Bee Sting Allergy Might Actually Be Useful

This article was originally posted on RealClearScience.

The adaptive immune response is the branch of our immune system that most people are familiar with. It’s the reason vaccines work. When exposed to a molecule that triggers an immune reaction (known as an “antigen”), the body produces antibodies that specifically bind to that molecule, eventually leading to its destruction. The most common class of antibody produced is called immunoglobulin G (IgG).

Our bodies can also produce a less common type of antibody called immunoglobulin E (IgE). Notably, IgE helps fight off parasitic infections, but other than that, its role is largely unknown. In the developed world, parasites are no longer a major concern, so immunologists believe that IgE occupies its time by causing trouble, instead.

If you have allergies, blame IgE. For some reason, benign substances such as peanuts and cat hair can incite our immune system, which kicks out gobs of IgE. These antibodies then bind to an immune cell called a mast cell, triggering it to release a bunch of chemicals which produce all the symptoms we commonly associate with allergies — sneezing, coughing, itchiness and overall misery. In worst case scenarios, an out-of-control allergic response called anaphylatic shock occurs. This can be deadly.

Does IgE have any modern-day redemptive qualities? According to new research in the journal Immunity, the answer is yes.

Immunologists first primed mice with various doses of bee venom, but we will restrict our discussion to the 100- and 200-ug doses. (100 ug is roughly the amount of venom a bee carries around in its stinger.) These doses were sublethal for most of the mice, but a few unlucky ones didn’t make it past this stage. Of the ones that survived, the researchers nailed them again three weeks later with a massive, lethal dose of bee venom, i.e., four “stings” of 200 ug venom each. (See figure.)

Almost all of the mice that were originally primed with saline (white circles) dropped dead, as expected. But, more than 40% of mice that were primed with 100 ug venom (yellow triangles) and more than 80% of mice that were primed with 200 ug venom (green triangles) survived. Subsequent experiments demonstrated that IgE was responsible for protecting the mice.

If the authors are correct (and it appears that they are), this would alter our understanding of basic immunology. IgE should no longer be viewed as mostly a troublemaking leftover of our parasite-infested past, but as a useful tool in the arsenal for combating toxic substances. However, why some people develop horrible overreactions to bee stings and other antigens is still a mystery and will continue to be a subject for further investigation.

Source: Marichal et al., “A Beneficial Role for Immunoglobulin E in Host Defense against Honeybee Venom”, Immunity (2013).