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Immunology Flashcards

1
Q

What is the immune response?

A

When the body is invaded by any pathogen, a series of responses ensure that the pathogen is rapidly identified as non self, and destroyed before too much damage is caused to the affected organism.

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2
Q

2 ways that pathogens cause harm /disease?

A

Pathogens can produce toxins which can directly damage cells
Pathogens can sometimes replicate and destroy host cells

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3
Q

Antigen definition

A

An antigen is a molecule that stimulates an immune response that results in the production of a specific antibody.

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4
Q

What happens when antigens are not recognised by our immune system?

A

The body will treat that cell/pathogen as non-self and initiate an immune response which will lead to the destruction of the pathogen

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5
Q

What are examples of antigens

A

Glycolipids
Glycoproteins

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6
Q

Phagocytes

A

Phagocytes are a groups of white blood cells which can distinguish between cells which do or do not display the self-antigens.
Phagocytes will engulf and destroy any cell that presents a non-self-antigen

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7
Q

Phagocytosis key stages

A

1) Pathogen is engulfed by the phagocyte.
2) Engulfed pathogen enters the cytoplasm of the phagocyte in a vesicle.
3) Lysosomes fuse with the vesicle releasing lysozymes
4) Lysozymes hydrolyse the pathogen.
5) Waste materials are released from the cell by exocytosis and the phagocyte becomes an antigen presenting cell

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8
Q

What type of process is phagocytosis?

A

Non-specific
It works the same for any cell / pathogen that displays a non-self antigen

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9
Q

What does a specific response entail?

A

A specific response to a specific antigen on the surface of a cell or pathogen that has been recognised as non-self.

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10
Q

Response of T Lymphocytes is what?

A

Cell-mediated immunity

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11
Q

Which type of response are T lymphocytes responsible for?

A

Primary response

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12
Q

What does the cell-mediated response include (steps)?

A

1) Phagocyte undergoes phagocytosis and is now antigen presenting
2) The T helper cell with bind to the specific antigen with its specific complementary receptors
3) T helper cell becomes activated
4) T helper cell undergoes clonal expansion

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13
Q

What can the T helper cells differentiate into during clonal expansion?

A

T helper cells
T cytoxic killer cells
T memory cells

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14
Q

T helper cell role

A

1) Specific T helper cell binds to specific antigen on presenting cell
2) Releases cytokines which attract phagocytes to the site of infection
3) Releases cytokines that activate T cytoxic killer cells
4) Activates a specific complementary B cell
5) Form memory T helper cells

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15
Q

What does the releasing of cytoxines do?

A

Attract phagocytes to the site of infection
Activate T killer cytoxic cells

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16
Q

T cytoxic killer cell role

A

Locate and destroy body cells that are infected by the specific antigen
Binds to antigen presenting cells
Releases perforin which creates holes in the cell surface membrane which kills the antigen presenting cell

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17
Q

What does the releasing of perforin do?

A

Creates holes in the cell surface membrane which kills the antigen presenting cell

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18
Q

What does the T cytoxic killer cell release?

A

Perforin

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19
Q

What type of response is the activation of B cells?

A

Humoral response

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20
Q

What does the humoral response involve?

A

The activation of B cells to produce antibodies.
B cells must be stimulated by their complementary TH cell by the release of cytokines.

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21
Q

B cell activation steps

A
  1. Specific T helper cell which is complementary to the specific B cell locates and activates the B cell.
  2. The T helper cell releases cytoxines which cause the B cell to undergo clonal expansion
  3. The B cells either differentiate into plasma cells or B memory cells
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22
Q

Plasma cells

A

Produce and secrete vast quantaties of antibodies

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23
Q

B memory cells

A

Remain in the body to respond to a pathogen rapidly and effectively if there is a future re-infection

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24
Q

What is an antibody?

A

A protein which has specific binding sites that bind to an antigen produced by a plasma cell. It is made in response to the foreign antigen

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25
Structure of an antibody
Light chains Heavy chains Variable region Constant region Antigen binding site
26
Constant region in an antibody
The main part of the antibody
27
Variable region in an antibody
Have a different primary structure, therefore have a different and specific tertiary structure to a specific antigen, as it the antibody's binding site
28
What is produced when an antibody has been bound to an antigen?
Antibody-antigen complex
29
Agglutination
Specific antibodies bind to specific antigens and clumps them together, attracting phagocytes to engulf them
30
Antigenic variability
Gene mutations in pathogens may lead to a change in tertiary structure of antigens specific to the B cell SO memory B cell antibodies will no longer be complementary to the mutated pathogen so no antigen-antibody complex will form and the individual will not be able to initiate a secondary response.
31
Why is the secondary response effective?
The secondary immune response is effective as most pathogens have the same antigens on their surface, and so are recognised by memory cells when re-infection occurs.
32
What is the secondary response?
The activation of memory cells to produce antibodies. It is rapid
33
What does the release of cytokines do?
Attract phagocytes to site of infection Attract B cells to activate them Activate T cytoxic killer cells
34
What is the cell mediated response?
Response of T lymphocytes
35
Give steps of clonal selection in T helper cells
A specific T helper cell binds to presented antigen via its complementary receptor T helper cell is activated and clones to produce many T helper cells with complementary receptors to the antigen
36
What is opsonisation?
Antibodies marking pathogens so phagocytes recognise and destroy the pathogens more effectively
37
What is lysis?
Antibodies bind to antigens and lead to destruction of the pathogen's membrane
38
How do antibodies assist in the destruction of pathogens?
Agglutination Opsonisation Lysis Prevent pathogen replicaton
39
What is the humoral response?
Reponse of B lymphocytes
40
What happens if memory cells encouter the antigen again?
They are rapidly activated by cytokines and divide rapidly by mitosis The genetically identical cloned memory cells differentiate into more plasma and B memory cells The plasma cells produce vast numbers of the specific antibodies for the invading pathogen in a short period of time
41
What is the secondary response?
The activation of memory cells to produce antibodies
42
How can the secondary response be described?
Rapid and extensive
43
Why is the secondary response rapid and extensive?
The antigen is normally eliminated before it can cause disease or any symptoms to develop
44
What is antigenic variability?
Gene mutations in pathogens lead to a change in tertiary structure of antigens specific to the B cell Therefore, memory B cell antibodies will no longer be complementary to the mutated pathogen so no antibody-antigen complex can be formed and the individual will not be able to initiate a secondary response
45
Why is the secondary immune response effective?
Most pathogens have the same antigens on their surface and so are recognised by memory cells when re-infection occurs
46
Why is it hard to produce vaccines against certain pathogens?
Because of Antigenic variability
47
Why is immunity important?
It stops individuals and populations from suffering from disease.
48
What are features of passive immunity?
Short term No exposures to antigen Antibodies are given No memory cells are produced Fast acting
49
What is a natural form of passive immunity?
Antibodies being transferred to a baby via breast feeding
50
What is an artificial form of passive immunity?
Pre-synthesised antibodies are injected into the blood
51
What are features of active immunity?
Exposure to antigen Antibodies are produced Mmeory cells are produced Long term Take time to develop
52
What is a natural form of active immunity?
Natural production of antibodies following infection
53
What is an artificial form of active immunity?
From vaccination ie Covid
54
What do vaccines contain?
Antigens from dead, weakened or heat treated pathogens
55
What happens when you get vaccinated? (active immunity)
Phagocytosis occurs A specific T helper cell binds to the antigen on phagocyte The specific T helper cell stimulates a specific B cell by releases cytokines B cell undergoes clonal expansion to produce B memory and plasma cells Plasma cells produce antibodies
56
What are vaccines not effective against?
Pathogens which show antigenic variability
57
What are some uses of monoclonal antibodies?
Research Diagnosis Targeting drugs Killing specific cells
58
What is the indirect ELISA?
Used to determine the presence of the antibody
59
What is the sandwich ELISA?
Used to determine the presence of the antigen
60
Describe the Indirect ELISA test
1. Antigen is coated onto a plate in a well Wash 2. Specific primary antibody binds to antigen Wash 3. Enzyme linked secondary antibody binds to primary antibody Wash to remove unbound secondary antibodies 4. Colourless substrate solution is added 5. If the enzyme is present, there will be a colour change
61
How can you test the colour change in the ELISA test?
Using a colourimeter or colour chart
62
What does a more intense colour mean in the ELISA test?
The more intense the colour, the more enzymes, so the more antibodies
63
What does the ELISA test depend on?
Whether the individual's body has produced the antibodies
64
If unbound enzymes remain in the sample after washing, what does this indicate?
A false positive
65
What is the latent period?
The time between getting infected and producing antibodies
66
Describe the Sandwich ELISA test
1. Primary antibody is coated onto a plate in a well Wash 2. Add an antigen to be measured Wash 3. Add enzyme linked secondary antibody Wash to remove unbound enzyme linked antibody 4. Add colourless substrate and measure colour
67
What is the colour in the Sandwich ELISA test proportionate to
The concentration of antigen
68
What does HIV stand for?
Human Immodeficiency Virus
69
What is the structure of HIV?
Attachment proteins Lipid Envelope Reverse Transcriptase Capsid HIV RNA
70
What is reverse transcriptase used for in HIV?
So that the host cells can turn HIV RNA into DNA by reverse transcription
71
What type of virus is HIV?
Retro virus
72
What is a retro virus?
A virus that has single stranded DNA
73
Describe HIV replication using T helper cells
1. Attachment proteins on HIV binds with a specific receptor on TH cells. 2. Capsid fuses with cell-surface membrane and releases Viral RNA and enzymes into the helper TH cell. 3. RNA converted into DNA using reverse transcriptase; 4. DNA inserted into helper T cell 5. DNA transcribed into HIV mRNA; 6. HIV mRNA translated into HIV proteins
74
What does HIV replication lead to over time?
A reduction in the number of T helper cells
75
How can AIDS be screened for?
Checking the number of T helper cells
76
How do antibiotics work?
They prevent bacteria making a normal cell wall by targeting 70s ribosomes This means that the bacteria are unable to resist osmotic pressure and the cells burst due to an increase in cell volume of water by osmosis
77
Why doen't antibiotics work on viruses?
They have a capsid which doesn't allow antibiotics to act on viruses as they do on bacteria

Biology (25 decks)

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