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).
By Sally Robertson, BSc. Histamine is a biologically active substance that plays a key role in the bodyâs inflammatory reaction to injury caused by infection, physical damage or allergy. Histamine is widely distributed throughout the animal kingdom and is also present in insect venom, many plants and bacteria.he increased permeability of blood vessels allows immune cells and substances to migrate from the bloodstream, through the vessels and into the site where injury or infection has occurred. Leukocytes and blood plasma proteins can then begin the process of fighting infection and healing the tissue.