Discovery of the Diphtheria Antitoxin

In 1890 Emil von Behring and Kitasato Shibasaburo published work showing that the serum of an animal immunized against diphtheria toxin could protect or treat another animal, establishing the principle of antitoxin serum therapy. Early human trials in 1892 gave inconsistent results, and the treatment became reliably effective only after 1894, once the production and dosing of the antitoxin were standardized. Behring received the first Nobel Prize in Physiology or Medicine in 1901 for this work, though Kitasato, who carried out much of the underlying laboratory research, was not included in the award because the prize rules of the time restricted it to a single recipient.