Blood Disorders What Is Lymphopenia? By Charles Daniel Charles Daniel Charles Daniel, MPH, CHES is an infectious disease epidemiologist, specializing in hepatitis. Learn about our editorial process Updated on March 31, 2020 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Jason DelCollo, DO Medically reviewed by Jason DelCollo, DO Jason DelCollo, DO, board-certified in family medicine. He is associate faculty at Philadelphia College of Osteopathic Medicine as well as adjunct faculty with the Crozer Family Medicine Residency Program, and is an attending physician at Glen Mills Family Medicine in Glen Mills, Pennsylvania. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Lymphocytes Causes Related Conditions Low WBC Count Lymphopenia (also known as lymphocytopenia) is a term used to describe the state where you have a reduced level of a certain type of blood cell called a lymphocyte. Lymphocytes are one of three types of white blood cells (WBC), also known as leukocytes, found in the blood. Leukocytes function as part of our body’s first-line immune defense against disease-causing pathogens such as bacteria, viruses, and parasites. Lymphopenia is most often caused by infection, including the flu, and will usually recover on its own once the infection has cleared. In cases where the cause is idiopathic (of unknown origin), it may suggest a more serious underlying condition. Andrew Brookes / Getty Images Lymphocytes The vast majority of cells in our blood are erythrocytes (red blood cells) which are responsible for transporting oxygen throughout the body. This is followed by thrombocytes (platelets) and leukocytes. Leukocytes are produced in the bone marrow and circulate freely in the bloodstream as part of the immune system. Lymphocytes represent the largest proportion of these cells, ranging anywhere from 20% and 40%. Lymphocytes can be further broken down into three subsets: Natural killer (NK) cells serve as the first line of defense for the immune system. T cells are produced in response to a specific pathogen. B cells produce antibodies that help other cells identify and neutralize pathogens. Lymphopenia may be identified by the type of lymphocyte affected. For example, HIV specifically targets CD4 T cells for infection, resulting in massive losses of that specific cell. The loss of B cells is more associated with immune-suppressive drugs (such as those used for organ recipients) while NK depletion is typically a rare situation. Causes Lymphopenia can be caused by many conditions, including infection and medication side effects. At times, the condition may only affect lymphocytes. In others, it can be the result of a depletion of all white blood cells. For instance, when the treatment for viral hepatitis includes peginterferon and ribavirin, it can cause suppression of just neutrophils (neutropenia) or just lymphocyte (lymphopenia) in some people. In others, it can affect the entire range of white blood cells (leukopenia). Lymphopenia is most associated with conditions that affect the bone marrow, including: Viral infections that temporarily disrupt bone marrow functionCongenital disorders that involve diminished bone marrow functionCancer or other diseases that damage bone marrowAutoimmune disorders that destroy white blood cells or bone marrow cellsAcute infections that kill off white blood cells faster than they can be producedMedications, such as antibiotics, that can destroy white blood cells Related Conditions The diseases and conditions most commonly associated with lymphopenia can broadly be described as either being pathogenic (related to infection), cytotoxic (toxic to cells), congenital (caused by genetic defect), or nutritional. They include: Aplastic anemia: A rare condition where the body stops producing blood cells Chemotherapy HIV Hypersplenism: The premature destruction of blood cells by the spleen Leukemia: A type of blood cancer Lupus: An autoimmune disorder Malnutrition and vitamin deficiencies Myelodysplastic syndromes: A group of disorders which disrupt the production of blood cells Rheumatoid arthritis: Another autoimmune disorder Radiation therapy Tuberculosis Low White Blood Cell Count An overall low white blood cell count (leukopenia) is most often detected when your healthcare provider orders a test for a condition you're already experiencing. A low count is rarely an unexpected finding. In some cases, the type of white blood cell affected may be enough to point you in the direction of a diagnosis. At other times, you may need additional tests to piece together a cause. A severely low white blood cell count makes places you at greater risk of infection. If your white blood cell count is very low, you may need to take special precautions to prevent illness. This includes avoiding others who may be ill, washing your hands regularly and thoroughly, or even wearing a face mask if you are in a confined space (such as an airplane) with others. 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 7 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. National Cancer Institute. Leukocyte. Territo M. Lymphocytopenia. Merck Manual Professional Version. Kenilworth, NJ: Merck & Co., Inc.; 2019. National Cancer Institute. Seer Training Modules. Composition of the blood. Hartono C, Muthukumar T, Suthanthiran M. Immunosuppressive drug therapy.Cold Spring Harb Perspect Med. 2013;3:a015487 doi:10.1101/cshperspect.a015487 Naeim F, Rao PN, Grody WW. Atlas of Hematopathology: Morphology, Immunophenotype, Cytogenetics, and Molecular Approaches. London, UK: Elsevier Health Science; 2013. Kliegman RM, St. Geme J. Nelson Textbook of Pediatrics. London, UK: Elsevier Health Sciences; 2019. Cleveland Clinic. Low white blood cell count: possible causes. Additional Reading Janeway, C.; Travers, P.; Walport, M.; et al. Immunobiology (5th ed.) New York and London: Garland Science; ISBN 0-8153-4102-6. Regent, A.; Autran, B.; Carcelain, G.; et al. “Idiopathic CD4 lymphocytopenia: clinical and immunologic characteristics and follow-up of 40 patients.” Medicine. 2014; 93(2):61-72.