Causes of a low lymphocyte count include autoimmune disorders, blood diseases, infections, and treatment with steroids, radiation or chemotherapy drugs, states the National Heart, Lung, and Blood Institute. The medical term for a low lymphocyte count is lymphocytopenia.
Some genetic disorders cause a low lymphocyte count, reports the NHLBI. Ataxia-telangiectasia, Wiskott-Aldrich syndrome and DiGeorge anomaly are three inherited conditions associated with lymphocytopenia. A low lymphocyte count has three general causes: the body produces an inadequate supply of lymphocytes; there are enough lymphocytes, but they are destroyed quickly; or the lymphocytes get trapped in the spleen or liver instead of circulating in the bloodstream.
Infections linked with lymphocytopenia include human immunodeficiency virus, typhoid fever, tuberculosis and hepatitis, notes the NHLBI. Aplastic anemia, Hodgkin's disease and lupus also cause lymphocytopenia.
Lymphocytes are a type of white blood cell used to fight infection, explains KidsHealth. B lymphocytes identify harmful organisms. Once the B cells identify foreign substances, T lymphocytes destroy the invaders. Without these helpful cells, a person is more likely to have chronic infections.
People with lymphocytopenia should take several steps to avoid getting sick, notes NHLBI. Washing the hands frequently, staying away from people who are sick, receiving regular dental care, and getting vaccines for pneumonia and influenza help reduce the risk of infection.