Mast cells have granules that contain histamine, which acts as a vasodilator, increasing vascular permeability.
Blood platelets contain histamine and serotonin that are released when platelets adhere to collagen fibers.
Prostaglandins are derived from fatty acids and sustain inflammatory response.
Leukotrienes are synthesized from arachidonic acid and increase bronchial constriction, attract neutrophils, and increase vascular permeability.