Work

Our immune system protects us from attacks by microorganisms and poisonous substances. After experiencing an attack, the immune system learns to defend itself against new attacks—we become immune. One of the ways this is used is with vaccinations, when a low dosage of an infectious substance provides immunity. Through studies involving dogs, Charles Richet demonstrated an opposite effect in 1902. After an initial low dose of a substance, a new dose some weeks later could produce a severe reaction. He called the phenomenon anaphylaxis. The result had important implications for our understanding of allergies.