Blood Disorders Types and Function of White Blood Cells (WBCs) By Lynne Eldridge, MD facebook Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time." Learn about our editorial process Lynne Eldridge, MD Medically reviewed by Medically reviewed by Doru Paul, MD on November 17, 2020 Doru Paul, MD, is triple board-certified in medical oncology, hematology, and internal medicine. He is an associate professor of clinical medicine at Weill Cornell Medical College and attending physician in the Department of Hematology Oncology at the New York Presbyterian Weill Cornell Medical Center. Learn about our Medical Review Board Doru Paul, MD on November 17, 2020 Print Table of Contents View All Table of Contents Types of WBC Formation Elevated White Blood Cell Counts Low White Blood Cell Counts White blood cells (WBCs) are a part of the immune system that helps fight infection and defend the body against other foreign materials. Different types of white blood cells are involved in recognizing intruders, killing harmful bacteria, and creating antibodies to protect your body against future exposure to some bacteria and viruses. Types of WBC There are several different types of white blood cells. They are also known as leukocytes. Ellen Lindner / Verywell Neutrophils Neutrophils make up roughly half of the white blood cell population. They are usually the first cells of the immune system to respond to an invader such as a bacteria or a virus. As first responders, they also send out signals alerting other cells in the immune system to respond to the scene. You may be familiar with the appearance of neutrophils as they are the primary cells present in pus. Once released from the bone marrow these cells live for only around eight hours, but around 100 billion of these cells are produced by your body every day. Eosinophils Eosinophils also play a role in fighting off bacteria and are very important in responding to infections with parasites (such as worms). They are perhaps best known for their role in producing allergy symptoms when they go overboard in mounting an immune response against something (like pollen) which is mistakenly believed to be an invader. These cells account for no more than 5% of the white blood cells in your bloodstream but are present in high concentrations in the digestive tract. Basophils Basophils, accounting for only around 1% of white blood cells, are important in mounting a non-specific immune response to pathogens. These cells are perhaps best known for their role in asthma. When stimulated these cells release histamine among other chemicals. The products can result in inflammation and bronchoconstriction in the airways. Lymphocytes (B and T) Lymphocytes are also very important in the immune system, with T cells being responsible for directly killing many foreign invaders. B lymphocytes (B cells), in contrast to the other types of white blood cells, are responsible for humoral immunity (in contrast to the non-specific immunity of other white blood cells). They produce the antibodies that "remember" an infection and stand ready in case your body should be exposed. B lymphocytes play the main role in the efficacy of the majority of the current vaccines but in some cases (i.e. tuberculosis and pertussis vaccines). T lymphocytes are also very important. Monocytes Monocytes are the garbage trucks of the immune system. Around 5% to 12% of white blood cells in your bloodstream are monocytes, but their most important function is to migrate into tissues and clean up dead cells (among other functions.) Formation White blood cells begin in the bone marrow in a process called hematopoiesis. All blood cells, including white blood cells, red blood cells, and platelets, descend from a common hematopoietic stem cell, or "pluripotent" stem cell. These stem cells evolve (differentiate) in different stages. The HSC cell first separates into the lymphoid cell line, via a lymphoid stem or progenitor cell and into the myeloid cell line, via myeloid stem or progenitor cell. The lymphoid stem or progenitor cell gives rise to lymphocytes specifically B lymphocytes or "B cells" and T lymphocytes (T cells). The myeloid stem or progenitor cells give rise to myeloblasts, which further differentiate into macrophages, monocytes, neutrophils, basophils, and eosinophils and into the precursors of red cells and platelets. Lab Values A normal white blood cell count is usually between 4,000 and 10,000 cells per microliter (mcL). Elevated White Blood Cell Counts Though you may think of infections, there are many causes of an elevated white blood cell count. These can be increased by overproduction, or rather by the body releasing white blood cells early from the bone marrow. Stress of any form can also result in this release of white blood cells. Some causes of an increased white blood cell count include: InfectionsCancers such as leukemias, lymphomas, and myelomas in which a greater number of white blood cells are manufacturedInflammation such as inflammatory bowel disease and autoimmune disordersTrauma ranging from fractures to emotional stressPregnancyAsthma and allergiesExercise In severe infections, young-appearing white blood cells, called blasts, often appear in the blood due to the body's attempt to get as many white blood cells on the scene as quickly as possible. Low White Blood Cell Counts Conditions which may result in a low white blood cell count include: Severe infectionsBone marrow damage or disorders including aplastic anemia, bone marrow "takeover" by blood cancers or metastatic cancer, or drug or chemical-related damage to the bone marrowAutoimmune diseases such as lupusSplenic "sequestration" where white blood cells are accumulated in the spleen. Symptoms The symptoms of a low white blood count can be understood by knowing the function of white blood cells. White blood cells are the body's defense against infections. Some of the cells are part of our innate immune system, meaning they know from birth to attack foreigners, and others are part of our humoral, or learned immune system, and manufacturer antibodies after "seeing" a germ in order to be prepared for another attack by that germ ahead of time. Symptoms of infection may include: FeverCoughPain or frequency of urinationBlood in the stoolsDiarrheaRedness, swelling, or warmth in a region of infection Chemotherapy One of the most common and dangerous side effects of chemotherapy is due to its effect on white blood cells, particularly the type of white blood cells known as neutrophils. Neutrophils are essentially the "first responders" of our immune system. A decrease in neutrophils during chemotherapy, known as chemotherapy-induced neutropenia, carries the risk of serious infection. Not only is it more difficult for the body to fight off infections relative to someone without neutropenia, but bacteria which are normally not terribly harmful can cause serious infections. A Word From Verywell From infection to cancers, white blood cells are involved in many functions in the body. These cells may also become diseased themselves. A deficiency of one type of all white blood cells may occur with several immunodeficiency syndromes. A surplus of a type of these cells (due to malignancy) is present in certain disorders, such as leukemias and lymphomas. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Mayadas TN, Cullere X, Lowell CA. The multifaceted functions of neutrophils. Annu Rev Pathol. 2014;9:181-218. doi:10.1146/annurev-pathol-020712-164023 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 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 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 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. 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 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 Additional Reading U.S. Library of Medicine. MedlinePlus. White Blood Cell Count. https://medlineplus.gov/ency/article/003643.htm