FURTHER CHARACTERIZATION OF THE GELATINASE-CONTAINING PARTICLES OF HUMAN NEUTROPHILS

In addition to azurophil and specific granules, a third storage compar tment is known to exist in the neutrophils. This compartment which con sists of morphologically heterogeneous particles is characterized by a high specific activity in gelatinase. A gelatinase enriched fraction was prepared by subcellular fractionation of neutrophil homogenates us ing rate zonal centrifugation. This fraction was enriched in diamine o xidase. Among the proteins released from the neutrophils upon stimulat ion by formyl peptides, those belonging to the gelatinase enriched fra ction were determined after removal of the proteins from specific and azurophil granules by selective immunoadsorption. Gelatinase was recov ered together with tetranectin, beta(2)-microglobulin and diamine oxid ase in the same fraction. Differences in the kinetics of release of ge latinase and diamine oxidase versus vitamine B-12-binding protein sugg est that the proteins belong to distinct subcellular structures.