Immediate Hypersensitivity

Immediate Hypersensitivity - BIO/MI 494 Immediate...

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Unformatted text preview: BIO/MI 494 Immediate Hypersensitivity Fall 2008 I. Type of hypersensitivity reactions 1. Type I 2. Type II 3. Type III 4. Type IV II. Immediate hypersensitivity (Type I) overview 1. General features 2. Definition of allergen 3. Biology and synthesis of IgE a. Class switching to IgE 4. Mast cell activation III. The immediate IgE-initiated response in skin 1. Mechanism IV. Regulation of IgE synthesis 1. Heredity (genetic factors) 2. Natural history of antigen exposure 3. Nature of antigen (allergen 4. Hygiene hypothesis V. Effector mechanisms in allergic reactions 1. Fc receptors for IgE-binding to effector cells 2. Biology of mast cells, basophilis and eosinophils 3. Activation of mast cells, basophils and eosinophils VI. Mast cells, basophil and eosinophil derived mediators 1. Biogenic amines 2. Granule proteins 3. Lipid mediators 4. Cytokines VII. Clinical allergy in humans 1. Allergic rhinitis 2. Urticaria and eczema 3. Food allergies 4. Bronchial asthma 5. Anaphylaxis VIII. The Protective role of IgE 1. Eradication of parasites · , Table 1...1. CIassIflaUon of Jmmunologlc DIsusa Typeof . PathOIO~IC Immune Mechanisms of tissue hypersensitivity mechansms Injury and disease . Imme<flate hypersensitivity: Type I IgE antibody . Mast cells and lhelr mediators (vasoacllve amInes, lipid mediators, cytoklnes) Antibody mediated: Type II 19M, IgG antibodies against eea surface or extracellular matrlx antigens Opsoc IlzalIon and p/lagocytosb of cans = and Fe receptor- ad reauItmenI and actIvalion of leukocytes . (neutrophIIs, macrophages) AbnorrnaiIIes In cellular funcIIoos, e.g., hormone receptor signaling Immune complex mediated: Type III Imrnooe complexes of circulating antigens and IgM or JgG antllxxfl6S CompIemeot. and Fe receptor- mediated reaultment and activallon of leukocytes T cell mediated: Type IV 1. C04+ T ceI~ed- type hype . ) 2. coo+ ens (T cell- mediated cytolysis) 1. Macrophage activation, cytokIOe-rrie<flatad InIlammaIion 2. DIrect ~ eea JdIIIng, cytokine- mediated flarnmatlon i./ -<:fr Allergen Airway lumen •• • 1;~~ ••.• 4\ Source EPithelial' • IGc.o05'J_...... ...I:'!:Q,.~~!>..olf<,.;,~,.o6l'!d!ll ~* cell Alle~-~ Migration of d_e_n_d_ri_lic_ce_I_ls and processing :. Allergen-non· by dendritic cells specific IgE Airway smooth muscle Figure 11 Sensitization to allergens in the airway. Allergen can be sampled by dendritic cells in the airway lumen. and can enter tissues through disrupted epithelium (not shown) or, for some allergens with protease activity, can gain access to submucosal dendritic ceUs by cleaving epithelial- cell tight junctions. Activated dendritic ceUs mature and migrate to regional lymph nodes or to sites in the local mucosa, where they present peptides derived from the processed allergen in the context of major histocompatibility complex (MHC) class" molecules to naive T ceUs. In the presence of 'early interleultin 4' (IL-4) (potentially derived from a range of cells, including basophils, mast ceU.s, eosinophils, natural kiUer T ceUs and cells, including basophils, mast ceU....
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Immediate Hypersensitivity - BIO/MI 494 Immediate...

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