Eosinophils: multifunctional and distinctive properties.

The eosinophil is a granulocyte prominent in allergic diseases and inflammatory responses against helminthic parasites. The eosinophil was named by Paul Ehrlich in 1879, and derives from the intense staining of its granules with the acidic dye eosin. It has been the subject of extensive investigation ever since. It is strongly associated with human diseases involving mucosal surfaces, such as allergic asthma, atopic dermatitis and gastrointestinal disorders. Eosinophils are likely involved in tissue homeostasis, modulation of adaptive immune responses, innate immunity to certain microbes and pathological changes in allergic disorders. Thus, the eosinophil is considered a multifunctional leukocyte that contributes to a wide variety of physiological and pathological processes, depending on its location and activation status. Further studies will be necessary to better understand the biology of this extraordinary leukocyte and to reveal the importance of the cell in human health and disease.