11.1 Antibody production and vaccination Flashcards
(94 cards)
1
Q
Simplified diagram showing some components of the immune system
A
2
Q
What does the surface of our cells contain?
A
Large carbohydrates, glycoproteins and other polypeptides that can be recognised by our own immune system as self.
3
Q
What organisms/non-organisms can have antigens on their surface?
A
Foreign cells such as bacteria, viruses, parasites, cancer cells and other pathogens also have an array of molecules on their surfaces that can potentially act as antigens.
4
Q
What is an antigen?
A
Any molecule that can trigger an immune response, leading to the generation of antibodies.
5
Q
How does the immune system respond to antigens?
A
The immune system can recognise antigens as ‘non-self’ and mount an immune response against them.
6
Q
Every organism has ___ on the surface of its cells.
A
Unique molecules
7
Q
The unique molecules that each organism has on the surface of its cells help ___
A
The immune system to recognise the cells as self.
8
Q
Diagram of the SARS virus, showing glycoproteins, which act as antigens
A
9
Q
Diagram showing some of the substances, cells, or entities that can be recognized as non-self/ possible origin of antigens
A
10
Q
What is the basis for the ABO blood group system?
A
The presence of cell-surface antigens.
11
Q
What do all red blood cells have on their surface regardless of blood type?
A
Antigen H
12
Q
Antigen H does not ___
A
Trigger an immune response.
13
Q
How are blood groups produced?
A
- Different molecules can be added to antigen H to produce blood groups A and B.
- For blood group A, N-acetylgalactosamine is added, for blood group B, galactose is added. Blood group AB has both modified antigens.
14
Q
Against which antigens on the surface of red blood cells does the immune system form antibodies and why?
A
- The immune system forms antibodies against whichever ABO blood group antigens are not found on the individual’s RBCs.
- Thus, a group A individual will have anti-B antibodies and a group B individual will have anti-A antibodies.
- If a foreign antigen is introduced, for example, if an individual with blood type A receives blood type B during a transfusion, anti-B antibodies will be produced and agglutination will occur.
15
Q
What is agglutination?
A
The clumping of a liquid, in this case, blood.
16
Q
What is hemolysis?
A
The rupture of the red blood cell’s membrane, leading to the release of the hemoglobin and other internal components into the surrounding fluid.
17
Q
What will agglutination lead to?
A
Hemolysis (‘rupturing’ of blood cells) and may result in the death of the patient.
18
Q
Diagram showing all the possible combinations between donors of blood (top row) and recipients (left column), as well as the resulting reaction.
It also shows that somebody who is blood group O is a universal donor.
A
19
Q
Diagram of agglutination in the blood
A
20
Q
The transfusion of type A blood to a person who has type O blood would result in ___
A
The recipient’s anti-A antibodies clumping the donated red blood cells.
21
Q
What happens once a pathogen or another antigen enters the body and why?
A
- It triggers a response.
- The body needs to make sure that the infection will be contained as quickly as possible, as well ensuring that it can recognize and deal with such an infection if it recurs.
22
Q
Diagram showing an overview of the immune response
A
.
23
Q
Steps of the immune response
A
- The antigen is quickly ingested (via phagocytosis) by macrophages and B cells.
- Both process the antigen and present it on their surface.
- The macrophage (now called an antigen-presenting cell) interacts with a helper T cell.
- This activates the helper T cell.
- The activated helper T cell interacts with the B cell that has the antigen on its surface (shown in step 2 in the diagram) and activates it.
- The activated B cell rapidly divides by mitosis to form clones of plasma cells and memory cells.
- The plasma cells possess lots of rough endoplasmic reticulum and a well-developed Golgi apparatus making them well-suited for producing antibodies (of one specific type) against the antigen.
24
Q
Why are antibodies and memory cells important in the body?
A
- The antibodies help to destroy the antigen.
- To be immune against a certain infectious pathogen, the body needs antibodies that are already in your blood, or to have memory cells that produce a specific antibody against this type of infective agent.
- Vaccination can achieve both of these results.
25
Binding of B cells
- Only the B cells with receptors (antibodies) that can bind the antigen will take in the antigen for processing.
- This ensures that only the B cells that can produce the specific antibodies against the antigen are selected for cloning in later stages.
26
The receptors on B cells bind to ___
Antigens
27
Cells activated by antigen exposure lead to the production of ___
-Plasma cells that secrete antibodies for the antigen.
-Once activated by exposure to the antigen and the interaction with the activated helper T cell, some B cells turn into plasma cells that start producing vast quantities of antibodies.
28
What happens once the immune system has reacted to the invasion of an antigen?
Antibodies (proteins that bind to foreign substances) are produced.
29
Diagram of an antibody
30
Describe the structure of an antibody
- An antibody has constant and variable regions.
- The variable region is the part of the antibody which is highly specific to a particular antigen.
- The long and short chains are held together by disulfide bonds.
31
What are antibodies used for once they are produced?
They are used in a number of ways to aid the destruction of pathogens.
32
Diagram showing the various functions of antibodies
33
What is the difference between antibodies and antigens?
- Antibodies are proteins produced by plasma cells (a B cell originally) in response to an antigenic reaction.
- Antigens are any entities that trigger an immune response. This could be a protein, virus, bacterium, parasite, fungus, or large glycoprotein.
34
Outline four modes of antibody action
- Agglutination – Antibodies cause the sticking together of pathogens by attaching to the antigens on the surface. These clumped masses of pathogens are then easily ingested and destroyed by phagocytes. The large agglutinated mass can be filtered by the lymphatic system and then phagocytized.
- Opsonization – Antibodies make pathogens recognizable by binding to them and linking them to phagocytes.
- Neutralization of toxins – Antibodies bind to toxins produced by pathogens in the blood plasma, preventing them from affecting susceptible cells.
- Neutralisation of viruses and bacteria – Antibodies can bind to the surface of viruses, preventing them from entering host cells.
- Complement activation – The complement system is a collection of proteins that ultimately leads to the perforation of the membranes of pathogens. Antibodies bound to the surface of a pathogen activate a complement cascade, which leads to the formation of a “membrane attack complex” that forms a pore in the membrane of the pathogen allowing water and ions to enter the cell, causing the cell to lyse.
35
Diagram showing antibody actions
36
Why is the chance that some childhood diseases, such as measles or chickenpox, would affect you later in life minimal?
Once exposed to an antigen, for example the virus that caused measles, your body produces antibodies and memory cells.
37
What is a primary response?
The immune response triggered on the first encounter of the body with an antigen.
38
What happens following the primary response?
Following the primary response, memory cells that are produced ensure that, if there is another infection with the same pathogen, your body can react very quickly to this threat.
39
What is the secondary response?
The immune response stimulated on the second exposure to the same antigen.
40
Graph showing the primary and secondary immune response
41
Explain the principle upon which vaccinations are based
- The initial concentration of antibodies to antigen A drops relatively quickly.
- The memory cells that are produced during this first infectious period ensure that, when the immune system is challenged a second time with the same antigen A, the reaction will be much faster to bring the infection under control.
42
What happens when the immune system if challenged a second time?
- The memory cells (formed during the primary response) divide by mitosis to form clones of plasma cells and memory cells.
- The former produce antibodies to give a fast response to the invading pathogen, while the memory cells stay in the body to defend against any future attack.
43
Which is faster: the primary or secondary response?
The secondary response
44
Why is the secondary response faster than the primary?
The fact that memory cells can directly give rise to plasma cells without the need for antigen presentation or activation of helper T cells and B cells, allows the secondary response to be much faster than the primary response.
45
Explain how vaccinations work
- Vaccinations inject a weakened form of the pathogen or a toxin that is produced by the pathogen, into the body.
- Vaccines contain antigens that trigger immunity but do not cause the disease.
46
Explain how the tetanus vaccine works
- For example, when you are vaccinated against tetanus, you get a dose of inactivated tetanus toxin.
- The inactivated toxin triggers a primary immune response, resulting in the production of antibodies and memory cells.
- When exposed to the tetanus bacterium and its toxins a second time (that is when you are actually infected by the tetanus bacterium), the memory cells can produce massive numbers of antibodies, thus ensuring the macrophages and other killer cells can dispose of the infection.
47
Colored electron micrograph of a macrophage engulfing bacteria.
48
Describe the use of vaccines to treat smallpox
- Vaccination is a highly effective way to battle disease or even eradicate diseases from the face of the Earth.
- Smallpox was the first human infectious disease to have been eradicated by vaccination.
- Smallpox was an infectious disease with a high mortality rate of around 35%.
- It can be caused by either of two viruses: Variola major and V. minor.
- The last naturally occurring case of smallpox was diagnosed on 26 October 1977.
49
Why was the vaccination campaign to eradicate smallpox successful?
- Because the virus can only survive in humans and be transmitted from human to human.
- Once no more humans could harbor the virus, there was no longer a natural reservoir from which the virus could spread.
- Consequently, the virus became 'extinct' in the wild.
50
Yearly vaccination for influenza viruses is necessary because ___
Rapid mutation in flu viruses alters the surface proteins in viral protein coat.
51
What do vaccines contain?
Antigens that trigger immunity but do not cause the disease.
52
What is zoonosis?
The transmission of a disease from animals to humans.
53
Describe the presence of zoonosis and give an example
- There is an increasing number of pathogens that can cross the species barrier.
- An infamous example is the Ebola virus, which causes hemorrhagic fever.
54
What are the symptoms of Ebola?
Fever, throat and muscle pain, headaches, vomiting, diarrhea, decreased functioning of the liver and kidneys, and internal bleeding.
55
What is the mortality rate for people with Ebola?
Ebola has a very high mortality rate of between 55% and 90%.
56
What animals does Ebola occur in?
It also occurs in monkeys and fruit bats and, at one stage during its evolution, and probably after intensive and prolonged contact with humans, the virus was able to become an infectious agent in humans as well.
57
Some pathogens are ___, while others, such as the Ebola virus, cross ___.
Species-specific
Species barriers
58
Map showing recent outbreaks of Ebola virus in Africa
59
Describe the avian flu virus (H5N1)
- Another notorious example of zoonosis is the avian flu virus (H5N1).
- In 1987, the first H5N1 virus outbreak occurred, and since then there has been an increasing number of H5N1 bird-to-human transmissions.
- The H5N1 virus can be fatal in humans.
60
Give examples of other cases of zoonosis besides Ebola and the avian flu virus
The list includes the bubonic plague, Lyme disease, West Nile encephalitis, and Ross river virus, to name just a few.
61
Why are some zoonotic events, such as the swine flu, particularly concerning?
Because they have the potential to become a pandemic.
62
What is epidemiology?
- The study of the distribution, patterns, and causes of diseases in a population.
- By studying the spread, patterns, and causes of diseases, predictions can be made and preventative measures are undertaken.
63
How do vaccination programs benefit epidemiology?
- Vaccination programs also benefit, because epidemiological studies can predict where outbreaks may occur and how best to contain them.
- Epidemiological data can also show the impact vaccination programs have had on the occurrence of a particular disease.
64
Analysing epidemiological data for the exam
You should be able to analyse epidemiological data related to vaccination programmes.
65
What is zoonosis?
The transmission of a disease from animals to humans.
66
What are many of the reactions that one sees in response to contact with an allergen caused by?
The release of histamine
67
What is an allergen?
- Any substance that can cause an allergic reaction is called an allergen.
- The body treats the allergen as foreign or dangerous and produces a strong immune response to a substance that is generally harmless to the body.
68
Diagram showing common allergens
69
How is histamine produced?
By basophils and mast cells (both are types of white blood cells) found in the connective tissues.
70
What is one of the functions of histamine?
- One of the functions of histamine is to dilate and increase the permeability of capillaries.
- This enables white blood cells, such as mast cells and some proteins, to invade the affected tissues and engage the allergens.
71
Diagram showing the immune response after an allergen has entered the body
72
Describe what happens once an allergen enters the body
- Once an allergen enters the body, a B cell, also called a B lymphocyte, comes into contact with the allergen.
- Plasma cells start producing an antibody that circulates in the blood and binds to mast cells.
- These antibodies attach to and activate the mast cells.
- This triggers the release of histamines, a process called degranulation, and other compounds.
73
What reactions does histamine lead to?
- Histamine can bind to membrane-bound histamine receptors and cause allergic symptoms.
- Depending on the tissue, it can cause itchiness, a runny nose, sneezing, or, in more serious cases, redness and swelling.
- Severe allergic reactions can lead to anaphylactic shock, an extreme and often life-threatening allergic reaction to an antigen to which the body has become hypersensitive, potentially leading to death.
74
Use of antihistamines to treat allergic reactions
- In a normal case of an allergic reaction, the use of an antihistamine is recommended.
- Antihistamines reduce the leakiness of the capillaries.
- In the case of a severe allergic reaction, hospitalization and direct injection with epinephrine may be needed.
75
What are antihistamines?
Drugs that inhibit the action of histamine in the body by blocking the receptors of histamine.
76
Antihistamine treatment reduces ___
Blood vessel dilation
77
Which cells release histamines in the body?
Mast cells and basophils release histamines in response to allergens.
78
What are the uses of monoclonal antibodies?
- Monoclonal antibodies have many uses in biomedical tests: diagnostic tests for Crohn's disease, certain types of cancer, and pregnancy tests.
- They are also used as therapeutic agents in rheumatoid arthritis, B cell leukaemia and non-Hodgkin's lymphoma.
79
Who discovered monoclonal antibodies?
Georges Köhler, César Milstein and Niels Kaj Jerne published this technique in 1975 and shared the Nobel Prize in Physiology or Medicine in 1984 for the discovery.
80
What are monoclonal antibodies?
- Monospecific antibodies (antibodies that target the same antigen), produced from one cloned plasma cell.
- They can recognize and bind to one specific region of the antigen (in this case, sometimes referred to as an epitope).
81
What is the epitope?
A short amino acid sequence on the antigen that the antibody is able to recognise.
82
What are polyclonal antibodies?
- Antibodies secreted by plasma cells themselves derived from different B cell lineages that have recognized different epitopes of one specific antigen.
- They are thus a mixture of antibodies with different affinities for the same antigen.
83
How is a hybridoma cell created?
Fusion of a tumour cell with an antibody-producing plasma cell creates a hybridoma cell.
84
What types of cells are monoclonal antibodies produced by?
Hybridoma cells
85
Diagram showing the production of monoclonal antibodies
86
Explain the production of monoclonal antibodies
- A mouse is injected with an antigen X for which a monoclonal antibody is needed.
- Once the mouse's spleen starts to produce polyclonal antibodies in its plasma B cells, the spleen is removed and is fused with myeloma cells (an immortalized, cancerous cell line; these myeloma cells have lost certain abilities, such as the ability to replicate their own DNA).
- Cells are cultured on a medium that is selective for fused (hybridoma) cells. Unfused myeloma cells cannot grow because they cannot replicate their DNA.
- The hybridoma cells can replicate their own DNA.
- Each hybridoma cell is then cultured separately and screened.
- Once it is confirmed that a certain hybridoma is producing the right antibody, it is cultured indefinitely and monoclonal antibodies are harvested from it.
87
___ are used to test for pregnancy
Monoclonal antibodies
88
Diagram showing the basic principle of the hCG pregnancy test
89
Give an overview of how pregnancy tests work
- Monoclonal antibodies can be used to test for pregnancy via the presence of human chorionic gonadotrophin (hCG) in urine
- hCG is a hormone produced by women during foetal development and thus its presence in urine is indicative of pregnancy
90
Explain how pregnancy tests work
- The test stick is dipped into the woman’s urine.
- The test stick contains anti-HCG antibodies with attached blue dye. If HCG is present, it will bind to the antibodies.
- Monoclonal antibodies are attached to the membrane within a window on the test stick. If HCG is present in the urine and bound to the anti-HCG antibodies, the HCG will also bind to the monoclonal antibodies as it travels up the stick.
- This complex also contains blue dye, which shows a blue line within the window. This blue line indicates the presence of HCG and therefore a positive result.
- The urine continues to move up the test stick. As it reaches the top, there is another line of monoclonal antibodies. These antibodies are a complementary shape to the anti-HCG.
- The anti-HCG is always present, so this line will always turn blue as a result of the blue dye. This line acts as a control and allows the user to check if the test is working. This line does not indicate whether the user is pregnant or not.
91
Monoclonal antibodies are produced by fusion between ___
Mouse spleen B cells and myeloma cells
92
In pregnancy tests, if hCG is present, two lines appear to identify that a pregnancy has occurred.
hCG present in the urine binds to anti-hCG.
What is also bound to anti-hCG?
Dye
The dye allows the lines on the pregnancy test to be seen. In a positive test, the dye will show two lines, one control line, and one test line. If only one line is shown the test is negative, only the control line can be seen.
93
Agglutination
Cellular pathogens become clumped for easier removal
94
Outline four modes of antibody action
- Agglutination – Antibodies cause the sticking together of pathogens by attaching to the antigens on the surface. These clumped masses of pathogens are then easily ingested and destroyed by phagocytes. The large agglutinated mass can be filtered by the lymphatic system and then phagocytized.
- Opsonization – Antibodies make pathogens recognizable by binding to them and linking them to phagocytes.
- Neutralization of toxins – Antibodies bind to toxins produced by pathogens in the blood plasma preventing them from affecting susceptible cells.
-Neutralisation of viruses and bacteria – Antibodies can bind to the surface of viruses, preventing them from entering host cells.
- Complement activation – The complement system is a collection of proteins that ultimately lead to the perforation of the membranes of pathogens. Antibodies bound to the surface of a pathogen activate a complement cascade which leads to the formation of a “membrane attack complex” that forms a pore in the membrane of the pathogen allowing water and ions to enter the cell, causing the cell to lyse.
