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  • Disease

    Agammaglobulinemia

    Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

    Agammaglobulinemia is a disorder passed down through families in which a person has very low levels of protective immune system proteins called...

  • Injury

    Allergic reactions

    Dermatographism is a condition where lightly scratching the skin raises wheals or welts. Histamine is released, which causes the small blood vessels (capillaries) to dilate, producing redness and localized swelling.

    Allergic reactions are sensitivities to substances called allergens that come into contact with the skin, nose, eyes, respiratory tract, and gastrointestinal...

  • Disease

    Allergic rhinitis

    Allergic rhinitis, or hay fever, is a collection of symptoms, predominantly in the nose and eyes, to allergens such as dust, dander and pollen. The sensitized immune system produces antibodies to these allergens, which cause chemicals called histamines to be released into the bloodstream, causing itching, swelling of affected tissues, mucus production, hives, rashes, and other symptoms. Symptoms vary in severity from person to person.

    Allergic rhinitis is a diagnosis associated with a group of symptoms affecting the nose. These symptoms occur when you breathe in something you are allergic...

  • Disease

    Allergies

    Hives (urticaria) are raised, red, itchy welts, seen here on the arm.  The majority of urticaria develop as a result of allergic reactions.  Occasionally, they may be associated with autoimmune diseases, infections (parasitosis), drugs,  malignancy, or other causes.

    An allergy is an immune response or reaction to substances that are usually not harmful.

  • Test

    Allergy testing - skin

    Intradermal allergy testing is another method of skin testing to help determine whether an individual is allergic to a specific allergen. The test involves injection of a small amount of the suspected allergen under the surface of the skin. After about 20 minutes the area is examined for a reaction at the site. A typical reaction looks like a small hive with swelling and redness. The intradermal test is more sensitive than the skin prick test and can usually provide more consistent results.

    Allergy skin tests are tests used to find out which substances cause a person to have an allergic reaction.

  • Disease

    Anaphylaxis

    Shock is a severe condition that occurs when not enough blood flows through the body, causing very low blood pressure, a lack of urine, and cell and tissue damage.

    Anaphylaxis is a life-threatening type of allergic reaction.

  • Disease

    Angioedema

    Angioedema is swelling that is similar to hives, but the swelling is under the skin instead of on the surface. Hives are often called welts. They are a...

  • Test

    Anti-smooth muscle antibody

    Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

    Anti-smooth muscle antibody is a blood test that detects the presence of antibodies against smooth muscle.

  • Test

    Antibody titer

    The antibody level in the blood is a reflection of the body's past experience or exposure to an antigen, or something that the body does not recognize as self. Every living cell has different protein markers on its surface called antigens, and the body's immune system identifies those cells that are not part of its structure by those surface proteins.

    Antibody titer is a laboratory test that measures the level of antibodies in a blood sample.

  • Test

    Antimitochondrial antibody

    Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

    Antimitochondrial antibodies (AMA) are substances (antibodies) that form against mitochondria, an important part of cells. Mitochondria are the energy source...