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.
Classification
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]
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]
Prognosis
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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^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.
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