blood serum that contains specific antibodies against an infective organism or poisonous substance. Antiserums are produced in animals (e.g., horse, sheep, ox, rabbit) and man in response to infection, intoxication, or vaccination and may be used in another individual to confer immunity to a specific disease or to treat bites or stings of venomous animals. Antiserums from animals are most often used, but in persons allergic to animals, human antiserums have proved valuable. See also antibody; antitoxin; immunization; vaccine.