Immune system


A complex system that is responsible for distinguishing a person from everything foreign to him or her and for protecting his or her body against infections and foreign substances.

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  • Immune thrombocytopenic purpura

    purplish areas in the skin and mucous membranes (such as the mouth lining) where bleeding has occurred as a result of decreased platelets. Immune thrombocytopenic purpura (ITP) can be triggered by drugs, or associated with infection, pregnancy, or immune disorders such as systemic lupus erythematosus. About half of all cases are classified as “idiopathic,” meaning […]

  • Immune tolerance

    Prior contact with the same antigen in fetal life or in the newborn period when the immune system is not yet mature; Prior contact with the antigen in extremely high or low doses; Exposure to radiation, chemotherapy drugs, or other agents that impair the immune system; Heritable diseases of the immune system; Acquired diseases of […]

  • Immunity

    The condition of being immune. Immunity can be innate’for example, humans are innately immune to canine distemper’or conferred by a previous infection or immunization.

  • Immunity, active

    The production of antibodies against a specific agent by the immune system. Active immunity can be acquired in two ways, by contracting an infectious disease such as chickenpox or by receiving a vaccination such as against chickenpox. Active immunity is usually permanent. The individual is protected from the disease all their life. Active immunity is […]

  • Immunization

    Vaccination. Immunizations work by stimulating the immune system, the natural disease-fighting system of the body. The healthy immune system is able to recognize invading bacteria and viruses and produce substances (antibodies) to destroy or disable them. Immunizations prepare the immune system to ward off a disease. To immunize against viral diseases, the virus used in […]


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