It 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. 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.


A low lymphocyte count alone may not cause any signs or symptoms. The condition usually is found when a person is tested for other diseases or conditions, such as AIDS.

If you have unusual infections, repeat infections, and/or infections that won't go away, your doctor may suspect that you have lymphocytopenia. Fever is the most common symptom of infection.


In general, lymphocytopenia (a low lymphocyte count) occurs because:

  • The body doesn't make enough lymphocytes.
  • The body makes enough lymphocytes, but they're destroyed.
  • The lymphocytes get stuck in the spleen or lymph nodes

A combination of these factors also may cause a low lymphocyte count.

Many diseases, conditions, and factors can lead to a low lymphocyte count. These conditions can be acquired or inherited. "Acquired" means you aren't born with the condition, but you develop it. "Inherited" means your parents passed the gene for the condition on to you.

Exactly how each disease, condition, or factor affects your lymphocyte count isn't known. Some people have low lymphocyte counts with no underlying cause.

Acquired Causes:

Many acquired diseases, conditions, and factors can cause lymphocytopenia. Examples include:

  • Infectious diseases, such as AIDS, viral hepatitis, tuberculosis, and typhoid fever.
  • Autoimmune disorders, such as lupus. (Autoimmune disorders occur if the body's immune system mistakenly attacks the body's cells and tissues.).
  • Steroid therapy.
  • Blood cancer and other blood diseases, such as Hodgkin's disease and aplastic anemia.
  • Radiation and chemotherapy (treatments for cancer).

Inherited Causes:

Certain inherited diseases and conditions can lead to lymphocytopenia. Examples include DiGeorge anomaly, Wiskott-Aldrich syndrome, severe combined immunodeficiency syndrome, and ataxia-telangiectasia. These inherited conditions are rare.


Lymphocytopenia is diagnosed from the results of a complete blood count. In adults, a lymphocyte level below 1,500 cells/microliter is diagnostic (proof of the condition), and in children, a lymphocyte level below 3,000 cells/microliter is diagnostic.


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.


Effective management of granulocytopenia must identify and eliminate the cause and control infection until the bone marrow can generate more leukocytes. In many cases, this means drug or radiation therapy must be stopped and antibiotic treatment begun immediately, even while awaiting test results. Treatment may also include antifungal preparations. Administration of granulocyte colony-stimulating factor (CSF) or granulocyte-macrophage CSF is a newer treatment used to stimulate bone marrow production of neutrophils. Spontaneous restoration of leukocyte production in bone marrow generally occurs within 1 to 3 weeks. Treatment of lymphocytopenia includes eliminating the cause and managing any underlying disorders. For infants with SCID, therapy may include bone marrow transplantation.