Histamine is a protein produced by <u>mast cells</u> in the body. It plays a very important role in the immune system of the body. Histamine is released in the body when <u>affected by an allergen</u>, e.g, pollen or animal dander. The immune system of the body will respond to such allergen by <u>making more mucus in the nose by releasing histamine</u>. There will be sneezing, itching, coughing and runny nose in response. This is a <u>basic defense of the body's immune system</u> to not enter any particle inside the body.
