An azurophilic granule is a cellular object readily stainable with a Romanowsky stain. In

white blood cell White blood cells, also called leukocytes or leucocytes, are the cell (biology), cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and de ...

s and hyperchromatin, staining imparts a

burgundy Burgundy (; french: link=no, Bourgogne ) is a historical territory and former administrative region and province of east-central France. The province was once home to the Dukes of Burgundy from the early 11th until the late 15th century. The c ...

merlot Merlot is a dark blue–colored wine grape variety, that is used as both a blending grape and for varietal wines. The name ''Merlot'' is thought to be a diminutive of ''merle'', the French name for the blackbird, probably a reference to the ...

coloration. Neutrophils in particular are known for containing azurophils loaded with a wide variety of anti-microbial

defensin Defensins are small cysteine-rich cationic proteins across cellular life, including vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, ...

s that fuse with phagocytic vacuoles. Azurophils may contain myeloperoxidase,

phospholipase A2 The enzyme phospholipase A2 (EC 3.1.1.4, PLA2, systematic name phosphatidylcholine 2-acylhydrolase) catalyse the cleavage of fatty acids in position 2 of phospholipids, hydrolyzing the bond between the second fatty acid “tail” and the glyce ...

, acid hydrolases, elastase, defensins, neutral serine proteases, bactericidal/permeability-increasing protein, lysozyme, cathepsin G, proteinase 3, and

proteoglycan Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to whic ...

s. Azurophil granules are also known as "primary granules". Furthermore, the term "azurophils" may refer to a unique type of cells, identified only in

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s. These cells are similar in size to so-called heterophils with abundant cytoplasm that is finely to coarsely granular and may sometimes contain vacuoles. Granules may impart a purplish hue to the cytoplasm, particularly to the outer region. Occasionally, azurophils are observed with vacuolated cytoplasm.

References

Hematology Staining {{hematology-stub

See also

References