Читать книгу Immunology - Richard Coico - Страница 75

Activation of the kinins and the coagulation system also contributes to localized inflammatory responses. Once activated, the kinins have several important localized effects on cells and organ systems. Together with the locally released cytokines, they (1) act directly on local smooth muscle and cause muscle contraction; (2) act on axons to block nervous impulses, leading to distal muscle relaxation; and (3) act on vascular endothelial cells, causing them to contract and leading to increase in vascular permeability.

Kinins are very potent nerve stimulators and are the molecules most responsible for pain (and itching) associated with inflammation. They are rapidly inactivated after their activation by proteases, which are generated during these localized responses.

Following kinin‐induced damage to blood vessels, the coagulation pathway is activated. Plasma enzymes are activated in a cascading manner contributing to the inflammatory response by forming a physical barrier with platelets (clot or thrombus) that prevents microorganisms from entering the bloodstream. The simultaneous activation of kinins and the coagulation system during inflammatory responses thus produces inhospitable conditions for invading pathogens as well as new physical barriers to limit their ability to use the circulatory system to gain entry to distal tissues and organs.