While a bee sting causes only temporary pain and discomfort for most people, for those with a bee venom allergy, the consequences can be devastating and sometimes fatal, as anaphylactic shock brings a drop in blood pressure, itchy hives and breathing problems.
Now researchers at Stanford University report those severe allergic reactions may have an evolutionary explanation, centered on a process known as innate immune responses.
When exposed to a foreign substance such as a pathogen or a toxic material like venom for the first time, immune cells called mast cells, which reside in most of the body's tissues, are poised to unleash signals that turn on defense responses when a pathogen or toxin intrudes.
In allergic reactions, a type of antibody called IgE binds to the surface of mast cells and prompts them to initiate an adaptive immune response.
It had been believed IgE might be required for protection against a lethal sting, and that allergies are an extreme, and maladaptive, example of this type of defense.
"Our findings support the hypothesis that this kind of venom-specific, IgE-associated, adaptive immune response developed, at least in evolutionary terms, to protect the host against potentially toxic amounts of venom, such as would happen if the animal encountered a whole nest of bees, or in the event of a snakebite," researcher Stephen Galli said.
"Anaphylaxis probably represents the extreme end of a spectrum of IgE-associated reactivity, which in some unfortunate individuals is either poorly regulated or excessively robust, so the reaction itself can become dangerous to them."
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