Sneeze Sleuths: Uncovering Allergies' Secrets

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Allergy sufferers know the symptoms all too well: itchy eyes, stuffy nose, wheezing, and in the most severe cases, such difficulty in breathing that it could lead to death.

But just why do some substances cause allergic reactions? Though 50 million Americans endure allergies, it isn't well-understood why certain agents spark an immune response—that's what all the wheezing and itching is about—in those people and not in others.

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