Britannica
Sources used in this answer
How does histamine affect blood vessels during inflammation?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
inflammation
The main function of complement proteins is to aid in the destruction of pathogens by piercing their outer membranes (cell lysis) or by making them more attractive to phagocytic cells such as macrophages (a process known as opsonization). Some complement components also promote inflammation by stimulating cells to release histamine and by attracting phagocytic cells to the site of infection.
During the inflammatory response, histamine acts as a critical chemical mediator released primarily from the granules of mast cells and basophils in response to tissue injury or infection.12
Its primary effects on blood vessels include:
- Vasodilation: Histamine triggers the dilation of blood vessels, which increases local blood flow to the site of injury.12
- Increased Permeability: It increases the permeability of vessel walls, allowing plasma proteins and immune system cellsāsuch as leukocytesāto leak out of the bloodstream.12
This process is essential for the body's defense, as it enables immune cells to migrate directly to the site of damage or infection to begin the healing process and fight pathogens.1