Richet, Charles Robert (1850-1935)

French physiologist who was awarded a Nobel Prize for Physiology or Medicine in 1913 for his work on allergic responses. He discovered chemical hypersensitiveness, or anaphylaxis.

Richet discovered in 1902 that certain chemicals produced hypersensitivity when injected into dogs. Richet and colleagues determined the smallest lethal dose of Portuguese man-of-war extract able to kill a dog in two or three days. They then injected other dogs with a smaller dose, which caused transient symptoms. When these dogs were reinjected with a similar dose after an interval of several weeks, a violent reaction occurred which resulted in death.

The first dose had sensitized the animal to the second dose; a phenomenon he called anaphylaxis. Richet extended these studies by making healthy animals anaphylactic by injecting them with sera from dogs already with the condition, thereby indicating that substances from the blood were involved in anaphylaxis.

Richet was born and educated in Paris, graduating in medicine from the University of Paris in 1877 and later becoming professor of physiology in Paris.