Also known as polymorphonuclear leukocytes, are derived from the bone marrow and circulate freely in the blood
- Formed from CFU-GM progenitor cells and each day 1014 cells released into the circulation
- Most abundant WBC and form basis of acute inflammatory responses.
- Action is to kill microorganisms
- Live for 6-10 hours and removed by the spleen
- Along the sides of blood vessels besides the endothelium known as the "marginating pool"
- Within the main circulation. These groups are equal
- Adrenaline or stress moves neutrophils from marginating pool to the main circulation
- Contain primary and secondary and even tertiary granules
- Primary granules - myeloperoxidase
- Secondary granules - membrane proteins and adhesion molecules and contain enzyme NADPH oxidase, which produces large quantities of superoxide, a reactive oxygen species for killing engulfed organisms
- Tertiary granules
- They are highly motile through the actions of an intracellular cytoskeleton
- Cytoskeleton enables them to move towards sites of inflammation.
- Found in marginating pool found close to the vascular endothelium
- From here neutrophils can attach to the endothelium using adhesion molecules
- Can leave the vascular space by passing between vascular endothelial cells - Diapedesis.
- One must have an understanding that cells contain a structural cytoskeleton that does allow some degree of change in shape so that the cell is flattened and pseudopodia can be inserted and the cell move gradually between the endothelial cells on the wall
- Intrinsic to all of this is the role of adhesion molecules which are involved in the whole process
- Neutrophils are attracted to an area of inflammation by the LTB4, Interleukin 8, C5a and FMLP - indeed
- Leukotriene B4 from tissue mast cells
- Interleukin 8 from macrophages
- C5a from complement
- FMLP - a component of Bacterial cell walls
- Steroids dampen down and reduce the action of neutrophils by interfering with the expression of adhesion molecules and so reduce the inflammatory response
Neutrophilia - causes
- Acute inflammation: Bacterial infections - neutrophils attack opsonised bacteria, Acute gout, Acute bleed, Diabetic ketoacidosis, Polyarteritis nodosa, Polymyalgia
- Malignancy: As a general response to Malignancy - Lung, breast, gastric etc, Myeloproliferative disorders - CML, PV, MF, Leukoerythroblastic disorder, Lymphoma
- Physiological: Exercise, Pregnancy, Breastfeeding
- Drugs : Steroids, Adrenaline [US Epinephrine] , G-CSF, GM-CSF,
Learn Low LAP (NAP) score in Leukaemia, PNH, TTP otherwise in nonleukaemic neutrophilia, the LAP rises as the neutrophil count rises.
Neutropenia - causes [See also neutropenic sepsis]
- 1 week Post chemotherapy
- Carbimazole, Hydroxyurea, B12/folate deficiency
- Viral, Brucella, TB, Hepatitis C, HIV
- SLE (neutrophil antibodies)