Why the overlap in peanut and tree nut allergies?
So from this - http://content.karger.com/produktedb/produkte.asp?typ=pdf&amp;file=IAA2003131004234 - it sounds like they both share IgE-reactive (http://en.wikipedia.org/wiki/Immunoglobulin_E) epitopes.


  Both native and recombinant nut allergens have been identified and characterized and, for some, the IgE-reactive epitopes described. Some allergens, such as lipid transfer proteins, profilins, and members of the Bet v 1-related family, represent minor constituents in tree nuts. These allergens are frequently cross-reactive with other food and pollen homologues, and are considered panallergens. Others, such as legumins, vicilins, and 2S albumins, represent major seed storage protein constituents of the nuts.