9. Immunity Flashcards
Difference between active and passive immunity
Passive immunity is when antibodies are received from an outside source while active immunity is when antibodies can be produced within the person
Explain active immunity
active immunity involved production of antibodies by a person in response to exposure to a particular antigen.
B memory cells and t cells are produced and react quickly if another encounter occurs with the same organism
Natural active immunity
Acquired when a person comes into contact with a particular pathogen for the first time and activates the immune system to produce antibodies and b and t memory cells specific to that pathogens antigens
Artificial active immunity
Results from vaccination. In this case the body is injected with either a disabled pathogen or its toxins
Vaccines definition
Vaccines are used to activate the immune system to produce antibodies against specific disease causing organisms without actually causing the disease
What is inside a vaccine?
VAccines are prepared using dead or attenuated pathogens so the antigens of the pathogen are still present thus triggering the immune response of the person injected with teh vaccine
What does attenuated mean?
Organisms that are treated but not killed during the preparation of a vaccine are said to be attenuated, their disease causing capability had been removed and they can no longer replicate in human cells.
Example of attenuating bacteria
A bacterium with a capsule causes disease
Remove capsule
Without its capsule the bacterium no longer causes disease but still acts as an antigen
Types of vaccines
Living attenuated pathogens
Killed bacteria or inactivated viruses
One or more subunits of a pathogen
Treated harmless bacterial toxins, toxoids
Which type of vaccine is strongest?
Killed or inactivated vaccines produce a weaker immune response compared to the response from using live attenuated vaccines and the immunity lasts for a shorter period.
Killed or inactivated vaccines have to be administered more than once.
Difference between primary and secondary antibody response
When a vaccine is first injected into a person the immune system shows a primary antibody response.
A second injection of vaccine produces a secondary antibody response
Herd immunity definition
Herd immunity is the indirect protection of populations from infection where that protection is created by the presence of immune individuals in the population and the protection is received by unvaccinated individuals
When is herd immunity effective?
When a high proportion of the population has immunity
Applies only to infectious diseases
Who does herd immunity protect?
The vulnerable, new born babies, elderly people and those with immunodeficiency diseases
Passive immunity
Antibodies produced in one person (or other organism) and introduced into another can react with antigens to provide immunity.
Advantage of passive immunity
Gives immediate protection to the person receiving the antibodies.
However the immunity is short lived as the person injected with the antibodies did not produce them therefore no memory cells were made
Natural passive immunity
Occurs when a developing fetus receives maternal antibodies across the placenta which provides it with important protection IgG
A baby also acquired antibodies through the mothers breast milk iGG igA
Artificial passive immunity
Occurs when a person is injected with antibodies
The antibodies are obtained from blood plasma collected from voluntary blood donors where the antibodies are extracted from the blood plasma
Or antibodies extracted from other organisms such as rabbits horses and rats
Production of antivenom
- Antivenene for a tiger snake bite can be produced by collecting antibodies from a rabbit injected with the antigen to this venom.
- Inject antigen specific to tiger snake venom into rabbit
- Rabbits B cells with specific antibody to venom antigen are activated. Many plasma cells produce and secrete large amounts of antibody into blood plasma.
- Remove blood plasma from rabbit.
- Antibodies extracted and purified from blood plasma.
- Inject antibodies into person bitten by tiger snake. Antibodies neutralise venom.
Autoimmune diseases
- Sometimes the ability of the immune system to recognise self material from non self material breaks down
- When this occurs the immune system reacts as if some of the body’s own cells are non self
- B cells produce antibodies and t cells attack and destroy self cells in the same way that they attack and destroy invading microorganisms
- Body produces autoantibodies which result in autoimmune disease
Why do autoimmune diseases occur?
Infection with a pathogen displaying antigens similar to antigen molecules on the surface of a type of body cell results in the production of antibodies and activation of T cells which ultimately lead to the destruction of the pathogens. However body cells displaying the antigen on the cell membrane will also be targeted and destroyed.
Other factors such as hormones genes and drugs could trigger it
Example of autoimmune diseases
Multiple sclerosis, type 1 diabetes. systemic lupus erthyematosus
Allergy definition
An allergy is present when the persons immune system reacts abnormally to substances in the environment that are harmless to most people
How does hypersensitivity occur
- B cell encounters the allergen and differentiates into plasma cells
- The plasma cell produces antibodies
3. The antibodies bind to specific receptors on the surface of the mast cells
4. The mast cell binds to the allergen when it encounters it again
5. The mast cell releases histamine and other chemicals which together cause the symptoms of allergic reaction
Immunodeficiency diseases
Immunodeficiency is a malfunction or deficiency in one or more components of the immune system.
Immune system fails to produce antibodies and the person lacks protection agaisnt pathogens
Severe combined immunodeficiency SCID
Inherited disease, immune system fails to mature after birth. No thymus gland so T cells cannot be produced.
Cancer
Cancer cells are normal cells that have undergone transformation, divide uncontrollably and possess tumour associated antigens that mark them as non self to the immune system. Can evade recognition by the immune system by shedding their associated antigens
Monoclonal antibodies
- Drugs that can be used in the treatment of cancers
- Specifically designed sets of antibodies with every antibody in the set binding to the same antigen
Difference between naked and conjugated antibodies
Naked monoclonal antibodies do not have any other molecules joined to them
- stop the growth of new blood vessels to cancer
- Signalling immune cells to attack cancers
- Blocking signals for cell division
COnjugated mca have additional groups attached
- Deliver anticancer drugs to cancer cells
- deliver radioisotopes to cancer cells
