Table of ContentsView AllTable of ContentsTypesNormal RangeFunctionsAssociated ConditionsFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Types
Normal Range
Functions
Associated Conditions
Frequently Asked Questions
Monocytesare a type ofwhite blood cell(leukocyte) that plays an important part in theimmune system’sability to destroy invaders like viruses, bacteria, and fungi. Monocytes form in the bone marrow and are released into the blood. They can also help support the removal of infected cells and aid in healing and repair of the body.
Certain health conditions can cause you to have too few or too many monocytes. For example, ahigh monocyte countin a blood test can happen with certain infections or blood cancers. It can also be a sign of stress.
This article will go over the types of monocytes and their functions. It also covers various health conditions that can cause monocytes in your blood to be too high or too low.
Monocytes and Other Types of White Blood Cells
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Monocyte Types
Researchers used to think that the main role of monocytes was sensing the environment and replenishing the pool of tissuemacrophagesand dendritic cells, which are two other types of white blood cells.
Now, we know that different kinds of monocytes have unique markers or protein tags on the outside of them. These different types of monocytes act differently in the body.
The three kinds of human monocytes are:
Why Is My White Count Low?
As for the role that different kinds of monocytes have in the immune system, researchers are still figuring that out. We know a lot more about mouse monocytes than we do about human monocytes.
“Inflammatory” and “anti-inflammatory” are also applied to human monocytes. Whether they have these terms applied to them is based on the protein tags (or receptors) that are found on the outside of these cells.
However, we don’t know exactly what proportion of monocytes in humans can move well enough to go in and out of the body’s tissues. Research suggests that some monocytes can “eat” (engulf) and digest (phagocytize) invaders without actively promoting inflammation.
What Is the Normal Range for Monocytes?
The normal range for monocytes in healthy adults is 2% to 8%. The normal range for the absolute number of monocytes is 200-800 per cubic millimeter.
However, the lab that processes your blood sample might use different ranges to report your monocyte count. If you aren’t sure if your levels are normal, ask your provider.
What Is a Normal WBC?
Monocyte Functions
Monocytes form in thebone marrow, and then get released into the blood where they will circulate for several days.
Monocytes are best known for their role as “reserve forces” in the body, as they can be called on to form the beginnings (precursors) of two other types of white blood cells: tissue macrophages and dendritic cells. Monocytes also have other roles in infection and disease.
Monocytes in the Spleen
A good number of human monocytes move into the tissues of your body where they help make the macrophages that fight infection and clean up dead cells.
Thespleenhas all major types of mononuclearphagocytesin it, including macrophages, dendritic cells, and monocytes. The spleen is an active site for theinnate immune system.
The Function of the Spleen
Monocytes and Innate Immunity
Innate immunity is theimmunitythat you are born with. It’s not the same as the targetedimmunity you get from a vaccineor after recovering from an infectious illness. The innate immune system works in a different way, includingphagocytosisand inflammation.
Macrophages in the spleen clean up debris and old cells from the blood, but they also helpT-lymphocytesrecognize foreign invaders—what’s calledantigenpresentation.
Antigen presentation is where the innate immune system ends and theacquired or learned immune responseto a specific foreign invader starts.
Fighting Infection
Some monocytes turn intomacrophages in the tissues and act sort of like Pac-Man, gobbling up bacteria, viruses, debris, and any cells that have been infected or are sick.
Other monocytes turn into dendritic cells in the tissues where they work with T lymphocytes. Macrophages can also present antigens to T-cells. However, dendritic cells are considered the “specialists” at this task. They accumulate debris from the breakdown of bacteria, viruses, and other foreign material and present it to the T-cells so they can see it and form an immune response to the invaders.
Like macrophages, dendritic cells are able to present antigens to T-cells in a certain context, as if to say, “Do you think we should be doing more about this?”
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When you have acomplete blood count (CBC)blood test done with a breakdown of the different cells (differential count) the white blood cell monocytes are counted and the number is reported. You will also see what percentage of total white blood cells are monocytes.
How to Understand Your Blood Test Results
Researchers are still learning but they think that in humans, monocytes might also be involved in certain diseases including microbial infection,shock, organ injuries,osteoporosis,cardiovascular disease,metabolic diseases, andautoimmune diseases.
Monocytes in Listeria
Listeria monocytogenesis a species of bacteria that can cause listeriosis, a type of foodborne illness. Listeria precautions are one of several given during pregnancy because Listeria can cause meningitis in newborns as well as pregnancy loss. People who are pregnant are often advised not to eat soft cheeses, which can have Listeria in them.
What Is Listeria?
Monocytes in Leukemia
If the line of cells that make monocytes get disordered, the cells may start making copies of themselves out of control.
Acute monocytic leukemia is a form of acute myelogenous leukemia. In this type, more than 80% of the disordered cells are monocytes.
Inchronic myelomonocytic leukemia(CMML), there are increased numbers of monocytes and immature blood cells in the bone marrow and circulating in the blood.
What Causes of Myelodysplastic Syndromes (MDS)?
Monocytes in Lymphoma and Other Cancers
Monocytes may have actions related to tumors and cancerous behaviors of white blood cells called lymphocytes. These diseases are known as lymphoproliferative diseases.
The presence of macrophages and their activities in tumors have been associated with enabling the tumor cells to build a blood supply and to invade and travel through the bloodstream.Knowing this might help researchers create cancer therapies that target macrophages to prevent metastasis and tumor growth.
Some providers use the absolute monocyte count as an indicator of risk or a worseprognosisbefore treatment in people with cancer.
For example, an increased number of monocytes above a certain threshold is associated with worse outcomes in patients with T-cell lymphomas andHodgkin’s disease.
The lymphocyte-to-monocyte ratio may also help identify high-risk patients in diffuse largeB-cell lymphomaand untreatedmetastaticcolorectal cancer.
What Are Myeloid Cells?
Summary
Frequently Asked QuestionsInfections can cause monocytes to increase. Some people with viral illnesses like COVID may have higher than normal levels of white blood cells in their blood, including monocytes.Learn MoreWhite Blood Cells and COVIDMonocytopenia means you have lower-than-normal numbers of monocytes in your blood.Monocytosis means the number of monocytes in your blood is higher than normal.
Infections can cause monocytes to increase. Some people with viral illnesses like COVID may have higher than normal levels of white blood cells in their blood, including monocytes.Learn MoreWhite Blood Cells and COVID
Infections can cause monocytes to increase. Some people with viral illnesses like COVID may have higher than normal levels of white blood cells in their blood, including monocytes.
Learn MoreWhite Blood Cells and COVID
Monocytopenia means you have lower-than-normal numbers of monocytes in your blood.
Monocytosis means the number of monocytes in your blood is higher than normal.
White Blood Cell Counts and Cancer
10 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Karlmark KR, Tacke F, Dunay IR.Monocytes in health and disease - Minireview.Eur J Microbiol Immunol (Bp). 2012;2(2):97–102. doi:10.1556/EuJMI.2.2012.2.1Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: a systematic approach to a common hematologic finding.Current Hematologic Malignancy Reports. 2021;16(3):267. doi:10.1007/s11899-021-00618-4Patel AA, Yona S.Inherited and environmental factors influence human monocyte heterogeneity.Frontiers in Immunology. 2019;10:2581. doi:10.3389/fimmu.2019.02581Justiz Vaillant AA, Jan A.Physiology, immune response. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.Territo M.Monocyte disorders. Merck Manual.Rogalla D, Bomar PA.Listeria monocytogenes. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.Smith HA, Kang Y.The metastasis-promoting roles of tumor-associated immune cells.J Mol Med (Berl). 2013;91(4):411–429. doi:10.1007/s00109-013-1021-5Tadmor T.Monocytes, monocytic myeloid derived suppressor cells and lymphoma: how tight is the knot of the tie?J Leuk(Los Angel) 2013, 1:4. doi:10.4172/2329-6917.1000e103Lin GN, Liu PP, Liu DY, Peng JW, Xiao JJ, Xia ZJ.Prognostic significance of the pre-chemotherapy lymphocyte-to-monocyte ratio in patients with previously untreated metastatic colorectal cancer receiving FOLFOX chemotherapy.Chin J Cancer. 2016;35:5. doi:10.1186/s40880-015-0063-1Knoll, Schultze, Schulte-Schrepping.Monocytes and Macrophages in COVID-19.Frontiers in Immunology. 2021;0. doi:10.3389/fimmu.2021.720109Additional ReadingEigenbrod T, Dalpke AH.Bacterial RNA: An underestimated stimulus for innate immune responses.J Immunol. 2015;195(2):411-8. doi:10.4049/jimmunol.1500530
10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Karlmark KR, Tacke F, Dunay IR.Monocytes in health and disease - Minireview.Eur J Microbiol Immunol (Bp). 2012;2(2):97–102. doi:10.1556/EuJMI.2.2012.2.1Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: a systematic approach to a common hematologic finding.Current Hematologic Malignancy Reports. 2021;16(3):267. doi:10.1007/s11899-021-00618-4Patel AA, Yona S.Inherited and environmental factors influence human monocyte heterogeneity.Frontiers in Immunology. 2019;10:2581. doi:10.3389/fimmu.2019.02581Justiz Vaillant AA, Jan A.Physiology, immune response. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.Territo M.Monocyte disorders. Merck Manual.Rogalla D, Bomar PA.Listeria monocytogenes. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.Smith HA, Kang Y.The metastasis-promoting roles of tumor-associated immune cells.J Mol Med (Berl). 2013;91(4):411–429. doi:10.1007/s00109-013-1021-5Tadmor T.Monocytes, monocytic myeloid derived suppressor cells and lymphoma: how tight is the knot of the tie?J Leuk(Los Angel) 2013, 1:4. doi:10.4172/2329-6917.1000e103Lin GN, Liu PP, Liu DY, Peng JW, Xiao JJ, Xia ZJ.Prognostic significance of the pre-chemotherapy lymphocyte-to-monocyte ratio in patients with previously untreated metastatic colorectal cancer receiving FOLFOX chemotherapy.Chin J Cancer. 2016;35:5. doi:10.1186/s40880-015-0063-1Knoll, Schultze, Schulte-Schrepping.Monocytes and Macrophages in COVID-19.Frontiers in Immunology. 2021;0. doi:10.3389/fimmu.2021.720109Additional ReadingEigenbrod T, Dalpke AH.Bacterial RNA: An underestimated stimulus for innate immune responses.J Immunol. 2015;195(2):411-8. doi:10.4049/jimmunol.1500530
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Karlmark KR, Tacke F, Dunay IR.Monocytes in health and disease - Minireview.Eur J Microbiol Immunol (Bp). 2012;2(2):97–102. doi:10.1556/EuJMI.2.2012.2.1Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: a systematic approach to a common hematologic finding.Current Hematologic Malignancy Reports. 2021;16(3):267. doi:10.1007/s11899-021-00618-4Patel AA, Yona S.Inherited and environmental factors influence human monocyte heterogeneity.Frontiers in Immunology. 2019;10:2581. doi:10.3389/fimmu.2019.02581Justiz Vaillant AA, Jan A.Physiology, immune response. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.Territo M.Monocyte disorders. Merck Manual.Rogalla D, Bomar PA.Listeria monocytogenes. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.Smith HA, Kang Y.The metastasis-promoting roles of tumor-associated immune cells.J Mol Med (Berl). 2013;91(4):411–429. doi:10.1007/s00109-013-1021-5Tadmor T.Monocytes, monocytic myeloid derived suppressor cells and lymphoma: how tight is the knot of the tie?J Leuk(Los Angel) 2013, 1:4. doi:10.4172/2329-6917.1000e103Lin GN, Liu PP, Liu DY, Peng JW, Xiao JJ, Xia ZJ.Prognostic significance of the pre-chemotherapy lymphocyte-to-monocyte ratio in patients with previously untreated metastatic colorectal cancer receiving FOLFOX chemotherapy.Chin J Cancer. 2016;35:5. doi:10.1186/s40880-015-0063-1Knoll, Schultze, Schulte-Schrepping.Monocytes and Macrophages in COVID-19.Frontiers in Immunology. 2021;0. doi:10.3389/fimmu.2021.720109
Karlmark KR, Tacke F, Dunay IR.Monocytes in health and disease - Minireview.Eur J Microbiol Immunol (Bp). 2012;2(2):97–102. doi:10.1556/EuJMI.2.2012.2.1
Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: a systematic approach to a common hematologic finding.Current Hematologic Malignancy Reports. 2021;16(3):267. doi:10.1007/s11899-021-00618-4
Patel AA, Yona S.Inherited and environmental factors influence human monocyte heterogeneity.Frontiers in Immunology. 2019;10:2581. doi:10.3389/fimmu.2019.02581
Justiz Vaillant AA, Jan A.Physiology, immune response. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.
Territo M.Monocyte disorders. Merck Manual.
Rogalla D, Bomar PA.Listeria monocytogenes. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.
Smith HA, Kang Y.The metastasis-promoting roles of tumor-associated immune cells.J Mol Med (Berl). 2013;91(4):411–429. doi:10.1007/s00109-013-1021-5
Tadmor T.Monocytes, monocytic myeloid derived suppressor cells and lymphoma: how tight is the knot of the tie?J Leuk(Los Angel) 2013, 1:4. doi:10.4172/2329-6917.1000e103
Lin GN, Liu PP, Liu DY, Peng JW, Xiao JJ, Xia ZJ.Prognostic significance of the pre-chemotherapy lymphocyte-to-monocyte ratio in patients with previously untreated metastatic colorectal cancer receiving FOLFOX chemotherapy.Chin J Cancer. 2016;35:5. doi:10.1186/s40880-015-0063-1
Knoll, Schultze, Schulte-Schrepping.Monocytes and Macrophages in COVID-19.Frontiers in Immunology. 2021;0. doi:10.3389/fimmu.2021.720109
Eigenbrod T, Dalpke AH.Bacterial RNA: An underestimated stimulus for innate immune responses.J Immunol. 2015;195(2):411-8. doi:10.4049/jimmunol.1500530
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