The eosinophil is characterized by specific cytoplasmic granules that con tain a series of cationic toxins able to kill many targets, including helminths, protozoa, bacteria, and other cells. In bronchial asthma, considerable evidence exists that the eosinophil releases granule proteins, especially the major basic protein (MBP), which in turn mediate tissue abnormalities. Among eosinophil-activating factors, IL-5 has been associated with hel minth infection and hypersensitivity diseases and would appear to be an attractive target for pharmacological intervention. INTRODUCTION Information about the eosinophil has rapidly expanded over the past several years. The discovery that the eosinophil is a likely mediator of bronchial asthma (1) has increased interest regarding the eosinophil in asthma and other respiratory diseases. The occurrence of the eosinophilia myalgia syndrome (EMS) as an epidemic related to the ingestion of tainted L-tryptophan has further stimulated awareness of the eosinophil (2). This heightened interest is manifested by a dramatic increase in publications dealing with the eosinophil: for example, before 1975, approximately 100 publications per year .could be identified from the National Library of Medicine data base under the search term eosinophil; in 1990 over 900 articles on eosinophils were published. In this review, we briefly present 85 0066-4219/93/0401-0085$02.00
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