There has been a fascinating study on peanut allergies published in Science Translational Magazine this month, and it could have huge significance towards our understanding of how we develop allergies in the first place. But in order to understand all that good stuff, here’s what you’ll need to know about antibodies:
Antibodies are molecules produced by a type of white blood cells known as B cells.
All B cells are the same at first, and share the same basic DNA (“germline sequences”, if you’re feeling fancy). When B cells begin to mature, that B cell’s DNA rearranges itself. Because of that rearrangement of DNA, the antibodies that B cell (and its “kids”) produces will be completely unique to the antibodies other B cells produce. That antibody will randomly have an affinity to a very, very specific random particle, called an antigen. B cells aren’t big believers in being a “Jack of All Trades”.
When that antigen is a viral particle, everything is just dandy. The immune system is working as intended.
When that antigen is a particle found in peanuts…then you have a problem.
Which brings us to the study in question.
The researchers looked into different antibodies that all reacted to the same common peanut antigen. Despite having completely random DNA rearrangements, the B cells all came to the same conclusion: “PEANUTS MUST DIE!!!!”. And now their respective humans need to carry an Epi-Pen for the rest of their lives.
So, our researchers, Marini-Rapaport et al, asked the obvious question: what the HECK is going on with those DNA rearrangements to make peanut allergies so danged common?
First, they identified exactly what parts of the antigen the antibodies all interacted with. They found that the DNA that codes for those interactions was found in base DNA, pre-rearrangement. That makes it more likely that, when recombination occurs, the peanut-binding portion remains.
In other words, peanut allergy isn’t just a purely random thing: our deck is metaphorically stacked against peanuts for some unknown reason! For all we know, ancient peanuts could have had a heck of a kick, for human evolution to see it and go “yeah, I’d rather die than eat THAT again”.