White blood cells, representing approximately 1 percent of the blood, provide resistance against infection and disease. Causes of low white blood count include viral infection, cancer, HIV, chronic disorders and chemotherapy, radiation and certain medications.
White Blood Cells
White blood cells are manufactured by the bone marrow and stored in the blood. Living for only a few days, they are capable of swimming through the blood to wherever needed. Their main functions are to fight infection by producing antibodies, destroying bacteria, and ingesting foreign matter and harmful organisms. When an infection is detected, white blood cells swarm to the infected area. White blood cells fall into three groups: lymphocytes, monocytes and granulocytes.
Lymphocytes represent between 20 and 40 percent of white blood cells. Their main function is to identify abnormal cells and foreign substances and destroy them, according to Encyclopedia Britannica. There are two types of lymphocyte cells, T cells and B cells.
There are three sub-types of T cells. There are killer cells that destroy infected cells, cancerous cells and invasive cells. Helper cells assist in the production of antibodies, while regulatory cells keep the immune system under control. B cells recognize invasive microorganisms and produce antibodies to destroy them.
Symptoms of Low White Blood Cell Count and Lymphocytes
In some instances, symptoms of low white cells are so minor as to be unnoticeable, while in other cases a patient's health is noticeably affected, states the Merck Manual on Medical Topics. Although these symptoms are not specific, several, taken together, could indicate this condition. These include a slight fever, aching body, headache and feeling cold for no obvious reason. People with low white cell counts are susceptible to disease and readily infected by viruses, parasites, fungal infections and bacteria.
Primary Causes for Low White Blood Count and Low Lymphocytes Absolute Count
Reasons for low white cell counts vary and may be due to acute or chronic conditions, explains the Merck Manual. Acute illnesses are temporary and white cell counts recover once patients get better. In chronic illness, a different strategy is needed to handle the effects of long-term, hard-to-control illness.
Reasons for acute low white cell counts include short-term viral infections, such as the common cold, flu and hepatitis. They may be caused by certain medications, including prednisone and antibiotics. People who are stressed, suffering from physical exhaustion, not eating healthy balanced diets and anemia may also have low white blood cell counts.
A chronic reduction in white cell counts is caused by long-term diseases and conditions that affect the body's immune systems. These include infections such as HIV/AIDS and tuberculosis as well as liver disease. Cancers that affect the immune system, including leukemia and lymphoma, reduce the white cell count, according to the Mayo Clinic. Chemotherapy or radiation used to treat cancer destroys white blood cells and reduces the ability of the body to produce more. Other illnesses ,such as rheumatoid arthritis and lupus, where the immune system attacks the body, also reduce the white cell count.
Diagnosis of Low White Blood Count
To diagnose low white blood cell or low lymphocyte count, a full blood count is performed. A small sample of blood is taken by a doctor or nurse and sent to a laboratory where the numbers of red and white blood cells, platelets and hemoglobin levels are measured. Depending on age, a normal white blood cell count is between 4,500 and 11,000 cells per cubic millimeter, says Encyclopedia Britannica.