Specific granule

Specific granules are secretory vesicles found exclusively in cells of the immune system called granulocytes.

It is sometimes described as applying specifically to neutrophils,^[1] and sometimes the term is applied to other types of cells.^[2]

These granules store a mixture of cytotoxic molecules, including many enzymes and antimicrobial peptides, that are released by a process called degranulation following activation of the granulocyte by an immune stimulus.

Specific granules are also known as "secondary granules".^[3]

Contents

Examples of cytotoxic molecule stored by specific granules in different granulocytes include:

• Neutrophil: alkaline phosphatase, lactoferrin, lysozyme, NADPH oxidase
• Eosinophil: cathepsin, major basic protein
• Basophil: heparin, histamine (not directly cytotoxic)

Clinical significance

A specific granule deficiency can be associated with CEBPE.^[4]