Immunopathogenesis of asthma. Exposure to allergen cause synthesis of lgE, which binds to mast cell in airway mucosa On reexposure to allergen, Ag-Ab interaction on mast cell surface triggers release of mediators of anaphylaxis: Histamine, trypase, Prostaglandin D2, leukotriene C4, and platelet-activating factor. These agent provoke contraction of airway smooth muscle, causing immediate fall in FEV1 Reexposure to allergen also causes synthesis and release of cytokines: interleukins 4&5, granulocyte macrophage colony stimulatory factors, tumor necrosis factor and tissue growth factor from Tcells and mast cells. these cytokines attract and activate eosinophil and neutrophils, whose products include eosinophil cationic protein, major basic protein, proteases, and platelet activating factors. These mediators causes edema, mucus hypersecretion, smoothmuscle contraction, and increases in bronchi reactivity associated with late asthmatic response indicated by fall in FEv1 2-8 hrs after exposure Smooth muscle Blood vesse‘ Airway wall : Cell HistaminePGD ECPhis'sarte Proteases I PAF GM-CSF MBP解的PA TNF e的 TGF IgE Mast ce Tlymphocyte ALLERGEN Immunopathogenesis of asthma. Exposure to allergen cause synthesis of IgE, which binds to mast cell in airway mucosa. On reexposure to allergen, Ag-Ab interaction on mast cell surface triggers release of mediators of anaphylaxis: Histamine,trypase, Prostaglandin D2, leukotriene C4, and platelet-activating factor. These agent provoke contraction of airway smooth muscle, causing immediate fall in FEV1. Reexposure to allergen also causes synthesis and release of cytokines: interleukins 4 & 5, granulocyte - macrophage colony stimulatory factors, tumor necrosis factor and tissue growth factor from Tcells and mast cells. These cytokines attract and activate eosinophil and neutrophils, whose products include eosinophil cationic protein, major basic protein, proteases, and platelet activating factors. These mediators causes edema, mucus hypersecretion, smoothmuscle contraction, and increases in bronchial reactivity associated with late asthmatic response indicated by fall in FEV1 2 -8 hrs after exposure