UpToDate on eosinophils

This review describes the eosinophil journey through the various physiological and pathophysiological phases, from production, maturation, and activation by chemokines and cytokines [especially eotaxin, interleukin (IL)-5, IL-3, and granulocyte-macrophage colony-stimulating factor (GM-CSF)], to interaction with the innate and adaptive immune system and tissue homing. Excessive production and activation of eosinophils lead to the release of granule proteins, such as major basic protein, eosinophil cationic protein, eosinophil peroxidase, and others, resulting in inflammation, cell cytotoxicity, and oxidative stress. The pathogenesis, clinical features, diagnostic processes, and the latest therapeutic approaches to the resulting diseases—which affect the upper and lower airways, gastrointestinal tract, skin, myocardium, and may occur systemically—are discussed.