Neutrophils are the most frequently occurring white blood cell. They possess 3-5 nuclear lobes and characteristic purple cytoplasmic staining with Romanowsky stains.
They have a key role in the local defence to injury during inflammation by ingesting and killing bacteria. They can also have systemic effects by releasing endogenous pyrogen to cause fever.
Alike the other granulocytes, basophils and eosinophils, they arise from the promyelocyte precursor cell within bone marrow. There are three populations of neutrophils:
Once released from bone marrow, typically after about 2 weeks, neutrophils spend about a day in the circulation and 2-3 days in extravascular compartments.
At times of need, the post-mitotic and marginating pools can be mobilised to increase the number of circulating neutrophils. Mobilisation of the post-mitotic pool may lead to band cell appearance - the left shift.
Last reviewed 01/2018