Lymphocytopenia is the condition of having an abnormally low level of lymphocytes in the blood. Lymphocytes are a white blood cell with important functions in the immune system. It is also called lymphopenia.[1] The opposite is lymphocytosis, which refers to an excessive level of lymphocytes.
Lymphocytopenia may be present as part of a pancytopenia, when the total numbers of all types of blood cells are reduced.
Classificationedit
In some cases, lymphocytopenia can be further classified according to which kind of lymphocytes are reduced. If all three kinds of lymphocytes are suppressed, then the term is used without further qualification.
In T lymphocytopenia, there are too few T lymphocytes, but normal numbers of other lymphocytes. It causes, and manifests as, a T cell deficiency. This is usually caused by HIV infection (resulting in AIDS), but may be Idiopathic CD4+ lymphocytopenia (ICL), which is a very rare heterogeneous disorder defined by CD4+ T-cell counts below 300 cells/μL in the absence of any known immune deficiency condition, such as human immunodeficiency virus (HIV) infection or chemotherapy.[2]
In B lymphocytopenia, there are too few B lymphocytes, but possibly normal numbers of other lymphocytes. It causes, and manifests as, a humoral immune deficiency. This is usually caused by medications that suppress the immune system.[citation needed]
In NK lymphocytopenia, there are too few natural killer cells, but normal numbers of other lymphocytes. This is very rare.[citation needed]
Causesedit
The most common cause of temporary lymphocytopenia is a recent infection, such as the common cold.[citation needed]
Lymphocytopenia is a frequent, temporary result from many types of chemotherapy, such as with cytotoxic agents or immunosuppressive drugs. Some malignancies that have spread to involve the bone marrow, such as leukemia or advanced Hodgkin's disease,[8][9] also cause lymphocytopenia.
Lymphocytopenia is diagnosed when the complete blood count shows a lymphocyte count lower than the age-appropriate reference interval (for example, below 1.0 x 10(9)/L in an adult).[citation needed]
Prognosisedit
Lymphocytopenia that is caused by infections tends to resolve once the infection has cleared. Patients with idiopathic CD4+ lymphocytopenia may have either abnormally low but stable CD4+ cell counts, or abnormally low and progressively falling CD4+ cell counts; the latter condition is terminal.[citation needed]
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^Ng WL, Chu CM, Wu AK, Cheng VC, Yuen KY (January 2006). "Lymphopenia at presentation is associated with increased risk of infections in patients with systemic lupus erythematosus". QJM. 99 (1): 37–47. doi:10.1093/qjmed/hci155. PMID 16371405.
^Lymphocytopenia from the Merck Manual Home Health Handbook
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^Faguet GB (October 1975). "Quantitation of immunocompetence in Hodgkin's disease". The Journal of Clinical Investigation. 56 (4): 951–7. doi:10.1172/JCI108175. PMC301951. PMID 1159096.
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^Merekoulias G, Alexopoulos EC, Belezos T, Panagiotopoulou E, Jelastopulu DM (March 2010). "Lymphocyte to monocyte ratio as a screening tool for influenza". PLOS Currents. 2: RRN1154. doi:10.1371/currents.rrn1154. PMC2847387. PMID 20383263.
^Over 1,000 Deaths from H1N1 Outbreak in Brazil Archived 2016-09-11 at the Wayback Machine (article from 12 July 2016)
^Low, Donald (2004). "Sars: Lessons from Toronto". Learning from SARS: Preparing for the Next Disease Outbreak: Workshop Summary. National Academies Press (US). pp. 63–71.
^Guan, Wei-jie (February 28, 2020). "Clinical Characteristics of Coronavirus Disease 2019 in China". The New England Journal of Medicine. 382 (18): 1708–1720. doi:10.1056/NEJMoa2002032. PMC7092819. PMID 32109013.
^Venkatesulu BP, Mallick S, Lin SH, Krishnan S (Mar 2018). "A systematic review of the influence of radiation-induced lymphopenia on survival outcomes in solid tumors". Critical Reviews in Oncology/Hematology. 123: 42–51. doi:10.1016/j.critrevonc.2018.01.003. PMID 29482778.
^"The Science Behind LTCI | Treatment for Cats with FIV and FeLV". Archived from the original on 2013-07-02. Retrieved 2013-03-20.