Known as polymorphonuclear leukocytes originate from bone marrow stem cells.
Represent 60-70% of total circulating leukocytes.
The absolute number of circulating neutrophils measured in a routine blod test reflects a small number of he available pool of biologically active cells.
Approximately half of the biologic pool of neutrophils outside the marrow are circulating and the other half marginated to vascular endothelium (Athens JW).
A large reserve of mature neutrophils exist in the bone marow before exiting into the peripheral blood.
Circulating neutrohils comprise approximately 4.5% of mature bone marrow neutrophils, and 1.7% of total marrow granulocytes.
Minor reduction in peripheral blood neutrophil counts do not increase risk of infection (Haddy, TB, Crosby WH)
First cells recruited to sites of infection or injury which can occur minutes to hours after reaching maturation.
A primary defense against infections and foreign substances that invade the body’s physical barriers.
Recruited to inflamed tissue by endothelial adhesion molecules and chemoattractants.
The net accumulation of neutrophils at sites of inflammation is a function of recruitment and median neutrophil lifespan.
Neutrophil apoptosis, or programmed cell death, is vital in controlling the duration of the early inflammatory response, thus restricting damage to tissues by the neutrophils.
Hypoxia increases neutrophil survival suggesting that that process may impair resolution of neutrophilic inflammatory processes such as acute respiratory distress syndrome, bronchiolitis organizing pneumonia and respiratory syncytial virus infection.
After docking to the endothelial surface which is mediated by selectins and leukocyte integrins, leukocytes transmigrate through blood vessel wall by diapedesis.
Eliminates invading organisms by phagocytosis, generates reactive oxygen metabolites, releases proteolytic enzymes and microbicidal substances stored in intracellular granules of mature cells.
Involved in transfusion related acute lung injury by endothelial activation which synthesizes chemokines and increases surface expression of adhesion molecules that cause polymorphonuclear adhesion and release of microbicidal agents that damage the endothelium, cause capillary leak and lung damage.
Smoking stimulates leukocyte counts.