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).
Theory of Histamine Excess. Histamine from dietary sources and. from the activity of intestinal micro-. organisms will normally be catabolized. before gaining access to circulation. If enzyme activity is reduced, histamine. will gain access to blood and augment. the level of plasma histamine from.