Passive immunity can be defined as the transfer of active humoral immunity of ready-made antibodies. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and it can also be induced artificially, when high levels of antibodies specific to a pathogen or toxin (obtained from humans, horses, or other animals) are transferred to non-immune persons through blood products that contain antibodies, such as in immunoglobulin therapy or antiserum therapy. wikipedia
Passive immunity doesn’t require the body to make antibodies to antigens.
The antibodies are introduced from outside the organism.
Examples of Passive Immunity
An example of natural passive immunity is a baby’s protection against certain infections by getting antibodies through colostrum or breast milk. An example of artificial passive immunity is getting an injection of antisera, which is a suspension of antibody particles. Another example is the injection of snake antivenom following a bite.
Characteristics of Passive Immunity
- Passive immunity is conferred from outside the body, so it doesn’t require exposure to an infectious agent or its antigen.
- There is no delay for the action of passive immunity. Its response to an infectious agent is immediate.
- Passive immunity is not as long-lasting as active immunity. It’s typically only effective for a few days.
- A condition called serum sickness can result from exposure to antisera.