Ectoenzymes controlling leukocyte traffic

Ectoenzymes are a diverse group of membrane proteins that have their catalytic sites outside the plasma membrane. Many of them are found on leukocytes and endothelial cells, and they are multifunctional in nature. Collectively, different ectoenzymes can modulate each step of leukocyteendothelial contacts, as well as subsequent cell migration in tissues. Here, we review how ectoenzymes belonging to the oxidase, NAD-metabolizing enzyme, nucleotidase and peptidase/protease families regulate and fine-tune leukocyte trafficking, and how ectoenzymes have been targeted both in preclinical and clinical trials.