What Are the Causes of Immunodeficiency?

The immune system is composed of lymphoid tissue, which includes the lymph nodes, tonsils, bone marrow, thymus, parts of the spleen and gastrointestinal tract. It fights off antigens (foreign or abnormal cells) that invade the body. However, when the immune system is deficient, infections are easier to get and harder to fight off. Immunodeficiency (also called immunosuppression) disorders cause a malfunction of the immune system.

Congenital/Primary Immunodeficiency Disorders

• Congenital immunodeficiency disorders are hereditary and are generally present at birth. More than 200 have been described. Immunodeficiency disorders are classified according to which cells are affected. Some disorders have problems with B cells (lymphocytes) and their production of antibodies. Other disorders involve T cells or both B and T cells. Additional disorders arise from problems with complement proteins--complement component 1 (C1) inhibitor deficiency and also with C3, C6, C7 and C8 deficiencies.

Acquired/Secondary Immunodeficiency Disorders

• More commonly, a person with an immunodeficiency disorder has an acquired disorder. Such immunodeficiency disorders develop later in life, often caused by drug (or medication) use. They can also arise as the result of another disorder.

Common Causes for Acquired Immunodeficiency

• Taking medications for a prolonged period can affect the immune system. Medications most likely to damage the immune system are anti-convulsants, immunosuppressants, corticosteroids, chemotherapy drugs and monoclonal antibodies.
  Drugs, in general, destroy the body's defenses. Among the most common drug-related causes are intravenous drug use with dirty needles and other means that spread HIV, which leads to AIDS, the most common and severe acquired immunodeficiency disorder. Other causes include alcoholism, burns and malnutrition.

Additional Causes of Immunodeficiency

• Numerous disorders can lead to immune system malfunction. Blood disorders include aplastic anemia, leukemia, myelofibrosis and sickle cell disease. Cancer (and its treatment) also damages the immune system. Various infections linked with causing immunodeficiency include Epstein-Barr virus infections, HIV, measles, varicella and cytomegalovirus.
  The hormonal disorder diabetes mellitus can also be a cause. A buildup of toxins in the kidneys and nephrotic syndrome can result in an immunodeficiency as can hepatitis of the liver or loss of the spleen. Musculoskeletal disorders, such as lupus and rheumatoid arthritis, might also attack the immune system.
  Most long-term, serious conditions can attribute to immunodeficiency. For example, when blood sugar levels are high for a diabetic, the white blood cells do not function normally; so, maintaining proper blood sugar levels is important for a diabetic.

Treatment

• Your doctor may treat you with immunoglobulin to give you the antibodies your body lacks. When an infection is present, antibiotics will probably be prescribed. Antibiotics may also be prescribed before surgeries to reduce risk of infection. Anti-viral drugs might also be used with immunodeficiency disorders affecting T cells.
  Vaccinations are recommended if the particular disorder does not prevent the production of antibodies; a vaccine of a killed virus (as opposed to live) is generally used.
  Stem cell transplants (obtained from bone marrow usually, but also from blood) may be used in severe cases.