Antitoxin

A microorganism sometimes produces a substance which causes a disease (a toxin). Behring successfully produced immunity against tetanus by injecting small doses of blood serum from another animal suffering tetanus. This also worked for diphteria, a common and fatal children's disease.
 Emil Adolf von Behring Germany 1890 Antitoxin

A microorganism sometimes produces a substance which causes a disease (a toxin). Behring successfully produced immunity against tetanus by injecting small doses of blood serum from another animal suffering tetanus. This also worked for diphteria, a common and fatal children's disease.