Artificial passive immunity is given by injecting ready-made antibodies into a person. The person's own lymphocytes are not activated, so no plasma cells or memory cells are produced.The antibodies are collected from the blood of people or animals that already have high levels of them. For example, horses or sheep can be injected with small, safe doses of snake venom; they make antibodies, which are then extracted from their blood plasma and purified. Monoclonal antibodies can also be made in the laboratory.Examples of use:
• antivenom after a bite from a venomous snake
• tetanus immunoglobulin (antitoxin) for a deep, dirty wound in someone who is not vaccinated
• rabies immunoglobulin after a bite from an animal that may have rabies, given together with the rabies vaccine
• anti-D antibodies given to Rhesus-negative pregnant women, so they do not make their own antibodies against a Rhesus-positive baby's blood.Advantage: protection is immediate, which is vital when there is no time for an active response, such as when a toxin acts within hours.Disadvantages:
• it is short-lived: the antibodies are proteins that are gradually broken down, so protection lasts only weeks to months
• there is no memory, so the person is not protected against future exposure
• antibodies from animals are non-self proteins, so the person may produce an immune response or allergic reaction against them, especially if treated more than once.Artificial passive immunity is therefore used for emergency protection, not long-term prevention.
• antivenom after a bite from a venomous snake
• tetanus immunoglobulin (antitoxin) for a deep, dirty wound in someone who is not vaccinated
• rabies immunoglobulin after a bite from an animal that may have rabies, given together with the rabies vaccine
• anti-D antibodies given to Rhesus-negative pregnant women, so they do not make their own antibodies against a Rhesus-positive baby's blood.Advantage: protection is immediate, which is vital when there is no time for an active response, such as when a toxin acts within hours.Disadvantages:
• it is short-lived: the antibodies are proteins that are gradually broken down, so protection lasts only weeks to months
• there is no memory, so the person is not protected against future exposure
• antibodies from animals are non-self proteins, so the person may produce an immune response or allergic reaction against them, especially if treated more than once.Artificial passive immunity is therefore used for emergency protection, not long-term prevention.