Phenomenon by which during an inflammation or immune reaction, specialized leukocytes (eosinophilic granulocytes) adhere to and pass through the endothelium of the blood vessels and the underlying matrix.

The reaction passes through the following steps:

 1. Rolling (the flow of cells is slowed down by first making contacts to the endothelium via P-selectin, E-selectin, and L-selectin and their receptors)

 2. Adhesion (After activation of leukocyte integrins, firm contacts are established between them and endothelium molecules of the Ig superfamily - LFA-1, Mac-1, VLA-4 etc.

 3. Flattening of the cells and diapedesis (Adhering leukocytes crawl to an intercellular junction of the endothelium and then transmigrate to or even through the intercellular matrix. This is mediated by a homophilic interactions of PECAM and CD31.