Neutrophils are granulocyte subtypes that circulate in the bloodstream. These leukocytes are very well represented in the blood, comprising 70% of white blood cells within mammals. They function in surveying the bloodstream for signs of infection, and in times of injury, are immediately recruited to the sites of trauma. Neutrophils are a hallmark of acute inflammation. Kits for human neutrophil isolation generally use magnetic bead technology for convenient separation of other cell populations.