Azurophilic granules

Azurophilic granules are a type of granule found in neutrophils, which are a type of white blood cell. They are named for their affinity for azure dyes, and are also known as primary granules.

Structure and Composition

Azurophilic granules are large, dense granules that are easily visible under a light microscope. They are composed of a variety of proteins, including myeloperoxidase, defensin, and elastase, among others. These proteins are stored in the granules until they are needed by the neutrophil to combat pathogens.

Function

The primary function of azurophilic granules is to aid in the destruction of pathogens. When a neutrophil encounters a pathogen, it engulfs the pathogen in a process known as phagocytosis. The azurophilic granules then fuse with the phagosome, releasing their contents and killing the pathogen. This process is known as degranulation.

In addition to their role in pathogen destruction, azurophilic granules also play a role in inflammation. The proteins contained within the granules can be released into the surrounding tissue, where they can stimulate an inflammatory response.

Clinical Significance

Abnormalities in azurophilic granules can lead to a variety of diseases. For example, a lack of myeloperoxidase, one of the proteins found in azurophilic granules, can lead to chronic granulomatous disease, a condition characterized by recurrent infections. Similarly, mutations in the gene for elastase can lead to cyclic neutropenia, a condition characterized by periodic decreases in the number of neutrophils.

See Also

• Neutrophil granulocyte
• Granule (cell biology)
• Phagocytosis
• Inflammation