While protein is one of life’s most basic entities, it can also be deadly. Proteins from venoms, germs, and viruses, for example, can sicken or kill us. Consequently, the immune system is designed to identify foreign proteins that find their way into the bloodstream and break them down into the individual amino acids from which they are built.

Normally, the immune system breaks down harmless proteins (those from pollens, molds, animal dander, stings, bug bites, etc.) with macrophage enzymes, which work so effectively that we rarely are aware of them. However, in many people, the immune system mistakenly identifies harmless foreign proteins as dangerous pathogens. It then reacts by the release of a chemical called histamine, which causes the inflammation, itching, sneezing, watery eyes, and other discomforts we refer to as allergic reactions.