White Blood Cells (WBCs): Types and Function

Table of ContentsView AllTable of ContentsTypesHow They’re FormedSymptoms of WBC DisordersElevated CountsLow WBC Counts

Table of ContentsView All

View All

Table of Contents

Types

How They’re Formed

Symptoms of WBC Disorders

Elevated Counts

Low WBC Counts

White blood cells (WBCs) are a part of your immune system that fight infection and defend the body against other foreign materials.

There are five types of white blood cells:

Each type of white blood cell has a specific job. Some spot intruders and kill harmful bacteria. Others make antibodies to protect your body from bacteria and viruses.

Verywell / Ellen Lindner

Types of WBCs

White blood cells are also known asleukocytes. They are the body’s defense against infections. There are several different types with different purposes.

Some white blood cells are part of our innate immune system, meaning they know how to attack foreigners from the moment we’re born. Other white blood cells are part of our humoral or learned immune system. Humoral immune cells make antibodies after exposure to a germ to help prepare the body for a future attack.

The five types of white blood cells include:

How WBCs Are Formed

White blood cells start out in the bone marrow in a process called hematopoiesis. All blood cells come from a commonhematopoieticstem cell (HSC). These stem cells specialize—or differentiate—in different stages.

The HSC cell first separates into one of two types of stem cells:

A low WBC count does not have symptoms on its own, but having low WBCs can make you more likely to get an infection.

Common symptoms of infections include:

What Is a Normal WBC Count?A normal white blood cell count is usually between 4,000 and 10,000 cells per microliter (mcL).

What Is a Normal WBC Count?

A normal white blood cell count is usually between 4,000 and 10,000 cells per microliter (mcL).

Elevated White Blood Cell Counts

Leukocytosis means ahigh white blood cell count. Infections usually cause a higher-than-normal (elevated) white blood cell count, but there are also other causes of high WBCs.

Common causes of elevated WBCs include:

The treatment for high WBCs depends on what’s causing the levels to be elevated. For example, bacterial infections can cause high white blood cells and can often be treated with antibiotics.

Myeloproliferative Disorders

Myeloproliferativedisorders are a specific group of conditions that can affect blood cells. Some of these conditions can lead to a higher-than-normal white blood cell count, including:

Myelodysplastic Syndrome

Myelodysplasticsyndrome refers to cancers that affect the bone marrow and lead to problems with blood cells. Usually, these cancers cause low blood cell counts but some of them can cause high white blood cell counts.They include:

Medications

Some medications can raise WBC, including:

The rise in WBC might be temporary and go back to normal once these medications are stopped.

Low White Blood Cell Counts

Like with higher-than-normal WBC counts, treating low white blood cell counts depends on what the cause is. It’s also important that people with low WBCs take steps to prevent infections since they are at a higher risk for them.

Mostmyeloproliferativedisorders cause high rather than low WBCs, but primary myelofibrosis can eventually lead to low white blood cell counts because scarring damages the bone marrow.

Low WBCs can also happen when someone is being treated for cancer, so people with chronic myeloid leukemia or other blood cancers can also get low WBCs.

Most myelodysplastic syndromes can cause a decreased WBC count because they damage the bone marrow.Symptoms can include easy bruising and bleeding, fatigue, and fever but in the early stages, people may not have symptoms.

Certain medications and treatments can also lower WBCs, including:

Chemotherapy

One of chemotherapy’s most common and dangerous side effects is its effect on neutrophils. These white blood cells are the first line of defense of the immune system, so not having enough of them while going through cancer treatment (chemotherapy-induced neutropenia) increases a person’s risk for serious infection.

Neutropenia makes it more difficult for the body to fight off infections. As a result, bacteria that are normally not very harmful can cause serious illness. Cancer patients getting radiation treatment can also have low WBCs.

Summary

White blood cells are an important part of our immune system. Different types of white blood cells perform different functions in the body. Overall, white blood cells help to protect us against bacteria, viruses, and parasites.

A high white blood cell countis usually a sign of an infection or illness. A low white blood cell count can indicate another type of problem. Low white blood cell counts can leave you vulnerable to serious infections. Chemotherapy is a common cause of low white blood cell counts.

22 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.Mcbrien CN, Menzies-Gow A.The biology of eosinophils and their role in asthma.Front Med (Lausanne).2017;4:93. doi:10.3389/fmed.2017.00093Cromheecke JL, Nguyen KT, Huston DP.Emerging role of human basophil biology in health and disease.Curr Allergy Asthma Rep.2014;14(1):408. doi:10.1007/s11882-013-0408-2Hoffman W, Lakkis FG, Chalasani G.B cells, antibodies, and more.Clin J Am Soc Nephrol.2016;11(1):137-54. doi:10.2215/CJN.09430915MedlinePlus.Vaccines.Ogle ME, Segar CE, Sridhar S, Botchwey EA.Monocytes and macrophages in tissue repair: Implications for immunoregenerative biomaterial design.Exp Biol Med (Maywood). 2016;241(10):1084-1097. doi:10.1177/1535370216650293Görgens A, Radtke S, Horn PA, Giebel B.New relationships of human hematopoietic lineages facilitate detection of multipotent hematopoietic stem and progenitor cells.Cell Cycle.2013;12(22):3478-82. doi:10.4161/cc.26900Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ.Urinary tract infections: epidemiology, mechanisms of infection and treatment options.Nat Rev Microbiol.2015;13(5):269-84. doi:10.1038/nrmicro3432Hong JW, Noh JH, Kim DJ.Association between White Blood Cell Counts within Normal Range and Hemoglobin A1c in a Korean Population.Endocrinol Metab (Seoul).2018;33(1):79-87. doi:10.3803/EnM.2018.33.1.79Riley LK, Rupert J.Evaluation of patients with leukocytosis.Am Fam Physician.2015;92(11):1004-11.NYC Langone.Types of myeloproliferative disorders.Johns Hopkins.Polycythemia vera.Leukemia and Lymphoma Society.Myeloproliferative neoplasms.NORD.Essential thrombocytopenia.Leukemia and Lymphoma Society.Myelofibrosis.National Cancer Institute.Myelodysplastic syndromes.American Cancer Society.What is chronic myelomonocytic leukemia?.Gotlib J.How I treat atypical chronic myeloid leukemia.Blood. 2017;129(7):838-845. doi:10.1182/blood-2016-08-693630Nemours KidsHealth.Juvenile myelomonocytic leukemia (JMML).MedlinePlus.White blood cell count.American Cancer Society.Chronic myeloid leukemia early detection, diagnosis, and staging.Canadian Cancer Society.Myelodysplastic syndromes.Kasi PM, Grothey A.Chemotherapy-induced neutropenia as a prognostic and predictive marker of outcomes in solid-tumor patients.Drugs. 2018;78(7):737-745. doi:10.1007/s40265-018-0909-3

22 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.Mcbrien CN, Menzies-Gow A.The biology of eosinophils and their role in asthma.Front Med (Lausanne).2017;4:93. doi:10.3389/fmed.2017.00093Cromheecke JL, Nguyen KT, Huston DP.Emerging role of human basophil biology in health and disease.Curr Allergy Asthma Rep.2014;14(1):408. doi:10.1007/s11882-013-0408-2Hoffman W, Lakkis FG, Chalasani G.B cells, antibodies, and more.Clin J Am Soc Nephrol.2016;11(1):137-54. doi:10.2215/CJN.09430915MedlinePlus.Vaccines.Ogle ME, Segar CE, Sridhar S, Botchwey EA.Monocytes and macrophages in tissue repair: Implications for immunoregenerative biomaterial design.Exp Biol Med (Maywood). 2016;241(10):1084-1097. doi:10.1177/1535370216650293Görgens A, Radtke S, Horn PA, Giebel B.New relationships of human hematopoietic lineages facilitate detection of multipotent hematopoietic stem and progenitor cells.Cell Cycle.2013;12(22):3478-82. doi:10.4161/cc.26900Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ.Urinary tract infections: epidemiology, mechanisms of infection and treatment options.Nat Rev Microbiol.2015;13(5):269-84. doi:10.1038/nrmicro3432Hong JW, Noh JH, Kim DJ.Association between White Blood Cell Counts within Normal Range and Hemoglobin A1c in a Korean Population.Endocrinol Metab (Seoul).2018;33(1):79-87. doi:10.3803/EnM.2018.33.1.79Riley LK, Rupert J.Evaluation of patients with leukocytosis.Am Fam Physician.2015;92(11):1004-11.NYC Langone.Types of myeloproliferative disorders.Johns Hopkins.Polycythemia vera.Leukemia and Lymphoma Society.Myeloproliferative neoplasms.NORD.Essential thrombocytopenia.Leukemia and Lymphoma Society.Myelofibrosis.National Cancer Institute.Myelodysplastic syndromes.American Cancer Society.What is chronic myelomonocytic leukemia?.Gotlib J.How I treat atypical chronic myeloid leukemia.Blood. 2017;129(7):838-845. doi:10.1182/blood-2016-08-693630Nemours KidsHealth.Juvenile myelomonocytic leukemia (JMML).MedlinePlus.White blood cell count.American Cancer Society.Chronic myeloid leukemia early detection, diagnosis, and staging.Canadian Cancer Society.Myelodysplastic syndromes.Kasi PM, Grothey A.Chemotherapy-induced neutropenia as a prognostic and predictive marker of outcomes in solid-tumor patients.Drugs. 2018;78(7):737-745. doi:10.1007/s40265-018-0909-3

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.

Mcbrien CN, Menzies-Gow A.The biology of eosinophils and their role in asthma.Front Med (Lausanne).2017;4:93. doi:10.3389/fmed.2017.00093Cromheecke JL, Nguyen KT, Huston DP.Emerging role of human basophil biology in health and disease.Curr Allergy Asthma Rep.2014;14(1):408. doi:10.1007/s11882-013-0408-2Hoffman W, Lakkis FG, Chalasani G.B cells, antibodies, and more.Clin J Am Soc Nephrol.2016;11(1):137-54. doi:10.2215/CJN.09430915MedlinePlus.Vaccines.Ogle ME, Segar CE, Sridhar S, Botchwey EA.Monocytes and macrophages in tissue repair: Implications for immunoregenerative biomaterial design.Exp Biol Med (Maywood). 2016;241(10):1084-1097. doi:10.1177/1535370216650293Görgens A, Radtke S, Horn PA, Giebel B.New relationships of human hematopoietic lineages facilitate detection of multipotent hematopoietic stem and progenitor cells.Cell Cycle.2013;12(22):3478-82. doi:10.4161/cc.26900Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ.Urinary tract infections: epidemiology, mechanisms of infection and treatment options.Nat Rev Microbiol.2015;13(5):269-84. doi:10.1038/nrmicro3432Hong JW, Noh JH, Kim DJ.Association between White Blood Cell Counts within Normal Range and Hemoglobin A1c in a Korean Population.Endocrinol Metab (Seoul).2018;33(1):79-87. doi:10.3803/EnM.2018.33.1.79Riley LK, Rupert J.Evaluation of patients with leukocytosis.Am Fam Physician.2015;92(11):1004-11.NYC Langone.Types of myeloproliferative disorders.Johns Hopkins.Polycythemia vera.Leukemia and Lymphoma Society.Myeloproliferative neoplasms.NORD.Essential thrombocytopenia.Leukemia and Lymphoma Society.Myelofibrosis.National Cancer Institute.Myelodysplastic syndromes.American Cancer Society.What is chronic myelomonocytic leukemia?.Gotlib J.How I treat atypical chronic myeloid leukemia.Blood. 2017;129(7):838-845. doi:10.1182/blood-2016-08-693630Nemours KidsHealth.Juvenile myelomonocytic leukemia (JMML).MedlinePlus.White blood cell count.American Cancer Society.Chronic myeloid leukemia early detection, diagnosis, and staging.Canadian Cancer Society.Myelodysplastic syndromes.Kasi PM, Grothey A.Chemotherapy-induced neutropenia as a prognostic and predictive marker of outcomes in solid-tumor patients.Drugs. 2018;78(7):737-745. doi:10.1007/s40265-018-0909-3

Mcbrien CN, Menzies-Gow A.The biology of eosinophils and their role in asthma.Front Med (Lausanne).2017;4:93. doi:10.3389/fmed.2017.00093

Cromheecke JL, Nguyen KT, Huston DP.Emerging role of human basophil biology in health and disease.Curr Allergy Asthma Rep.2014;14(1):408. doi:10.1007/s11882-013-0408-2

Hoffman W, Lakkis FG, Chalasani G.B cells, antibodies, and more.Clin J Am Soc Nephrol.2016;11(1):137-54. doi:10.2215/CJN.09430915

MedlinePlus.Vaccines.

Ogle ME, Segar CE, Sridhar S, Botchwey EA.Monocytes and macrophages in tissue repair: Implications for immunoregenerative biomaterial design.Exp Biol Med (Maywood). 2016;241(10):1084-1097. doi:10.1177/1535370216650293

Görgens A, Radtke S, Horn PA, Giebel B.New relationships of human hematopoietic lineages facilitate detection of multipotent hematopoietic stem and progenitor cells.Cell Cycle.2013;12(22):3478-82. doi:10.4161/cc.26900

Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ.Urinary tract infections: epidemiology, mechanisms of infection and treatment options.Nat Rev Microbiol.2015;13(5):269-84. doi:10.1038/nrmicro3432

Hong JW, Noh JH, Kim DJ.Association between White Blood Cell Counts within Normal Range and Hemoglobin A1c in a Korean Population.Endocrinol Metab (Seoul).2018;33(1):79-87. doi:10.3803/EnM.2018.33.1.79

Riley LK, Rupert J.Evaluation of patients with leukocytosis.Am Fam Physician.2015;92(11):1004-11.

NYC Langone.Types of myeloproliferative disorders.

Johns Hopkins.Polycythemia vera.

Leukemia and Lymphoma Society.Myeloproliferative neoplasms.

NORD.Essential thrombocytopenia.

Leukemia and Lymphoma Society.Myelofibrosis.

National Cancer Institute.Myelodysplastic syndromes.

American Cancer Society.What is chronic myelomonocytic leukemia?.

Gotlib J.How I treat atypical chronic myeloid leukemia.Blood. 2017;129(7):838-845. doi:10.1182/blood-2016-08-693630

Nemours KidsHealth.Juvenile myelomonocytic leukemia (JMML).

MedlinePlus.White blood cell count.

American Cancer Society.Chronic myeloid leukemia early detection, diagnosis, and staging.

Canadian Cancer Society.Myelodysplastic syndromes.

Kasi PM, Grothey A.Chemotherapy-induced neutropenia as a prognostic and predictive marker of outcomes in solid-tumor patients.Drugs. 2018;78(7):737-745. doi:10.1007/s40265-018-0909-3

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