Peroxidase activity in neutrophilic granulocyte (peripheral blood, guinea pig)

Electron microscopy (peroxidase reaction with diaminobenzidin staining). The elongated nucleus (3) of this strongly ameboid phagocytic cell has several projections. These nuclear extensions are interconnected by thin heterochromatin strands. The cytoplasm exhibits moderate amounts of organelles, glycogen accumulations (4) and many granules of varying forms, sizes and densities. The primary granules (1) are large spherical to ellipsoid (lightmicroscopic) azurophilic granules and are very electron-dense due to the peroxidase reaction with diaminobenzidin. They contain myeloperoxidase as an antibacterial substance but also acid hydrolases as acid phosphatase, arylsulfatase, beta glucuronidase. The majority of smaller, peroxidase-negative and electron-grey granules are the specific or secondary granules (2). They contain substances like lysozyme, phagocytin to be secreted extracellularly involved in mobilization of inflammatory mediators and complement activation.