Monocytes in the blood - norms and interpretation of results

Monocytes are the largest immune cells of all types of white blood cells and play an important role in protecting against bacteria and inflammation. What does an elevated monocyte count mean for your health? What factors can reduce their number? Find out about this in the article.

The article is based on the findings of 68 scientific studies

The article quotes authors such as:

• Rockefeller University, New York, USA
• Necker Hospital, Paris, France
• Department of Cell Biology and Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands

Please note that the numbers in parentheses (1, 2, 3, etc.) are clickable links to peer-reviewed scientific studies. You can follow these links and read the original source of information for the article.

What are monocytes?

The front line of defense for your immune system

Monocytes are the largest type of white blood cell.
They help fight bacteria, viruses and other infections in your body. Along with other types of white blood cells, monocytes are a key part of your immune response. Only about 1% of your blood contains white blood cells, but they play a huge role in protecting against disease. Approximately 2 to 10% of all leukocytes are monocytes. (1) Your bone marrow produces monocytes and releases them into your bloodstream. Once they reach tissues in your body, they are called macrophages . There they isolate and devour germs and other harmful microorganisms. They also get rid of dead cells and promote the immune response. After leaving the bone marrow, monocytes circulate in the blood for several days before they enter tissues where they become macrophages or dendritic cells. (1, )

An example of how monocytes from the blood move into
an atherosclerotic plaque , becoming macrophages.
Monocytes adhere to the endothelium of blood vessels at sites of tissue damage, which leads to their activation and migration into the subendothelial space. Upon tissue entry, the monocyte differentiates into a macrophage. (source) Monocytes protect against viral, bacterial, fungal and protozoal infections. They kill microorganisms, absorb foreign particles, remove dead cells and enhance the immune response. (, 1, , )

However, they may also be involved in the development of inflammatory diseases such as arthritis and atherosclerosis. In this article, we'll take a closer look at how monocytes work and how they may be involved in disease. (, , )

Monocyte formation

All blood cells come from common parent cells called hematopoietic stem cells . In adults, blood cells are produced primarily in the bone marrow; this process is called hematopoiesis. The process of producing monocytes in particular is called myelopoiesis . (, )

Mechanisms of myelopoiesis (monocyte formation) during homeostasis and during different phases of infection and inflammation, illustrating important feedback loops between affected tissues and bone marrow.

Myelopoiesis is subject to a complex regulatory system, including such factors as:

• Transcription factor SPI1 (, , , )
• Cytokines: SCF (stem cell factor), GM-CSF (granulocyte-macrophage-colony-stimulating factor), M-CSF (macrophage colony-stimulating factor, CSF1), cytokines IL-3 and IL-6, and interferon IFN-gamma. (, , )

Monocytes live on average 3 days before undergoing apoptosis (programmed cell death). They live longer during periods of high inflammation; as soon as the inflammation disappears, monocyte death occurs. Such programmed death is necessary to prevent aggressive actions of immune cells from continuing inflammation and creating an autoimmune reaction. (, )

The norm of monocytes in the blood

To determine the level of cells, the patient is prescribed a general clinical blood test, which determines how many elements are present in a unit of its volume. Normally, an adult should have 3-11 monocytes per 100 leukocytes. To find out the content of all white cells, a leukogram is done - an advanced analysis that determines the leukocyte formula.

The decoding may indicate the absolute content - monocytes abs or monocytes mono - percentage.

How many leukocyte cells should be in the analysis of adults and children can be seen in the table.

Normal monocyte count

Normal ranges for monocytes can be expressed in several different standard units of measurement. Ask your doctor to help you interpret lab results.

Normal Monocyte Ranges:

• 0.2 – 0.8 x10^9/l (laboratory reference values ​​0.08 – 1.5x10^9/l)
• 1 – 10% (laboratory reference values ​​4 – 12.5%)

Monocyte counts in normal ranges help reduce the risk of developing and poor outcomes:

• viral, bacterial and fungal infections ()
• heart disease ()
• obesity()
• diabetes ()
• increase in mortality ()

Elevated monocyte count

Monocytosis is a condition in which the number of monocytes circulating in the blood increases to more than 0.8x10^9/L in adults.

Diseases with elevated monocyte levels

• Circulatory disorders (myelodysplastic disorders, acute monocytic, chronic myelomonocytic leukemia, Hodgkin and non-Hodgkin lymphoma) (, , )
• Infections (tuberculosis, viral infections, bacterial endocarditis, brucellosis, malaria, syphilis) (, , , , )
• Autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease) (, , )
• Sarcoidosis ()
• Malignant tumors (ovary, breast, rectum) ()
• Heart attack - infarction ()
• Appendicitis ()
• HIV infection
• Depression()
• Obesity ()
• Severe pneumonia ()
• Alcoholic liver disease ()

Monocytosis most often occurs during and after chronic inflammation or infection. () However, several other problems may be associated with monocytosis: heart disease, depression, diabetes and obesity. (, , )

The most common conditions and diseases associated with high monocyte levels are:

• Chronic (long-term) inflammation of any etiology ()
• Infections such as tuberculosis, malaria and syphilis (, , )

Monocytes are involved in human disease both directly through their functional effects and indirectly through their differentiation into macrophages . Diet influences the number of nonclassical monocytes, monocyte migration, and cytokine production, the effects of which are counteracted by fasting. Additionally, the epigenetic landscape is altered by metabolites in a process called innate immune memory. In atherosclerosis, monocytes differentiate into foam cells, which secrete proinflammatory cytokines and chemokines, accumulate lipids, and possibly participate in calcification. Monocytes exhibit high heterogeneity and their functions can be impaired, as in COPD , while the location of monocytes appears to be critical in lung cancer , with monocytes close to tumors being immunocompromised. Finally, monocytes infiltrate the brain in neurodegenerative diseases such as Alzheimer's disease .
(source) Few symptoms of inflammatory diseases are associated with monocytosis itself. According to many scientists, such symptoms arise from diseases associated with the development of monocytosis. () These symptoms consist of: fever (), pain (), tissue swelling. ()

Leukocytes - what are they?

Leukocytes are the body’s protective army. They make up a large group of white blood cells whose purpose is to rid the body of infections. Leukocytes take part in allergic, autoimmune and tumor processes. White cells are divided into types, which are responsible for their specific function.

A complete blood count shows the total number of cells. The leukocyte count is responsible for accurately identifying the cell types that cause an increase (leukocytosis) or decrease (leukopenia) in white cells in the blood. The formula can be found in an expanded form of a blood test. There are five types of cells, their number and relationship to each other.

The blood test is assessed using an automatic analyzer, which calculates the percentage of each type of the total number of cells. The device also calculates the white blood cell count per liter of blood.

Additionally, a visual assessment of the blood smear using a microscope may be required. A “manual” check of analyzes may be necessary in the following cases:

• Changes in the leukocyte formula; • There are altered or immature cells; • Signs of anemia are visible; • Reduced platelet count.

If the analysis is processed manually, only the percentage will be visible. Each type of assessment allows you to correctly diagnose diseases, understand their causes and prescribe the correct treatment.

Low monocyte count (monocytopenia)

With monocytopenia, the number of monocytes circulating in the blood decreases to less than 0.2 × 10^9/L in adults. Monocytopenia itself does not appear to cause symptoms, and patients usually experience only symptoms associated with the associated condition. Similar symptoms may include fatigue and fever. (, )

Diseases and conditions with low monocyte levels

• Aplastic anemia ()
• Leukemia (hairy cell leukemia, chronic lymphocytic leukemia) ()
• Carrying out chemotherapy ()
• Radiation therapy ()
• monoMAC syndrome (monocytopenia and mycobacterial infection) ()
• Severe burn injuries ()
• Rheumatoid arthritis ()
• Systemic lupus erythematosus ()
• HIV infection ()
• Vitamin B12 deficiency ()
• Corticosteroid therapy (transient monocytopenia) ()
• Administration of drugs: interferon-alpha and TNF-alpha ()

Lymphocytes are the final link

Lymphocytes are responsible for the final action of the immune system, processing antigens already prepared by monocytes and other cells. They are responsible for acquired immunity, which will prevent the infection from acting again. Lymphocytes produce antibodies and memory cells. Like other cells, lymphocytes are produced in the bone marrow but circulate in both the blood and the lymphatic system. Cell maturation is influenced by the thymus and lymph nodes. The group of lymphocytes is the second most numerous in the blood.

To identify cells in the blood, a special test called immunophenotyping is used. Thanks to this study, it is possible to determine the specific number of this type of cell. Determining specific types of lymphocytes makes it possible to diagnose and treat diseases of the immune system, HIV infections and others.

The leukocyte formula indicates the increase and decrease in the number of lymphocytes. Both indicators are very important. Lymphocytosis, or an increase in the number of cells, indicates viral infections, as does a decrease (lymphopenia). A decrease in the number of lymphocytes significantly reduces the protective function of the body, which is typical for people with immunodeficiency.

Link between elevated monocyte levels and health status

Atherosclerosis

Monocytes and macrophages are involved in the development and worsening of atherosclerosis, which can lead to various heart diseases and stroke. ()

The accumulation of monocytes and macrophages loaded with cholesterol leads to plaque rupture and thrombus formation. (source)

Monocytes accumulate in blood vessels and promote the development and rupture of atherosclerotic plaques, which block the blood vessels. (, , )

As atherosclerosis progresses, the number of monocytes in the blood tends to increase. ()

Chronic inflammation in diabetes

A clinical study found no association between diabetes mellitus and the number of circulating white blood cells, but monocytes were significantly more numerous in people with complications of diabetes mellitus. (42)

Some scientists believe that monocytes may be responsible for the harmful inflammatory complications of type 2 diabetes. Studies have shown that monocytes secrete the cytokines TNF-alpha, IL-6 and IL-1 in both type 1 and type 2 diabetic . These pro-inflammatory molecules (cytokines) are thought to contribute to the development of blood vessel diseases (such as atherosclerosis). (, , , , , )

Mortality rates and monocyte counts

In a large study of more than 4,000 adult patients in a Swiss hospital, people with monocytosis had more and more severe than those who did not have elevated monocyte counts. In addition, patients with monocytosis had lower survival rates during their hospital stay. ()

In a separate study of older Korean men and women, monocytosis was associated with an increased risk of cardiovascular and cancer death. ()

But this relationship has not been studied well enough to say for sure that monocytosis can predict mortality rates. However, modern research has largely supported this association. (, , )

Heart recovery after a heart attack

After a heart attack (infarction), monocytes repair damage to the heart by destroying damaged and dead heart cells. However, animal studies suggest that increased monocyte counts are associated with impaired healing after infarction. (, )

Hormones and increased monocytes

Leptin

The hormone leptin increases the number of monocytes and their production of cytokines, since leptin is a pro-inflammatory cytokine. () Leptin levels correlate with body weight: in obesity, leptin is often elevated.

Decrease in estrogen during menopause

An increase in the number of monocytes in the blood of women has been found during menopause, when estrogen levels decrease. In addition, the number of monocytes decreases after estrogen replacement therapy. ()

A growth hormone

Growth hormone increases the number of white blood cells, including monocytes. ()

Testosterone

Testosterone injections increased the number of monocytes, granulocytes and large lymphocytes in mice. ()

What level is considered low?

Monocytes can be easily distinguished in a laboratory study by their large size and large oval nucleus without constrictions.

The norm of monocytes in a blood test is taken into account by absolute value and relative indicator. Leukocyte cells are counted from a stained blood smear in a certain volume. It is most convenient to use the calculation per liter.

The lower limit of normal for monocytes is set for children - 0.05 x 109/l, for adults the figure is 0.08 x 109/l - the upper limit, zero cell value is considered low. You can read more about the normal range of monocytes in children here.

Based on the relative content of monocytes among the entire group of leukocytes, the rate below normal is estimated in children, depending on age, at less than 3–5%; in adults, a decrease from 3% to zero.

Most often, when the immune system is suppressed, a reduced level of leukocytes in general, as well as lymphocytes along with monocytes, is determined.

Any microorganisms that come into contact with the skin become dangerous.

• What are monocytes in a blood test and their norm in women and men by age

Ways to lower monocyte levels

Monocytosis is a condition that requires diagnosis and treatment by a healthcare professional. Talk to your doctor before trying any strategies to reduce your monocyte count.

Regular exercise

Regular physical activity has an anti-inflammatory effect . In one study, monocytes were significantly reduced by 6 weeks of cycling training in overweight women who did not exercise regularly.

As
we age , there is an increase in general inflammation and a decrease in immune capabilities. In particular, the number of monocytes increases . But physical activity and diet can reduce the level of monocytes, and transfer macrophages from the M1 type to the less inflammatory M2 type.
(source) Monocyte count (decrease in monocyte count) was also significantly associated with decreased triglyceride levels, increased insulin sensitivity, and decreased body mass index (weight loss). All these changes in the body occur under the influence of physical activity. ()

Weight loss

In obese people, weight loss was accompanied by a significant decrease in the number of monocytes and neutrophils . A decrease in the number of circulating monocytes correlated with better insulin sensitivity of body tissues, which prevented the development of metabolic syndrome. ()

Omega-3 fatty acids

Regular consumption of omega-3 fatty acids, found in fatty fish such as mackerel and salmon, or in fish oil supplements, may protect against atherosclerosis and heart disease. ()

People taking fish oil supplements were less likely to show inflammation in the walls of blood vessels caused by monocyte activity. This effect was not as pronounced in people already taking special medications to treat peripheral blood vessel disease. ()

Moderate alcohol consumption

Alcohol affects monocyte function. In one study, the monocytes of people who drank moderate amounts of alcohol were less active, even after just one drink. Monocytes directly exposed to alcohol also had a reduced inflammatory response to proinflammatory proteins. (, )

Moderate alcohol consumption, about 1 or 2 standard drinks per day, is associated with significantly reduced monocyte production of the inflammatory cytokines TNF-alpha and IL-1beta. Alcohol is also associated with increased production of the cytokine IL-10, which is an anti-inflammatory protein. (, )

However, we do not recommend increasing alcohol consumption in order to relieve inflammation. Talk to your doctor about more appropriate anti-inflammatory actions.

Mediterranean diet

Some studies demonstrate that the Mediterranean diet can reduce inflammation caused by monocytes. (, )

PYRAMID OF THE MEDITERRANEAN DIET

The Mediterranean diet consists of foods such as seeds, nuts, vegetables, fruits, whole grains and monounsaturated fats from olive oil.

Starvation

Intermittent or prolonged fasting can reduce the proinflammatory activity of monocytes. For example, the short-chain fatty acid β-hydroxybutyrate, which when released from the liver during prolonged fasting , has been shown to suppress the production of the cytokines IL-1β and IL-18 by human monocytes, which was induced by the NLRP3 inflammasome. ()

Calorie restriction has beneficial effects on many chronic metabolic disorders such as type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular disease, and intermittent fasting is sufficient to reduce the number of all monocyte populations in healthy individuals. ()

Taking cortisol

When a single dose of cortisol is administered, the number of monocytes decreases by 90% 4-6 hours after receiving the drug. This decline in numbers lasted for about 24 hours. Subsequently, monocyte levels return to normal 24 to 72 hours after cortisol treatment. ()

Taking estrogen

According to one study, estrogen (and possibly also progesterone) reduces the number of monocytes by preventing their production. This mechanism could explain why cell-mediated immunity appears to be suppressed during pregnancy . ()

Medicine: infliximab

Infliximab (monoclonal antibody TNF-alpha) is an immunosuppressive drug prescribed to treat inflammatory diseases such as Crohn's disease, ulcerative colitis, and rheumatoid arthritis. (, , )

Infliximab inhibits monocytes, which may help reduce inflammation in patients with chronic inflammatory diseases. ()

Symptoms of decreased monocytes in patients with aplastic anemia

With aplastic anemia, patients experience a sharp depression of the hematopoietic function of the bone marrow, accompanied by a powerful inhibition or complete cessation of blood cell growth processes.

The analyzes note a sharp decrease in the number of leukocyte and platelet cells, as well as severe anemia.

Symptoms of the disease are manifested by severe dizziness, a pronounced decrease in performance, pallor and yellowness of the skin, increased heart rate, the appearance of a heart murmur, heart rhythm disturbances, severe shortness of breath, poor exercise tolerance, hemorrhagic symptoms (the appearance of petechiae, bleeding, an increase in the volume and duration of menstrual periods). bleeding, prolongation of bleeding time from scratches and wounds, etc.).

There is also a sharp suppression of immunity and an increase in the incidence of infectious diseases (usually of fungal or bacterial origin).

Link between low monocyte levels and health status

Cardiovascular diseases

Of all white blood cells, monocyte counts have the strongest association with the incidence of cardiovascular disease in people without any symptoms. Lower monocyte levels are directly associated with lower cardiovascular risk of disease and death. ()

Link of monocytes (increased levels) in cardiovascular diseases (source)

Susceptibility to infections

Monocytes are involved in the immune response to infection , so it is not surprising that low monocyte counts are associated with increased infection rates. Monocytopenia is directly associated with monoMAC syndrome: increased susceptibility to mycobacterial infections, fungal infections, and human papillomavirus (HPV). (, )

Hematopoietic disorders

Monocytopenia is associated with blood disorders such as myelodysplasia, acute myelogenous leukemia, chronic myelomonocytic leukemia, and lymphomas. If you are concerned about your low monocyte count and your possible risk of these blood disorders, talk to your doctor about additional tests available. ()

Cervical cancer

Patients with primary immunodeficiency have insufficient numbers of monocytes and are susceptible to severe, persistent human papillomavirus (HPV) infections, which can cause cervical cancer. If you have problems with your monocytes, talk to your doctor about strategies to prevent cervical cancer, especially if you have not been vaccinated against HPV. (, )

How to normalize the level of monocytes in the blood?

If, when interpreting the tests, deviations from the norm are revealed, it is necessary to conduct an in-depth examination and accurately determine the cause of the pathology.

The diagnosis of the disease is carried out by a therapist, if necessary, including:

• infectious disease specialist;
• rheumatologist;
• allergist;
• gastroenterologist;
• hematologist.

To normalize your condition, strictly adhere to the doctor’s recommendations and follow all his instructions.

What to do if monocytes are higher than normal?

If the concentration of cells in the blood is increased, direct all efforts to treat the disease that caused the pathology.

During therapy, lead a healthy lifestyle:

• give up bad habits;
• take a walk in the fresh air every day;
• dress according to the weather;
• spend at least 8 hours a day sleeping;
• drink 2 liters of clean water per day.

Pay special attention to nutrition. Include foods that strengthen immune defenses in your diet. Enrich it with easily digestible carbohydrates and proteins:

• rice, oatmeal;
• natural honey;
• milk; cottage cheese;
• lean meat;
• sea ​​fish;
• eggs.

To lower monocytes to normal, regularly prepare chicken broth, eat spinach, garlic, and walnuts. Eat salads made from white cabbage, red bell peppers, and grapes.

To strengthen the body's resistance to infections, vitamins C, D, A, and group B are needed. They can be obtained from the liver of sea fish, sour cream, black currants, lemons, dried apricots, and hard cheese.

What to do if monocytes are below normal?

A low number of monocytes means a failure of hematopoietic function. It is important to find out what is causing the problem and start treatment immediately.

During this period, a person needs moderate physical activity, proper rest and proper nutrition. Eliminate fast food, canned food, and foods rich in preservatives and dyes from your diet. Avoid alcohol and fatty meats. Limit your salt intake.

To improve bone marrow function, the following are useful:

• black chocolate;
• fresh carrots;
• seaweed;
• chicken eggs;
• peanut;
• walnuts;
• fatty sea fish.

To provide the body with iron and improve blood, boiled or lightly fried beef liver, buckwheat porridge, and pomegranate juice are recommended.
The level of monocytes is examined during each general blood test. This makes it possible to timely identify pathological processes and begin treatment. Regular exposure to fresh air, proper and nutritious nutrition, physical exercise, and timely treatment of viral and bacterial infections will help reduce the risk of developing monocytosis and monocytopenia.