title: Regulation of spontaneous eosinophil apoptosis-a neglected area of importance.
abstract: Asthma is characterized by the accumulation of eosinophils in the airways in most phenotypes. Eosinophils are inflammatory cells that require an external survival-prolonging stimulus such as granulocyte macrophage-colony-stimulating factor (GM-CSF), interleukin (IL)-5, or IL-3 for survival. In their absence, eosinophils are programmed to die by spontaneous apoptosis in a few days. Eosinophil apoptosis can be accelerated by Fas ligation or by pharmacological agents such as glucocorticoids. Evidence exists for the relevance of these survival-prolonging and pro-apoptotic agents in the regulation of eosinophilic inflammation in inflamed airways. Much less is known about the physiological significance and mechanisms of spontaneous eosinophil apoptosis even though it forms the basis of regulation of eosinophil longevity by pathophysiological factors and pharmacological agents. This review concentrates on discussing the mechanisms of spontaneous eosinophil apoptosis compared to those of glucocorticoid- and Fas-induced apoptosis. We aim to answer the question whether the external apoptotic stimuli only augment the ongoing pathway of spontaneous apoptosis or truly activate a specific pathway.
authors.affiliation: The Immunopharmacology Research Group, School of Medicine University of Tampere and Tampere University Hospital, Tampere, Finland.
authors.forename: Pinja
authors.initials: P
authors.lastname: Ilmarinen
authors.affiliation: The Immunopharmacology Research Group, School of Medicine University of Tampere and Tampere University Hospital, Tampere, Finland.
authors.forename: Eeva
authors.initials: E
authors.lastname: Moilanen
authors.affiliation: The Immunopharmacology Research Group, School of Medicine University of Tampere and Tampere University Hospital, Tampere, Finland. ; Department of Respiratory Medicine, Seinäjoki Central Hospital, Seinäjoki, Finland and University of Tampere, Tampere, Finland.
authors.forename: Hannu
authors.initials: H
authors.lastname: Kankaanranta
keywords: Fas; asthma; eosinophils; glucocorticoids; spontaneous apoptosis