Brent Cornell

Key Knowledge: The difference between natural and artificial immunity and active and passive strategies for acquiring immunity

Immunity can be described as either active or passive, depending on how it is acquired:

• Active immunity involves the production of antibodies by the body itself and the subsequent development of memory cells
• Passive immunity results from the acquisition of antibodies from another source and hence memory cells are not developed

Active versus Passive Immunity

Active immunity will result in long-term immunity but passive immunity will not (due to the presence or absence of memory cells) 

• Both active and passive immunity can be induced by either natural or artificial mechanisms

Types of Active Immunity

• Natural – Producing antibodies in response to exposure to a pathogenic infection (i.e. challenge and response)
• Artificial – Producing antibodies in response to the controlled exposure to an attenuated pathogen (i.e. vaccination) 

Types of Passive Immunity

• Natural – Receiving antibodies from another organism (e.g. to the newborn via the delivery of breast milk)
• Artificial – Receiving manufactured antibodies via external delivery (e.g blood transfusions of monoclonal antibodies)