Lymphocytes are a sub-class of leukocytes, or white blood cells
, which carry out essential functions in the body's defense system against microorganisms responsible for infection. If the lymphocyte count falls, it is called lymphocytopenia. This condition leads to immunocompromise and can result in diseases of the blood, such as leukemia
or even viral infections like AIDS
. Some forms of cancer
are also responsible for decreased lymphocyte count. Lymphocytopenia can also be cause by natural immune deficiency
, or a weakened immunity due to certain medicinal drugs such as immunosuppressors, corticosteroids, or with the administration of chemotherapy
used to treat cancer.