Component 3A- Active And Passive Immunity

Question 1

What is active immunity?

Answer 1

Where the individual produces antibodies and may be:

• Natural if it follows natural infection
• Artificial when it follows vaccination e.g. against Rubella
• Protection is long-lasting due to the production of antigen-specific memory cells.

Question 2

What is passive immunity?

Answer 2

Where the individual receives antibodies produced by another individual and may be:

• Natural when antibodies are transferred to the foetus via the placenta, or to the baby in breast milk.
• Artificial when pre-synthesised antibody is injected into an individual e.g. tetanus antitoxin.
• Protection is short lived because the antibodies are recognised as non-self and are destroyed and no memory cells are produced.

Question 3

How does a vaccine work?

Answer 3

It is a weak or killed pathogen, or a toxin or antigen derived from it. It stimulates the immune system to produce an immune response against it (detects it as foreign and the immune system behaves as if it were a pathogen) but it does not cause infection.

Question 4

Why may the injection of antibodies be used to provide passive immunity

Answer 4

1) In an emergency to provide rapid protection against a pathogen and this allows time for a persons immune system to develop an active immune response
2) Used in people who do not develop a strong immune response to vaccination or who have a weakened immune system.