Monocytes: The mysterious cell on the CBC
Swetha*
Staff Nurse, MICU, Kauvery Hospital, Tennur, Tamilnadu
*Correspondence: maha@kauveryhospital.com
Background
A monocyte is part of the innate immune response and functions to regulate cellular homeostasis, especially in the setting of infection and inflammation. They account for approximately 5% of circulating nucleated cells in normal adult blood. The half-life of circulating monocytes is approximately 1-3 days. Monocytopenia, a decrease in circulating monocytes is a common finding in myelodysplastic syndromes. While monocytosis, an increase in circulating monocytes is a common finding in the peripheral blood, especially in association with infection, trauma, medications, autoimmune disease, and some malignancies. When monocytosis is persistent and unexplained, the diagnosis of chronic myelomonocytic leukemia merits investigation.
Monocyte
Monocytes are a type of white blood cells (leukocytes) that reside in your blood and tissues to find and destroy germs (viruses, bacteria, fungi and protozoa) and eliminate infected cells. Monocytes on other white blood cells to help treat injury and prevent infection.
Structure
Monocytes are amoeboid in appearance, and have non granulated cytoplasm. Diameter of 15-22 micrometer. Monocytes are the largest cell type in peripheral blood. Monocytes are mononuclear cells and the ellipsoidal nucleus is often lobulated causing a bean-shaped or kidney shaped appearance. Monocytes compose 2-10% of all leukocytes in the human body.
Typical Monocytes Range
Typically, monocytes make up 2-8% of your total white blood cell count. Absolute monocyte test results can range slightly, depending on the method used for the test and other factors.
Age range |
Absolute monocytes per microliter of blood (mcL) |
| Adults | 0.2-0.95 × 103 |
| Infants from 6 months to 1 yr | 0.6 × 103 |
| Children from 4-10 yr | 0.0-0.8 × 103 |
Functions
- Monocytes destroy foreign substances by phagocytosis.
- These are phagocytosis, antigen presentation and cytokine production are important main functions of monocyte.
- Its play a role in both the inflammatory and anti-inflammatory processes that take place during an immune response.
- It kills the invader or alert other blood cells to help destroy it and prevent infection.
High Monocyte Count (Monocytosis)
Our body may make more monocytes once an infection is detected or if you have an autoimmune disease. If you have an autoimmune disease, cells such as monocytes may go after healthy cells in your body by mistake. People with chronic infections tend to have elevated levels of monocytes too.
Causes of Monocytosis
- Short-term or long-term infections including viral infections such as COVID-19 or mononucleosis or bacterial infections
- Blood disorders such as sickle cell disease or hemolytic anemia
- Autoimmune or inflammatory disorders such as inflammatory bowel disease, sarcoidosis, and lupus
- Short-term or long-term stress.
- Reaction to some medications such as steroids
- Pregnancy
- Splenectomy (removal of your spleen)
- Leukemia and other types of cancer
- Certain medications
- Thyroid irregularities.
Ways to Decrease Monocyte Levels
1) Regular Exercise
Regular exercise is anti-inflammatory. Monocyte counts have also been significantly associated with reduced triglyceride levels, increased insulin sensitivity and decreased body mass index
2) Weight Loss
In obese people, weight loss was accompanied by a significant reduction in monocyte and neutrophil counts. The decrease in circulating monocytes correlated with better insulin sensitivity
3) Omega-3 Fatty Acids
Regular consumption of omega-3 fatty acids found in oily fish such as mackerel and salmon or fish oil supplements may protect against atherosclerosis and heart disease
4) Mediterranean Diet
Some research suggests that the Mediterranean diet could reduce inflammation caused by monocytes. The Mediterranean diet is comprised of foods such as seeds, nuts, vegetables, fruits, whole grains, and monounsaturated fats from olive oil.
5) Moderate Alcohol Intake
Alcohol influences monocyte function. Monocytes exposed directly to alcohol also had a reduced inflammatory response to proinflammatory compounds. Moderate alcohol consumption about 1 or 2 drinks per day is associated with significantly reduced monocyte production of inflammatory cytokines TNF-alpha and IL-1beta. It is also associated with increased production of IL-10, an anti-inflammatory signal
Low Monocyte Count (Monocytopenia)
A monocyte counts that’s lower than the normal range is called monocytopenia. Monocytopenia is when your absolute monocyte count is <= 0.5 × 109 monocytes per liter of blood.
Low monocyte count causes
You can have a low monocyte count because of some conditions, medical treatments, or injuries that lower your total white blood cell count. These include: you can have a low monocyte count because of some conditions, medical treatments, or injuries that lower your total white blood cell count. These include,
- Infections, such as Epstein-Barr virus, adenovirus, or HIV
- Bloodstream infections, such as bacterial sepsis
- Taking steroids or immunoglobulin therapy
- Cancer treatments, such as chemotherapy or radiation therapy)
- Surgery on your stomach or intestines
- Hemodialysis
- A genetic condition called GATA2 deficiency
- Bone marrow disorders, such as aplastic anemia
- Burn injuries
- Certain cancers, especially leukemias and lymphomas. These may include hairy cell leukemia and acute lymphoblastic leukemia or Hodgkin’s lymphoma.
Ways to Increase Monocyte Levels
1) Healthiest ways to strengthen your immune system
Low monocyte levels are usually a sign of a weak immune system. The following good-health guidelines are still the most recommended strategies for improving your immune health
- Don’t smoke.
- Eat a diet high in fruits and vegetables.
- Exercise regularly.
- Maintain a healthy weight.
- Get a good night’s sleep.
- Take steps to avoid infection, such as frequently washing your hands and cooking meats thoroughly.
- Minimize stress.
2) Vitamin B12
In a study of rats with protein deficiency, vitamin B12 supplementation resulted in increased white blood cell count including monocytes. However, supplementation with vitamin B12 did not change white blood cell count in rats that ate normal amounts of protein.
3) Vitamin C
People with low plasma vitamin C had less effective monocytes than those with normal vitamin C levels; furthermore, the first group’s monocytes normalized after they were given vitamin C supplements.
4) Vitamin D
In cell studies, calcitriol (vitamin D) stimulates the growth of human monocytes. Researchers believe that vitamin D is important for monocyte function.
5) Garlic
Rats fed garlic had significantly more monocytes, neutrophils, and lymphocytes than rats not fed with garlic. In cell studies, garlic extracts have also been found to increase the anti-inflammatory signals (IL-10) produced by monocytes.
Conclusion
Monocytes and macrophages in the lung are crucial players in host innate immune defense against pathogens and processes of sterile inflammation involved in lung transplantation, including mechanical ventilation, ischemia-reperfusion, and primary graft dysfunction. A link between monocytes, macrophages, and allograft rejection likely exists and should be further characterized.
Ms. Swetha,
Staff Nurse.