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Updated
in collaboration with
Mathilde Hunault-Berger (Head of the Blood Diseases Department at the University Hospital of Angers)
Neutrophils are part of the leukocytes, the white blood cells that allow the body to defend itself, in particular against bacterial infections. The explanations of Professor Mathilde Hunault-Berger, specialist in blood diseases at the University Hospital of Angers.
What are neutrophils?
Polymorphonuclear neutrophils (or PNN) cells are part of the leukocytes, these white blood cells which intervene in the first line of defense against attacks or any infection. “They are so called because of their “multi-lobed” nucleus (their nucleus contains several lobes, unlike monocytes) and the coloration they take on when in contact with special dyes”underlines Pr Mathilde Hunault-Berger, doctor specializing in blood diseases at the University Hospital of Angers.
Neutrophil polymorphonuclear cells thus represent 65% of all leukocytes. “Each type of white blood cell will play a specific role depending on the substances present in their granulation”says the specialist.
Along with neutrophils, eosinophilic granulocyte cells and basophils are also part of the same family of leukocytes or white blood cells. “Produced by the bone marrow, neutrophils are the first cells to mobilize in the event of a bacterial infection, eliminating the pathogen circulating in the blood. This response is a totally normal mechanism” explains Professor Hunault-Berger.
A blood test to measure neutrophils
A simple blood test makes it possible to count these cells, ie to quantify the number and type of leukocytes present in the blood. Thus, a healthy individual harbors between 4000 and 8000 neutrophils per mm3 of blood volume. The level of these cells can temporarily increase during pregnancy or during physical exercise (this number can then increase to 12,000/mm3, for example). This reaction is normal. However, the first cause of an increase in the number of polymorphonuclear neutrophils remains smoking. “However, this situation is not pathological. It is a reactive increase of the cells”, reassure the doctor.
Any inflammatory reaction or infection is also likely to lead to an increase in these cells, through an immune response effect. In the event of inflammation, during a microbial infection for example, certain substances; like cytokines, are released in the body and will stimulate the production of neutrophil polynuclear cells.
“Certain diseases can lead to an abnormal increase in the level of polymorphonuclear neutrophils. In the event of cancer, or leukemia, the level of these blood cells can then reach 100,000 /mm3 for example”adds the specialist.
This can happen in chronic myeloid leukemia, a blood disease that causes an overgrowth of neutrophil cells in the bone marrow. “A blood test can point to this track, but generally other symptoms are also associated. Additional examinations are necessary to refine the diagnosis and understand the reason for an increase in the level of neutrophils in the blood”, says the hematologist.
Which cancer causes neutrophils to increase?
Certain types of cancer can also cause an increase in neutrophil counts in the blood, as do certain inflammatory diseases, such as rheumatoid arthritis, for example. We then see an increase in white blood cells, due to the immune response effect.
