Hypersensitivity Lecture Notes PDF

Here's a summary and review of the slides from the study guide to help with your test preparation: Introduction to Hypersensitivity Definition: Exaggerated or inappropriate immune responses to antigens. Four Types of Hypersensitivity: 1. Type I (Immediate): IgE-mediated, fast onset (seconds to...

Here's a summary and review of the slides from the study guide to help with your test preparation: Introduction to Hypersensitivity Definition: Exaggerated or inappropriate immune responses to antigens. Four Types of Hypersensitivity: 1. Type I (Immediate): IgE-mediated, fast onset (seconds to minutes). Examples: anaphylaxis, asthma. 2. Type II (Cytotoxic): IgG or IgM binds to cell surface antigens. Examples: hemolytic anemia, Rh incompatibility. 3. Type III (Immune Complex-Mediated): Antigen-antibody complexes deposit in tissues, causing inflammation. Examples: serum sickness, PSGN. 4. Type IV (Delayed-Type): T-cell-mediated, delayed onset (48--72 hours). Examples: contact dermatitis, tuberculin skin test. Immune Mediators and Mechanisms Type I: IgE triggers mast cells and basophils to release histamine, leukotrienes, and prostaglandins. Type II: IgG/IgM activates complement or phagocytosis to destroy cells. Type III: Immune complexes activate complement and recruit neutrophils. Type IV: T cells release cytokines, activating macrophages. Clinical Manifestations 1. Anaphylaxis (Type I): Symptoms: Hypotension, airway constriction, urticaria. Mediators: Histamine, leukotrienes. Treatment: Epinephrine, antihistamines, corticosteroids. 2. Hemolytic Anemia (Type II): Symptoms: Fatigue, jaundice, pallor, dark urine. Mediators: IgG, IgM, complement. Examples: Rh incompatibility, blood transfusion reactions. 3. Serum Sickness (Type III): Symptoms: Fever, rash, joint pain, swollen lymph nodes. Trigger: Immune complexes from foreign proteins/drugs. 4. Contact Dermatitis (Type IV): Symptoms: Red, itchy, vesicular rash. Trigger: Allergens like poison ivy or nickel. Treatment: Avoid allergens, topical steroids. Key Concepts for Differentiation Mediators: Antibodies (Types I--III), T cells (Type IV). Onset: Immediate (Type I) to delayed (Type IV). Diagnosis and Treatment: Antihistamines: Type I. Steroids: All types. Immunosuppressants: Type IV (e.g., in organ transplants). Biologics: Target specific mediators (e.g., monoclonal antibodies). Cytokines and Complements Cytokines: IL-4 drives IgE production (Type I). TNF-α enhances inflammation (Types II, III). IFN-γ activates macrophages (Type IV). Complement System: Cascade of proteins identifying and destroying pathogens, critical in Types II and III. Test Tips 1. Memorize the immune mediators (IgE for Type I, IgG/IgM for Types II & III, T cells for Type IV). 2. Know examples and symptoms for each hypersensitivity type. 3. Understand the time of onset and specific triggers for each type. 4. Be familiar with therapeutic interventions and their rationale. Let me know if you'd like detailed flashcards or additional clarifications!