[Advance in the method of eosinophil separation--separation of human eosinophils in density gradients and measurement of density distribution].

To separate human eosinophils from peripheral blood, we used six discontinuous density gradients of Percoll solution (1.070, 1.080, 1.085, 1.090, 1.095 and 1.100 g/ml). Eosinophils isolated from patients with bronchial asthma or hypereosinophilic syndrome (HES) were shifted to the lighter density as compared with that from healthy subjects. Light-shift of density of eosinophils (hypodense eosinophils) was mimicked by several agents including chemical mediators such as histamine or platelet-activating factor (PAF), cytokines such as interleukin (IL)-3, IL-5 or GM-CSF. It has been reported that hypodense eosinophils survive, and the ability to generate leukotriene C4, superoxide anion or to secrete tissue injurious protein such as ECP or MBP augments as compared with that of normal density (normodense eosinophils). This separation method of eosinophils using a Percoll solution may contribute to accurate understanding a role of eosinophils in the pathogenesis of bronchial asthma or HES.