Neutrophil

Neutrophil granulocytes, generally referred to as neutrophils, are the most abundant type of white blood cells in humans and form an essential part of the immune system. They form part of the polymorphonuclear cell family together with basophils and eosinophils.

Their name arrives from staining characteristics on hematoxylin and eosin histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink.

Neutrophils are normally found in the blood stream. However, during the beginning (acute) phase of inflammation, particularly as a result of bacterial infection, neutrophils migrate toward the site of inflammation, firstly through the blood vessels, then through interstitial tissue, following chemical signals (such as Interleukin-8, Interferon-gamma, and C5a) in a process called chemotaxis.

They are the predominant cells in pus, accounting for its whitish/yellowish appearance. Neutrophils react within an hour of tissue injury and are the hallmark of acute inflammation.