Immunodeficiency Disorders, Symptoms and Causes
Immune system disorders occur when the immune system does not fight tumors or harmful substances as it should. The immune response may be overactive or underactive.
Immunodeficiency disorders may affect any part of the immune system. Most commonly, such a condition occurs when specialized white blood cells called T or B lymphocytes (or both) do not work as well as they should, or when your body doesn't produce enough antibodies.
Inherited immunodeficiency disorders that affect B cells include:
- Hypogammaglobulinemia, which usually causes respiratory and gastrointestinal infections
- Agammaglobulinemia, which results in frequent severe infections early in life, and is often deadly
Inherited immunodeficiency disorders that affect T cells may cause increased susceptibility to fungi, resulting in recurring Candida (yeast) infections. Inherited combined immunodeficiency affects both T cells and B cells. It may be deadly within the first year of life if it isn't treated early.
People are said to be immunosuppressed when they have an immunodeficiency disorder due to medicines that affect the immune system (such as corticosteroids). Immunosuppression is also a common side effect of chemotherapy given to treat cancer.
Acquired immunodeficiency may be a complication of diseases such as HIV infection and malnutrition (particularly with a lack of protein). Many cancers may also cause immunodeficiency.
People who have had their spleen removed have an acquired immunodeficiency, and are at higher risk for infection by certain bacteria that the spleen would normally help fight. Patients with diabetes are also at higher risk for certain infections.
Increasing age reduces the effectiveness of the immune system to some degree. Immune system tissues (particularly lymphoid tissue such as the thymus) shrink, and the number and activity of white blood cells drop.