vaccination?
the introduction of the appropriate disease antigens into the body either by injection or by mouth
90
What does a vaccine contain?
one or more types of antigen from the pathogen
91
What are vaccines used for (not treating disease)?
used as a precautionary measure to prevent induviduals contracting a disease
92
What factors does a successful vaccination programme depend on?
economic availability
side-effects
means of administration
possibility of herd immunity
93
Why mustn't a vaccine have bad side effects?
may discourage induviduals from being vaccinated
94
What does administrating the vaccine require?
staff training with appropriate skills
95
What is herd immunity?
when a sufficiently large proportion of the population has been vaccinated, making it difficult for a pathogen to spread within a population
96
Who might not be vaccinated?
babies
immunodeficient people
97
what might happen if someone who is immunodeficient is vaccinated?
the vaccine will fail to induce immunity
98
Why might a vaccine not eliminate a disease?
infection immediately after vaccination
mutation of pathogen
pathogens can hide
induviduals with ethical issues against vaccines
99
Why does infection immediately after vaccination reduce the vaccine affect?
their immunity levels are not high enough for the disease to be prevented so the vaccine is ineffective
100
What is antigenic variability?
the antigen on the surface of the pathogen change suddenly
101
What are some ethical reasons someone wont be vaccinated?
MMR
religion
medical reasons
102
What are the ethical issues of vaccines?
testing on animals
side-effects can be unknown - possible long-term harm
should they be compulsory for full success
religions
103
What does HIV stand for?
human immunodeficiency virus
104
What does HIV do?
causes AIDS
105
What does AIDS stand for?
acquired immune deficiency syndrome
106
What enzyme is present in HIV?
reverse transcriptase
107
What does reverse transcriptase in HIV do?
catalyses the production of DNA from RNA
108
What is a retrovirus?
a group of viruses that have the ability to make DNA from RNA
109
What is the process of replication of HIV?
1. HIV enters the bloodstream and circulates around the body
2. protein on HIV readily binds to protein CD4 - most likely on T helper cells
3.capsid fuses with cell-surface membrane, the RNA and enzymes of HIV enter the Th
4. Reverse transcipt's role
5. newly made DNA is moved into T help cell nucleus and inserted into T cells DNA
6. HIV DNA in nucleus creates mRNA using cell's enzymes
7. mRNA leaves nucleus via nuclear pore and uses cell's protein synthesis mechanism to form new HIV particles
8. HIV particles break away from cells membrane forming the lipid envelope
110
What does mRNA do in HIV replication?
contains the instructions for making new viral proteins and the RNA to go into the new HIV
111
How does HIV cause AIDS?
by killing or interfering with the normal functioning of T helper cells so cannot stimulate B cells to produce antibodies or cytotoxic T cells
112
What is likely to cause death with AIDS?
secondary diseases because of inadequete immune response
eg - lung infections
113
What does the ELISA test do?
uses proteins to detect the presence of a protein in a sample but also the quantity of the protein
114
How do antibiotics work on bacterial cells?
weakens the cell walls made of murein which makes the walls unable to withstand the pressure of water entering the cell
so the cell burts and the bacterium dies
115
Why dont antibiotics work on viruses?
there are no metabollic mechanisms or cell structures that the antibiotic will interupt
protein coat instead of murein so there are no sites where the antibiotic could work
visues within a host cell cannot be reached by antibiotics
116
What is the process of maturation of T cells?
1. in bone marrow, immature T cells divide by mitosis
2. in the thyymus, each T cell matures and the T receptors are produced
3. mature T cells ciculate, same as Th and some as Tc - each have a different T cell receptor
117
What is the structure of a T cell receptor?
it is a protein so:
tertiary structure with h bonds, disulphide bridges and ionic bonds betweenR groups
118
What is the maturation of B cells?
1. in bone marrow, immature B cells divide by mitosis
2. still in bone marrow, each B cell matures - production of antibody receptors
3. Mature B cells circulate and concentrate in the liver and spleen, each B cell has a different antibody receptor
119
What type of protein are antibody receptors?
globular protein
120
What is the 1st line of defence?
barriers
121
What are examples of Barriers?
stomach acid
mucus
skin
tears, saliva and sweat
122
What does stomach acid do in immunity?
denatures and breaks down proteins in pathogen
123
What do tears, sweat and saliva all contain?
lysosymes - digest bacterial cell walls
124
What is the 2nd line of defence?
non-specific immune system
125
What are examples of non-specific immune system?
phagocytosis
blood clotting
fever
inflammation
126
What does inflammation do in immunity?
secretes chemicals that increase blood flow for more white blood cells circulating
127
What does blood clotting do in immunity?
prevents the entry of pathogens
128
What does a fever do in immunity?
trys to denature the enzymes and proteins or inhibit enzymes
129
What is the 3rd line of defence?
specific immune system
130
What are the 2 types of specfic immune response?
cellular response and humoral response
131
What happens after antigen presentation?
clonal selection and expansion
132
What is resistance?
the tolerance to withstand chemicals
133
What are examples of antigen presenting cells?
viral capsid
transplanted organs
toxins
bacterial antigens
macrophages
infected body cell
cancerous cell
134
What is clonal selection?
he process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes.
135
What is clonal expansion?
The production of many genetically identical daughter cells through cell division of the activated B or T lymphocyte after clonal selection.
136
What do T helper cells do in the cellular response?
bind to antigen on antigen presenting cell (clonal selection)
divide by mitosis (clonal expansion)
secretes cytokenes to stimulate B cells
some others divide to form memory cells
137
What do cytokenes do?
stimulate B cells to divide and form plasma cells and memory cells
138
What do cytotoxic T cells do in the cellular response?
complementray cytotoxic T cells binds to antigen on antigen presenting cell and activated by a T helper cell
divides by mitosis
releases Perforin proteins - inserted into infected cell's membrane creating a pore - water enters by osmosis = cell lysis
139
What is the role of the memory T cells in the cellular response?
remain in the blood for decades
can identify the same antigen more quickly at next exposure
140
Describe the humoural response in the secondary immune response?
the antigen enters the body for second time
memory cells that were produced in primary response, respond and divide to form more plasma cells
plasma cells secrete antibodies
141
What is the role of B cells in the humoral response?
complementary B cells binds to presented antigen (clonal selection)
clonal expansion
differentiates into plasma B cells and some memory cells
142
What is the role of plasma B cells in the humoral response?
produces antibodies
143
What organelles are in a plasma B cell and their role?
packed with RER - synthesis of antibodies
golgi - packages and secretes antibodies
mitochondria - produces ATP for synthesis and exocytosis
144
Why is there a lag time for the primary response?
clonal selection and clonal expansion taking place
145
Describe the secondary resposne in terms of the graph
it has a much faster antibody secretion
there is a higher max conc of antibodies that lasts longer
146
What are the 2 circumstances that there will be no secondary response to a pathogen?
1.highly viralent pathogen that is fatal at 1st exposure (if the antigen has attached to the cells quicker than the lag time before the 1st response)
2. antigenic variability on the same pathogen - mutation of antigen
147
What type of protein structure is an antibody?
quaternery - globular
148
What bond joins the polypeptide chains together in an antibody?
disulphide bridges
149
Which region of the antibody has a different primary structure?
the variable region
150
What are all the actions of an antibody?
cause bacterial lysis
prevent pathogen/ toxins entering host cells
coats pathogen to aid phagocytosis
deactivates flagella to aid phagocytosis
causes pathogen to agglutinate
151
What is the method of forming monoclonal antibodies?
1. inject small mammel with antigen to stimulate humoural response
2. isolate the plasma B cells that secrete the antibodies needed for this antigen
3. fuse plasma cell with myeloma cell to form a hybridoma
4. isolate hybridoma that produces the correct antibody
5. clone the specific hybridoma to produce many monoclonal antibodies
152
What is direct monoclonal antibody (mAb) therapy?
mAbs are specific to patient's cancer cells
it blocks the chemical signalling for uncontrolled mitosis by binding to the receptor of the patient's cancer cell
153
What is indirect mAb therapy?
mAb has cytotoxic drug attached - magic bullet
attaches to cancer cell antigens
causes apoptosis of cancer cell
154
What are the advantages of using mAb as a treatment for cancer?
mAb are non-toxic
mAb are specific
can use a lower dosage - fewer side effects and cheaper
155
What does the ELISA test stand for?
Enzyme Linked ImmunoSorbent Assay
156
How does the direct Elisa test work?
1. well in test plate to attache mAb specific to antigen being tested
2. wash test plate - to remove unnattached mAbs
3. add patient's blood sample, if antigen present they will bind to mAb
4. wash - to removed unbinded antigens
5. add 2nd mAb specific to antigen, that has an enzyme attached
6. wash - remove unattached 2nd mAb
7.add a colourless subrate that the enzyme will break down to a coloured product - a visible colour change occurs - shows the conc of antigen
157
What are the ethical issues of mAbs?
small mammels are used to produce mAbs and Myloma cells - need to induce cancer to do so
requires informed consent from patients to be used
failed drug trials
158
What is natural immunity?
obtain immunity through life processes
159
What is artificial immunity?
immunity from deliberate exposure
160
What is active immunity?
lymphocytes activated and antibodies are produced
161
What is passive immunity?
lymphocytes are not activated and no antibodies are produced
162
What is an eg of natural active immunity?
infection by pathogen
163
What is an eg of active artificial immuntiy?
antigen injection
164
What is an eg of natural passive immunity?
breastfeeding and across the placenta
165
What is an eg of artifical passive immunity?
antibody injection
166
Why would an antibody injection be used instead of an antigen injection?
if a faster a response is needed to a highly virralent pathogen
common for armed forces and medical staff for travelling to different countaries
167
What could be in a vaccine?
dead/ inactive pathogen
attenuated (weakened) pathogen
antibodies
antigens
live pathogen
toxoids
168
What is needed for a vaccination to be successful?
antigen should be highly immunogenic = triggers a strong immune response and produces a high conc of antibodies
there should only be one antigenic type of pathogen
169
why is using a live pathogen in a vaccine more effective?
there is a continual exposure to antigen
170
Why is using dead pathogens less effective in vaccines?
limited exposure to antigens
171
Why are booster vaccines used?
to produce the secondary response
they are required when memory cells are short lived
172
What is herd immunity?
occurs when a large proportion of a population are vaccinated against a disease which prevents the spread of the disease to unvaccinated individuals
173
What is ring immunity?
f a person is exposed to a virus, a vaccine for that virus is given to others who are in close contact with that person, such as close family and friends.
174
Who linked the MMR vaccine with autism?
Andrew wakefeild
175
What is a retrovirus?
a virus that has RNA and reverse transcriptase
176
Why does the T helper cell shrink after HIV replication?
HIV takes away the cell membrane for its own membrane
177
How can children be born with HIV?
the antibodies and virus can cross through the placenta
