Histamine, which is stored mainly in mast cells and basophils, is a prominent contributor to
allergic disease. Elevations in plasma or tissue histamine levels have been noted during
anaphylaxis and experimental allergic responses of the skin, nose, and airways. Of the four
cardinal signs of asthma (bronchospasm, edema, inflammation, and mucus secretion),
histamine is capable of mediating the first two through its H 1 receptor and mucus secretion
through its H 2 receptor. Of the five cardinal signs of allergic rhinitis (pruritus, mucosal …