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What are Monocytes?

Monocytes are one of the largest types of WBC, which helps to regulate the immune system and fight against foreign particles or any kind of infection in our body. It is an immune cell manufactured in bone marrow travelled through the blood to the tissues in the whole body, where it changed to a dendritic cell or macrophage. Macrophages kill microorganisms, remove dead cells, ingest foreign materials and boost the immune system. Monocyte is a type of phagocyte and a type of white blood cells.

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Any kind of infection in the body, like bacterial, viral or fungal, causes an increase in monocyte levels. It happens because the body starts fighting the infection and creates monocytes to fight the foreign body. A monocyte high is also caused by autoimmune disorders, chronic infections and sometimes by stress too.

Anything that causes suppression of the immune system causes low monocyte counts. There are various causes of suppression of the immune system such as chemotherapy and radiation therapy, cancer, HIV, and AIDS that weakens the body immune system and bloodstream infection, sepsis.

Structure of Monocyte

The monocytes are the largest cells that are present in the peripheral blood. They have a diameter that is between the range of 14 to 20 micrometres. The appearance of the cell is somewhat irregular in shape, and it has a kidney-shaped or an oval-shaped nucleus present along with some cytoplasmic material. The nucleus to cytoplasm ratio of monocytes is quite high, which is 3:1. The nucleus of the monocyte is quite prominent and is folded. There are a large number of granules present in the cytoplasm. These granules of monocytes are known as cytoplasmic granules. The number of these granules is more towards the cell membrane. There is a chromatin net present in the nucleus. There are also chromatin clumps that are seen in the nuclear membrane towards its inner side. On the surface of the monocyte, there are some blebs and ruffles that have some functional significance.

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Since Monocytes are phagocytic and motile in nature, the irregular formation and ruffles present on the surface make the repulsive forces a bit less, with the negatively charged groups approaching the cell. There are numerous mitochondria present in the cytoplasm that are small in size and somewhat elongated. We can also see a golgi complex present along with a centrosome inside the nucleus. In addition, there are many microvilli present on the cell membrane that helps in the movement and adherence of monocytes to the other cells. The cytoplasmic granules have a very smaller diameter which is of about 0.05 to 0.2 micrometres. However, they are homogeneous and dense.

Presence of Monocytes

A certain amount of monocytes migrate in and out of the required organ tissues.

In the spleen, quite good numbers of monocytes migrate to the tissue from the body and reside there to give rise to numbers of macrophages which essentially fight infection and clear dead cells.

How to Increase monocytes- Low monocytes treatment

There are several ways to increase monocytes levels in our body, such as regular exercise, maintaining a healthy weight, minimizing stress levels, smoking cessation, and last but not least good sleep.

Conditions associated with Monocyte low counts (Monocytopenia)

There are various conditions associated with Monocytopenia (deficiency of monocytes). Cancer chemotherapy helps to improve the quality of life of a human being, also causes various conditions such as Monocytopenia due to the use of chemotherapeutic agents. Other reasons for Monocytopenia are:

  • Leukaemia

  • Vitamin B12 deficiency

  • Rheumatoid arthritis

  • Corticosteroid therapy

  • HIV infection

  • Radiation therapy

  • Sometimes severe burns too

Monocyte High Counts (Monocytosis)

Monocytosis, state of the increased number of monocytes in the blood, which may indicate various diseases such as,

  • Necrosis

  • Red blood cell regeneration

  • Atherosclerosis

  • Sarcoidosis

  • Immune-mediated diseases.

Role of the Immune system in Monocytopenia and Monocytosis

The immune system plays a vital role in our survival. Still, in the case of monocytopenia and monocytosis, both conditions are harmful to the body means hyperactivity of the immune system leads to various severe diseases and sometimes may cause death too.

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FAQs on Monocytes

1.What is the role of Monocytes?

Like all other WBC, monocytes are an integral part of the immune system’s ability to kill invaders and also work in healing and repair. Monocytes are formed in the bone marrow and circulated throughout the body by the bloodstream for several days. They are 5-10% of the total WBC circulated in the bloodstream of a healthy body. Some of them come on demand of the body needs to form precursors of two other types of WBC: dendritic cells and tissue macrophages. The main function of those is to understand the environment and release a pool of dendritic cells and macrophages, as needed. Now we know that monocytes have protein tags on the outside, and they behave as per their needs.

There are three types of monocytes. classical monocytes comprise 80% of total monocytes, and the rest, 20%, are classified on the presence of their protein tags.

2.What is the monocytes blood test?

A blood differential test is done for total monocyte count. It also helps if some types of WBC are abnormal or immature. The differential test is done in the same way as other blood tests are done. The general process involves the following steps.

  • A blood sample is collected from your arm. For this test, you don't have to do any fasting or operation. 

  • After the collection of blood, the pathologist counts the different types of WBC in blood cells. 

This diagnosis is made to find out any infection conditions like anaemia or leukaemia; the normal range of monocytes is 2 to 8% of the total WBC count. Other tests that could be known are eosinophils count, lymphocytes count, neutrophils count, and young neutrophils count. A rise in overall WBC count might be the response of acute stress, blood disorders, infection, inflammation, and sometimes immune response too.

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