Specific Granules of Human Neutrophil Leucocytes

many tissues, but are not usually stored intracellularly in appreciable amounts. Polymorphonuclear neutrophil leucocytes are a notable exception. In these cells collagenase has been found in the granule fraction (Lazarus et al., 1968, 1972), and, like other granule components (Bainton et al., 1971), is presumably synthesized and packaged into granules during maturation. Two main types of granule have been identified morphologically and biochemically in human neutrophils (Bainton et al., 1971; Bretz & Baggiolini, 1974; Dewald et al., 1975). Azurophil granules contain a range of acid hydrolases found in lysosomes in other cells, lysozyme and neutral proteinases, such as elastase and cathepsin G. Specific granules contain