Extravasation

Note that this process happens for monocytes as well.

Dilation of capillaries
Inflammatory mediators trigger changes in blood vessel walls (endothelium) → vasodilation and expression of adhesion molecules.

Rolling
Neutrophil sialyl-Lewisx carbohydrate (s-Lex) reversibly binds to selectins (P-selectin, E-selectin) on activated endothelium. Neutrophil/monocyte slows down.

Arrest and adhesion
In response to chemokine CXCL8, neutrophil integrins (LFA-1, CR3) undergo conformational changes. Increased affinity for endothelial '''ICAM-1. '''Tight binding stops rolling.

Diapedesis
Neutrophil squeezes between endothelial cells and secretes proteases to degrade the basement membrane.

Migration
Mediated by a chemokine gradient (CXCL8), neutrophils with IL-8 receptors travel towards highest IL-8 concentration until they reach the infection site.