Antibody production and vaccination

Question 1

How does the immune system recognise cells as ‘self’ and ‘non-self’?

Answer 1

• Cells of an organism have unique molecules on the cell surface which act as markers to identify them
• These markers are macro-molecules, allow immune system to distinguish cells between ‘self’ and ‘non-self’

Question 2

What happens when the markers identify the microorganism as non-self?

Answer 2

• All microorganisms (both pathogenic and non-pathogenic) trigger an immune response
• Antigens are the molecules that can trigger an immune response, meaning antibodies are produced

Question 3

Where are antigens found?

Answer 3

• Found on cell surface membranes of pathogen
• Some glycolipids or glycoproteins on the surface can act as antigens

Question 4

How does the body stimulate an allergic reaction?

Answer 4

• Allergies result from an immune response that is triggered by antigen on the surface of an allergen

Question 5

What substances can be recognised as non-self?

Answer 5

• Viruses, foreign substances (vaccines), pollen, parasite, fungi, bacteria, transplant

Question 6

What do red blood cells have that make them unique?

Answer 6

• RBC have specific markers (antigens) on their surface which determine the blood group
• If a transfusion is given to an individual with mismatched blood group, the antigen on the RBC will trigger an immune response

Question 7

What are the two antigen markers?

Answer 7

• The ABO marker determines whether an individual is blood group A, B, AB or O
• The Rhesus (Rh) marker determines whether an individual is rhesus positive or negative

Question 8

What makes blood type A and type B unique?

Answer 8

• Type A has a type A antigen, which is added to the initial ‘H’ antigen
• Type B has a type B antigen, which is added to the initial ‘H’ antigen

Question 9

What type of antigens does blood type AB have?

Answer 9

• Has type A and B antigens, consists of two ‘H’ antigens.
• The H antigen can be modified by other molecules

Question 10

What makes blood type O unique?

Answer 10

• The ‘H’ marker is not modified, which means there are neither A nor B antigens

Question 11

What does it mean for a blood type to be rhesus positive or negative?

Answer 11

• O+, B+, A+, AB+
• Is determined by the presence of the rhesus D (RhD) antigen
• Most are positive

Question 12

What happens when one receives the wrong blood group?

Answer 12

• An immune response will occur due to the presence of antibodies in the recipient’s blood that bind to blood cells with non-self antigens
• This leads to agglutination (clumping) in blood vessels (could be fatal)
• Agglutination occurs when RBC clump together due to binding of antigens and antibodies

Question 13

What blood types can received which donations?

Answer 13

• O- can donate to all others but can only received from O-
• AB+ can receive from all blood types but can only donate to AB+ blood types

Question 14

What is a pathogen? What are diseases?

Answer 14

• An agent that causes diseases
• Disease: a condition that disturbs the normal functioning of the body

Question 15

What is pathogenesis? When does this occur?

Answer 15

• When pathogens are species specific, their ability to cause disease is limited to a particular species
• This may happen when a species does not have necessary receptors
• The body temperature may not reach a temp. that is required for development of the diease

Question 16

Can certain pathogens be non-specific?

Answer 16

• Some can cross the species barrier and be able to infect and cause disease in a range of hosts

Question 17

What is Zoonosis? Give examples.

Answer 17

• Zoonotic diseases are those which can cross the species barrier from animal to human
• E.g. rabies, Polio, tuberculosis, HIV
• Difficult to control due to the close relationship between animals and humans

Question 18

What happens in a specific immune response?

Answer 18

• Occurs when a foreign pathogen enters body
• T-Helper cells and B cells (types of lymphocytes) respond to the antigens since they have specific receptors on their membrane
• Receptors are similar to antibodies (specific to one antigen)
• A phagocyte engulfs the pathogen and detects it as non-self based on the antigens
• T-helper cells (with complementary receptor proteins to the antigen) will bind to the antigen and become activated by the phagocyte
• The now activated T-helper cell binds with complementary receptors of a B-lymphocyte
• On binding, the T-helper cells releases signalling proteins and activate these B-cells

Question 19

What are plasma cells and how are they produced in a specific immune response?

Answer 19

• In the immune response, activated B-cells mature to form two types of cells, plasma cells and memory cells
• Plasma cells produce a large volume of antibodies that are specific to the antigen that triggered the immune response
• Plasma cells contain a lot of RER which promote protein synthesis to make antibodies (short-lived)

Question 20

What is clonal selection?

Answer 20

• Identifying and activating a B-cell with the complementary receptor of the target antigen
• This causes clonal expansion, the activated B-cell divides by mitosis to create clones of itself
• B-cells can produce antibodies, which means the clones will produce the same antibody that is complementary to the antigen

Question 21

What happens to the clones of the B-cells?

Answer 21

• Some differentiate into plasma cells
• The others become memory cells that remain in the blood and form a basis of immunological memory

Question 22

What is the difference between a primary and secondary immune response?

Answer 22

• Primary: slow response and occurs when system encounters a new antigen
• Takes time to identify the complementary antibody for the antigen
• Secondary: faster response and occurs when system already encountered antigen
• The memory cell has information for antibody production, must faster replication
• Symptoms do not develop, pathogen destroyed before significant damage is done
  Check book

Question 23

What are the functions of antibodies?

Answer 23

• Destroy pathogens within the body
• They help in the destruction in 6 different ways

Question 24

How do antibodies help in the destruction of pathogens through agglutination and opsonisation?

Answer 24

• Agglutination: Cause pathogens carrying antigen-antibody complexes to clump together
• Reduces chances that pathogens spread, instead removed by lymphatic system and digested by phagocytes
• Opsonisation: coating of a pathogen with antibodies to promote and enhance phagocytosis.

Question 25

How do antibodies help in the destruction of pathogens through neutralisation and activity reduction?

Answer 25

• Neutralisation: antibodies combine with viruses and bacteria to block them from entering or damaging cells
• Activity reduction: antibodies can attach to the flagella of bacteria making them less active (easier to carry out phagocytosis)

Question 26

How do antibodies help in the destruction of pathogens through neutralisation of toxins and complement activation?

Answer 26

• Neutralisation of toxins: antibodies act as anti-toxins by binding to toxins, makes them harmless
• Complement activation: Antibodies trigger complement proteins which create holes in the cell walls of pathogen, causes them to burst during osmosis

Question 27

How is immunity initiated?

Answer 27

• When a specific antigen is exposed, which causes the production of the complementary antibody and memory cells
• First exposure: primary immune response, leads to immunity when memory cells and antibodies remain in blood after pathogen gone
• Secondary exposure: antigen found repeatedly, memory cells recognise antigen and divide quickly into plasma cells
• Infection destroyed faster and pathogen removed before symptoms develop

Question 28

How do vaccines promote immunity?

Answer 28

• Vaccine contains antigens, injecting them causes a specific immune response where antibodies are released by plasma cells
• Antigens trigger immunity but do not cause the disease
• Induces long-term immunity, stimulates production of memory cells
• Memory cells recognise the antigen when re-encountered and produces antibodies, faster, stronger secondary response

Question 29

What are the two different types of vaccines?

Answer 29

• Live attenuated: weakened version of the pathogen
• Inactivated: killed, non-living components of pathogens (or just antigens alone)
• Vaccines trigger the primary immune response

Question 30

What is herd immunity?

Answer 30

• Method to protect populations from diseases
• Occurs when a sufficiently large proportion of the population has been vaccination (immune), difficult for pathogen to spread
• Those not immunised are protected, unlikely to contract disease

Question 31

How were Smallpox eradicated with herd immunity?

Answer 31

• WHO aim to eradicate the disease in 1967
• Vaccinate 80% of population, quarantine for those infected and living nearby

Question 32

What were the reasons why smallpox could be eradicated?

Answer 32

• Easily identifiable symptoms
• Transmission occured via direct contact, only affected humans
• Infection period short lived, 3-4 weeks
• Virus was stable, did not mutate, same vaccine used world-wide
• Immunity was long-term, global cooperation

Question 33

What factors must be remembered when analysing trends of data?

Answer 33

• Population increases, increased risk of potential outbreaks
• Improvement of health care services, public sanitation
• Different regions, climate, different levels of exposure
• Epidemiological data can show the impact vaccination programmes have on the occurrence of a particular disease

Question 34

What are histamines and how are the produced?

Answer 34

• Chemicals produced by white blood cells in response to allergens
• Allergens are antigens and hence encountered by B-cells
• B-cells produce IgE antibodies, they attach to mast cells or basophils
• This stimulates histamine production, dilates blood vessels, more blood flow, leads to inflammation (allergic reaction)
• Triggers specific and non-specific responses

Question 35

What effect does histamines have?

Answer 35

• They bind to receptors in body cells that cause allergic reactions
• Reactions may include: itchy skin, runny nose, sneezing, rashes, swelling
• To relieve the symptoms, antihistamines are taken that bind to histamine receptors (act as inhibitor)

Question 36

What are Monoclonal antibodies (Mabs)?

Answer 36

• Artificially produced antibodies produced from a single B cell clone
• The hybridoma method is used to make monoclonal antibodies

Question 37

How are monoclonal antibodies produced?

Answer 37

• Animal injected with an antigen and in response produces antigen-specific plasma cells (mouse spleen B cells)
• The plasma cells are fused with tumor cells (myeloma cells) capable of endless divisions
• The fusion results in hybridoma cells, they are capable of synthesising large quantities of monoclonal antibodies (clones)
• These antibodies will then bind to antigens

Question 38

For what are monoclonal antibodies used?

Answer 38

• Therapeutic reasons: diagnosis of HIV, malaria, Covid-19, food testing
• Can be used to target cancer cells that the body fails to recognise as harmful
• Testing for pregnancy testing

Question 39

How are monoclonal antibodies used in pregnancy test kits?

Answer 39

• Taking a urine sample, the sticks itself contain monoclonal antibody molecules
• These antibodies are specific to a hormone produced during pregnancy (hCG)
• Antibodies in the testing sticks all originate from a single B-cell that produce the same antibody specific to hCG

Question 40

Macrophages are types of white blood cells which are phagocytes.