Immune System Disorders
Immune system disorders include any of various failures in the body’s defense mechanisms against infectious organisms. Disorders of immunity include immune deficiency diseases, such as AIDS, that arise because of a diminution of some aspect of the immune response. Other types of immune disorders are caused when the body develops an inappropriate response to a substance—either to a normally harmless foreign substance found in the environment, in the case of allergies, or to a component of the body, in the case of autoimmune diseases.
Immune System Disorders Encyclopedia Articles
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allergy
Allergy, hypersensitivity reaction by the body to foreign substances (antigens) that in similar amounts and circumstances are harmless within the bodies of other people. Antigens that provoke an allergic...
leukocytosis
Leukocytosis, abnormally high number of white blood cells (leukocytes) in the blood circulation, defined as more than 10,000 leukocytes per cubic millimetre of blood. Leukocytosis is most commonly the...
leukopenia
Leukopenia, abnormally low number of white blood cells (leukocytes) in the blood circulation, defined as less than 5,000 leukocytes per cubic millimetre of blood. Leukopenia often accompanies certain infections,...
AIDS
AIDS, transmissible disease of the immune system caused by the human immunodeficiency virus (HIV). HIV is a lentivirus (literally meaning “slow virus”; a member of the retrovirus family) that slowly attacks...
Hashimoto disease
Hashimoto disease, a noninfectious form of inflammation of the thyroid gland (thyroiditis). Hashimoto disease is an autoimmune disorder (i.e., the body reacts to its own tissues as though they were foreign...