It serves a protective role, in the sense that neutralizing and destroying toxins at the site of injury is an attempt to prevent their spread to other tissues. The vessel dilation brings more blood to the site of injury, to remove toxins and dead cells. The increased permeability allows the defensive white blood cells and clot-forming chemicals to enter the damaged area. This response is caused by the release of chemicals from damaged cells. Pg's magnify and prolong the pain associated with inflammation.
Kinins can also affect nerve endings and create pain.
They are also needed for the cells under attack, because their metabolism rapidly increases. During inflammation, toxic proteinaceous material is released which can foster disease unless it is removed. Neutrophils release proteolytic enzymes when they arrive at the scene, to solubilize this material and prevent infection. Topical solutions of proteolytic enzymes have been utilized to decrease inflammation and increase healing. Calcium helps transport essential minerals to the site of inflammation.