[The role of eosinophils in inflammatory reactions]

Recent findings have contributed substantially to a better understanding of the ontogeny and function of eosinophil leukocytes. Together with other granulocytes, the cells originate in the bone marrow from a common stem cell. Their development is regulated by genetic factors and by products of T-lymphocytes. Chemotactic factors of the complement cascade (C5a), lymphokines and eosinophil chemotactic leukotrienes (ECL) stimulate their migration to tissue sites. Generation and biological effectiveness of eosinophil chemotactic factors can be modulated in numerous ways, thus changing the outcome of the inflammatory event. The probably most important effector function of eosinophils is their cytotoxicity which plays a role in the killing of parasites. Markedly elevated numbers of eosinophils can, however, cause auto-aggression against the body's own cells, such as the Purkinje cells of the brain, cardiac muscle cells or epithelial cells of the skin and the bronchial tree. Eosinophils are therefore cells capable of both serving and damaging the human host.