1460 BASIC PROTEIN FROAf

Although the eosinophil has been recognized as a distinctive type of blood cell for over 100 yr, its specific functions not shared by neutrophils remain unknown (1). One approach to the elucidation of the particular functions of eosinophils is the isolation and analysis of the constituents of granules from this cell. However, studies of eosinophil granules have been hampered by the difficulties of obtaining adequate numbers of eosinophils for study and of securing intact granules. Vercauteren took advantage of the resistance of horse eosinophil granules to lysis and isolated granule preparations (2-3). His studies suggested the presence of arginine-rich proteins in granules. Archer and Hirsch purified rat and horse eosinophils and isolated granules from these cells (4). They showed that many of the same hydrolytic enzymes present in granules from rabbit polymorphonuclear leukocytes were also present in eosinophil granules. The eosinophil granules differed from neutrophil granules in their high content of peroxidase and the absence of lysozyme and phagocytin.