TH2cellssecrete cytokines IL-4, IL-5, IL-13stimulate B cells to produce IgE and otherantibodies. IL-4 stimulates the production of IgE IL-5 activates locally recruited eosinophils IL-13 stimulates mucus secretion frombronchial submucosal glands and alsopromotes IgE production by B cells
Sensitization to Allergen• Inhaled allergens• TH2– dominated response• IgE productions• Eosinophil recruitment• Release of granules and mediators
Allergen-Triggered Asthma• Re-exposure• Ag-induced cross linking of IgE bound to IgEreceptors on mast cell• Mediators released – histamine, leukotrienes• Tight junctions between epithelial cells open• Antigen enter mucosa• Mucosal mast cells activated• Eosinophil release other mediators
• Leukotrienes- constriction of bronchi bronchospasm- increased mucus production mucosalaccumulation• Histamine- increased vascular permeability swelling &redness edema- increased mucus production mucosalaccumulation• Eosinophilic chemotactic factor- Chemotaxis of eosinophils accumulation ofeosinophils
Late Phase• Recruited leukocytesinitiate late phase• Mediators releasefrom endothelium,epithelial cells,leukocytes• Eosinophils MBP,ECP – damageepithelium
Comparison of a normal bronchiolewith that in a patient with asthma• Increase in the number of mucus-secretinggoblet cells in the mucosa and hypertrophy ofsubmucosal mucus glands Accumulation ofmucus in the bronchial lumen• Recruitment of eosinophils & macrophagesintense chronic inflammation• Thickened basement membrane• Hypertrophy & hyperplasia of smooth musclecells
POP-QUIZWhich T Helper Cell plays an importantrole in bronchial asthma?What happens after IgE binds to themast cell in the first phase-sensitizationphase?Leukotrienes causes …?Upon re-exposure of Ag, what happensafter binding of IgE?
Some factors released by eosinophils inthe late phase causes damage to theepithelium. Give 2 examples of thefactors.Give 2 differences of a normalbronchiole and bronchiole of anasthmatic patient.