Antisera are medical preparations containing antibodies, serving as a rapid treatment for certain conditions. They offer immediate, temporary protection against various threats but do not stimulate the body’s own long-term immunity, a key distinction from vaccines. Antisera provide a pre-made defense, acting quickly when the body lacks time to mount its own immune response.
Understanding Antisera
Antisera are composed of blood serum, which contains specific antibodies. Antibodies are Y-shaped proteins produced by the immune system, designed to recognize and neutralize foreign invaders or toxins. These specialized proteins bind to specific harmful substances, marking them for destruction or directly inactivating them. The antibodies found in antisera are derived from an animal or human that has been exposed to a particular antigen, such as a toxin or pathogen, and has developed an immune response.
The antibodies within antisera can be either monoclonal, originating from a single type of immune cell and targeting one specific site on an antigen, or polyclonal, a mixture of antibodies from various immune cells targeting multiple sites on an antigen. This collection of antibodies in the serum gives antisera their protective properties.
How Antisera Provide Protection
Antisera provide protection through passive immunity. Pre-formed antibodies are directly introduced into a recipient’s body, rather than the recipient’s own immune system producing them. Once administered, these antibodies immediately bind to and neutralize specific toxins or pathogens, offering rapid defense in emergency situations.
The protection offered by antisera is temporary because the recipient’s immune system is not activated to produce its own antibodies. Unlike active immunity, which is gained through vaccination or natural infection and leads to the body’s long-term memory of a pathogen, passive immunity does not result in lasting defense. The introduced antibodies are eventually broken down and eliminated from the body, typically over weeks to a few months.
Key Medical Uses of Antisera
Antisera play roles in emergency medicine, providing defense against certain conditions. One application is antivenom, used to treat bites and stings from venomous animals like snakes, spiders, and scorpions. Antivenom contains antibodies that neutralize venom toxins, preventing or reducing tissue damage and systemic effects.
Antisera are also used as antitoxins to treat diseases caused by bacterial toxins, including diphtheria, tetanus, and botulism. Here, the potent toxins produced by bacteria are the primary threat. Antitoxins directly bind to and inactivate these circulating toxins, preventing harm to the body’s cells and organs.
A further use is in rabies post-exposure prophylaxis. If a person is potentially exposed to the rabies virus, often through a bite from a suspected rabid animal, rabies antiserum is administered alongside the rabies vaccine. The antiserum provides immediate antibodies, offering rapid protection while the vaccine stimulates the recipient’s own immune system to develop long-term immunity. This dual approach addresses the long incubation period of rabies and the disease’s severity once symptoms appear.
Creating Antisera
Producing antisera involves hyperimmunizing an animal with a specific antigen. Animals like horses, sheep, goats, and rabbits are used for their ability to produce large quantities of antibodies. The animal is repeatedly exposed to the antigen, such as snake venom or a bacterial toxin, often in increasing doses, to stimulate a strong immune response and high antibody production.
Once the animal has produced a high level of specific antibodies, blood is drawn. The blood then undergoes a process to separate the serum, which contains the desired antibodies, from other blood components. This serum is purified through various steps to remove unwanted substances and concentrate the antibodies. Modern production processes involve rigorous purification and testing to ensure the safety and effectiveness of the antisera, minimizing the risk of adverse reactions in recipients.