Life-threatening antibodies: The discovery of anaphylaxis.

It was at the turn of the 20th century, that immune serum was found both to save children dying from toxins of deadly pathogens, and to kill a dog within minutes following an injection of harmless doses of sea anemone toxins. This means that, before being formally identified in immune serum, antibodies were already known to be both protective and pathogenic. For this provocative finding, Charles Richet was awarded the 1913 Nobel Prize in Physiology or Medicine. Because, as its name said, anaphylaxis was understood as "the contrary of protection," unique mechanisms were found to explain it. Because, as its name did not initially say but finally said, allergy was understood as a reaction "other" than immunity, its symptoms were explained by mechanisms similar to those that explained anaphylaxis. We examined here the intricate relationships between anaphylaxis, allergy and immunity. Progressively anaphylaxis became one among other pathological effects of an immune response, and allergy an inflammatory disease among others. Looking at antibodies back in the past enables us not only to learn where they come from, but also to follow trends that contributed to shape immunology, some of which may persist in today's immunological thinking and say something about the future.