Disorders%20of%20the%20Immune%20SystemF10

Disorders%20of%20the%20Immune%20SystemF10 - DISORDERS of...

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DISORDERS of the DISORDERS of the IMMUNE SYSTEM IMMUNE SYSTEM Chapter 19 Chapter 19
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Disorders in the Immune System Disorders in the Immune System Exaggerated or hypersensitivity response Allergic responses to food, pollen, animal dander Drug reactions Transfusion reactions Transplantation rejections Autoimmune diseases – reaction to self Ag Inadequate responses Immune deficiencies
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HYPERSENSITIVITIES HYPERSENSITIVITIES Exaggerated immune response or hyperimmune response ALLERGIC RESPONSE or allergy Allergen = Ag that causes an allergic response Exposure to an allergen causes a person to be sensitized to the allergen Hypersensitivity reaction occurs when a sensitized person is exposed to the allergen
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HYPERSENSITIVITY REACTIONS HYPERSENSITIVITY REACTIONS Type I - Anaphylactic Reactions Type II - Cytotoxic Reactions Type III - Immune Complex Reactions Type IV - Cell-mediated Reactions Types I - III reactions are mediated by Abs Usually occurs immediately <30 min to 12 hours after Ag exposure Type IV reactions are mediated by T cells Usually occurs later i.e. delayed 1-2 days after Ag exposure
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TYPE I (Anaphylactic) Reactions TYPE I (Anaphylactic) Reactions Response occurs within minutes after Ag exposure < 30 minutes Localized or general (systemic) reactions Hay fever, asthma, insect venom, hives, drug reactions MECHANISM: IgE (“reagin”) stably bound to mast cells & basophils Ag binds to 2 adjacent IgE molecules, CROSSLINKING THEM Mast cells & basophils are triggered to degranulate Granules contain preformed mediators Histamine & serotonins Newly formed mediators are also generated Leukotrienes & prostaglandins derived from plasma membrane phospholipids
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The Mechanism of Anaphylaxis The Mechanism of Anaphylaxis Figure 19.1a
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A Degranulated Mast Cell A Degranulated Mast Cell Figure 19.1b
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MEDIATORS of TYPE I (Anaphylactic) MEDIATORS of TYPE I (Anaphylactic) HISTAMINE = vasoactive chemical (amine) that increases capillary permeability EDEMA (swelling) Increased mucus secretion Contraction of smooth muscles LEUKOTRIENES - prolongs the reaction Prolonged smooth muscle contraction PROSTAGLANDINS - also prolongs the reaction Increases mucus secretion Prolongs smooth muscle contractions Mediators function to attract PMNs & eosinophils to site of infection
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LOCALIZED TYPE I REACTIONS LOCALIZED TYPE I REACTIONS INHALANT ALLERGENS Mast cells localized near mucous membranes of respiratory tract are involved Dust, pollens, animal dander etc. INGESTION of ALLERGENS Food allergens interacting with mast cells of intestinal tract Eggs, peanuts, other nuts, milk, soy, fish, wheat & peas ATOPY “out of place” Localized anaphylaxis (an immediate, exaggerated allergic reaction to allergens) that is detrimental to the host
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Figure 19.2a
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SYSTEMIC TYPE I REACTIONS SYSTEMIC TYPE I REACTIONS INJECTION of ALLERGEN Insect stings, drugs
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This note was uploaded on 01/12/2011 for the course BIOL 246 taught by Professor Kocache during the Fall '10 term at George Mason.

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Disorders%20of%20the%20Immune%20SystemF10 - DISORDERS of...

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