of, relating to, or of the nature of preference: preferential policies. 2. showing or giving preference: a preferential hiring system. 3. receiving or enjoying preference, as a country in trade relations; favored. Origin of preferential.
Histamine dilates post-capillary venules, activates the endothelium, and increases blood vessel permeability. This leads to local edema (swelling), warmth, redness, and the attraction of other inflammatory cells to the site of release. It also depolarizes nerve endings (leading to itching or pain).
Histamine is secreted by basophils and mast cells as part of a local immune response to the presence of invading bodies. The basophils and mast cells are found in nearby connective tissue.y Dr Ananya Mandal, MD. Histamine is an amine that is produced as part of a local immune response to cause inflammation.