immune disorders
Overview of Immunodeficiency Disorders
Causes of Immunodeficiency Disorders
Primary immunodeficiency disorders may be caused by mutations, sometimes in a specific gene. If the mutated gene is on the X (sex) chromosome, the resulting disorder is called an X-Linked Inheritance . X-linked disorders occur more often in boys. About 60% of people with primary immunodeficiency disorders are male. Primary immunodeficiency disorders are classified by which part of the Overview of the Immune System is affected: Humoral immunity, which involves B cells (lymphocytes), a type of Cellular immunity, which involves T cells (lymphocytes), a type of white blood cell that helps identify and destroy foreign or abnormal cells Both humoral and cellular immunity (B cells and T cells) Phagocytes (cells that ingest and kill microorganisms) Complement System (proteins that help immune cells kill bacteria and identify foreign cells to destroy) The affected component of the immune system may be missing, reduced in number, or abnormal and malfunctioning. Problems with B cells are the most common primary immunodeficiency disorders, accounting for more than half. These disorders can result from Prolonged (chronic) and/or serious disorders such as diabetes or cancer Drugs Rarely, radiation therapy Immunodeficiency disorders may result from almost any prolonged serious disorder. For example, Diabetes Mellitus (DM) can result in an immunodeficiency disorder because white blood cells do not function well when the blood sugar level is high. Many types of cancer can cause an immunodeficiency disorder. For example, any cancer that affects the bone marrow (such as Overview of Leukemia or Undernutrition —whether of all nutrients or only one—can impair the immune system. When undernutrition causes weight to decrease to less than 80% of recommended weight, the immune system is often impaired. A decrease to less than 70% usually results in severe impairment. Secondary immunodeficiency disorders also occur in older people and people who are hospitalized. Immunosuppressants are drugs used to intentionally suppress the activity of the immune system. For example, some are used to prevent rejection of a transplanted organ or tissue (see table). They may be given to people with an autoimmune disorder to suppress the body's attack against its own tissues. Corticosteroids , a type of immunosuppressant, are used to suppress inflammation due to various disorders, such as rheumatoid arthritis. However, immunosuppressants also suppress the body’s ability to fight infections and perhaps to destroy cancer cells. Chemotherapy and radiation therapy can also suppress the immune system, sometimes leading to immunodeficiency disorders. As people age, the immune system becomes less effective in several ways (see Effects of Aging on the Immune System ). For example, as people age, they produce fewer T cells. T cells help the body recognize and fight foreign or abnormal cells. Undernutrition , which is common among older people, impairs the immune system. Undernutrition is usually thought of as a deficiency of calories, but it may also be a deficiency of one or more essential nutrients. Two nutrients that are particularly important to immunity—calcium and zinc—may be deficient in older people. Certain disorders (such as Diabetes Mellitus (DM) and 