Antibody formed in the body in reaction to a bacterial toxin, which it can neutralize. People who have recovered from bacterial diseases often develop specific antitoxins that give them immunity against recurrence. Injecting an animal (usually a horse) with increasing doses of toxin produces a high concentration of antitoxin in the blood. The resulting highly concentrated preparation of antitoxins is called an antiserum. The first antitoxin developed (1890) was specific to diphtheria; today, antitoxins are also used to treat botulism, dysentery, gas gangrene, and tetanus.
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