ALLERGIC REACTIONS Localized Anaphylaxis

ATOPIC DISEASES Localized anaphylaxis (common allergy) ~20% of US population Limited production of IgE and sensitization of mast cells in localized areas Ex: Allergic rhinitis

LATE-PHASE ANAPHYLAXIS Takes several hours for inflammation to show Mast cells release chemotactic factors Eosinophils Neutrophils Helper T Cells

ASTHMA Triggers 2 parts Early response – mast cells in lower respiratory tract Late response – eosinophils and neutrophils Treatments

FOOD ALLERGIES GI tract reaction Hives = wheal and flare

ECZEMA Atopic dermatitis IgE levels elevated Rash and itching Increased eosinophils and helper T cells Allergen unknown

WHY HYPERSENSITIVITY? B cells that produce IgA vs. B cells that produce IgE Atopic individuals have lower levels of IgA Suppressor T lymphocytes stop production of IgE – defective in atopic individuals

ALLERGIES POSITIVE? Sneezing GI contractions Resistance to pathogens Hygiene hypothesis

TREATMENT OF ALLERGIES Desensitization types Tiny but increasing doses of allergens Series of injections of allergens over weeks -- blocking antibodies Monoclonal antibodies – anti-IgE antibodies