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 .