The present invention encompasses the surprising finding that nanoparticle compositions can have beneficial effects on allergy even when prepared without a known specific allergy therapeutic. The present invention provides such nanoparticle compositions. In some embodiments, provided nanoparticles are associated with functional elements that cause the nanoparticles to mimic bacterial cells. The present invention encompasses the surprising finding that provided nanoparticles may be useful for treatment and/or prevention of multiple different allergies in a single patient. The present invention encompasses the recognition that provided empty nanoparticles may be useful as a “pan-allergy” therapeutic and/or vaccine.