bio-physics-wiki

The so called sentinel cells are located in our skin to detect invasions by e.g. microbes and viruses in terms of the innate immune response. Macrophages and dendritic cells as well as mast cells belong to the class of antigen representing sentinel cells. When invaders enter our tissue through a damaged epidermis (wound), the sentinel cells respond by releasing cytokines (there are about 50 different cytokines many of them are called Interleukins).

Cytokines cause cells in the blood vessle to produce adhesion molecules and leads to vasodilation (wideing of bood vessles). This allows extravasion of rolling leukocytes into the tissue.