Neutrophils are white blood cells that play a major role in the immune system. Neutrophilia refers to a higher than normal number of neutrophils, which may be caused by infection, inflammation or chronic disorders such as chronic myeloid leukemia. The neutrophil count is a valuable tool used by doctors to diagnose a wide variety of medical conditions, in conjunction with other tests.
White blood cells, or leukocytes, are manufactured in the bone marrow and are divided into a number of subtypes, including neutrophils, which are polymorphonuclear granulocytes. This refers to their nucleus, which is multi-lobed, and the granular nature of their cytoplasm, allowing easy distinction under the microscope in the lab. Neutrophils can be divided into bands, which are newly formed neutrophils, and segmented neutrophils, which are mature.
The immune system is complicated and consists of numerous processes designed to protect the body from foreign bodies such as bacteria. Neutrophils are involved in the first response to any attack. When the body recognizes something foreign, such as bacteria, a series of signals are sent, and neutrophils gather at that point. The neutrophils then phagocytose, or envelop the foreign body, and kill it.
Acute infectious conditions such as chicken pox as well as bacterial infections and non-infectious conditions such as burns, heart attacks and chronic myeloid leukemia may cause neutrophilia. Some drugs, such as corticosteroids, may also raise neutrophils as a side effect. While some people have naturally higher neutrophil counts than others, very elevated counts should generally be investigated.
There are some non-harmful causes of slight neutrophilia, such as stress or exercise. Newborn babies tend to have higher neutrophil levels for about three days after birth. Post-operatively, a significant rise in neutrophils may be seen within three hours. Cigarette smoking has also been associated with this condition.
A leukemoid reaction, or raised white blood cell count, may be caused by drugs, infections and hemorrhage, among other causes. It results in a left shift, which means there is a higher proportion of younger neutrophils and neutrophil-precursor cells. This, simply put, shows that the body is trying to produce more white blood cells to fight off an infection or attack of some sort.
Neutrophilia is diagnosed with a blood test and microscopic examination. When checking for the condition, the doctor will normally take into account the total white blood cell count and the breakdown into the different kinds of white blood cells. This allows for more accurate diagnosis of the underlying cause of the neutrophilia.