The word "allergy" appeared in 1920 and derives from the adjective allergic which was first introduced. It derives from the German word 'allergisch' (1906), which itself comes from the Greek allos: 'other' and ergia: 'action, efficacy.' The term atopy was introduced in 1923 and comes from the Greek letter 'a' (prefix meaning without) and 'topos': 'place' (without a place), to designate manifestations of allergic disorders, which could not be classified in the disease categories known at that time.
From a historical perspective, allergy has been known since Antiquity and reported in many writings, both anecdotally among Kings and in ancient Chinese or Greek medicine treatises. For example, Maimonides, a Jewish philosopher in Cordoba and the personal physician of the sultan Saladin II, wrote the "Treatise on Asthma" in the 12th century. These works described a few allergic diseases and give advice, some of which continue to be currently applicable.
In 1902, Charles Richet and Paul Portier discovered the phenomenon of anaphylaxis based on experiments conducted in animals and consisting of repeated injections aimed at making them get used to poisons.
Clement Von Pirquet, a Viennese pediatrician, who created the term "allergisch" in 1906, after noticing that subjects who had previously been in contact with the bacillus that causes tuberculosis reacted differently than those who had not been, when an injection of the toxin from the microorganism was made. Furthermore, previously sensitized subjects presented with an inflammatory skin reaction at the injection site, 24 to 48 hours later. This late-onset reaction has become the basis for the BCG (Bacillus of Calmette and Guerin) vaccine.
In 1908, Schultz and Dale demonstrated the role of histamine in anaphylaxis, but it was only in 1942 that Chase and Landsteiner demonstrated the role of lymphocytes in delayed-onset hypersensitivity. Desensitization was discovered in 1911 by Noon and Freeman, and the term 'atopy' was coined in 1923 by Coca and Cooke.
In 1963, a classification of hypersensitive reactions was proposed by Gell and Coombs. It consists of 4 types, from the type I reaction (including anaphylactic shock) up to delayed-onset hypersensitivity, i.e. type IV reaction.
Blood component responsible for immediate-onset allergy was isolated in 1967 by Ishizaka and then by Johansson and Bennich, it involved an unknown immunoglobulin which was called IgE.
In 1980, leukotrienes were identified among the chemical mediators released by the basophils and mastocytes, by Samuelson, Bergstrom and Vane.
An in-depth understanding of the mechanisms underlying allergies has especially been observed over the last 20 years.
Allergy also means patients who suffer when they come in contact with a component of their environment. Most often they even develop a reaction to several allergens, and in such a case are multi-allergenic subjects.