Hypersensitivity Reactions PDF

Overview of Hypersensitivity Reactions 1-N A-Allergy B-antiBody UGME Phase 1 – MED 5710 – The...

Overview of Hypersensitivity Reactions 1-N A-Allergy B-antiBody UGME Phase 1 – MED 5710 – The C-Complex Patient Host Defense & Immune D-Delayed hypersens Mediated Disorders ↳Skin allergies + TB Deepak Kaushik, Asst. Prof., Immunology and Infectious Diseases [email protected] https://www.mun.ca/medicine/faculty-and-staff-resources/faculty-a-z/kaushik-deepak.php 1  Lecture objectives/Lecture organization Identify and distinguish the four types of 10892 (Slides 3-5) Hypersensitivity Reactions (Types I - IV) Describe the immunological mechanisms 10893 (Slides 6-15) underlying Type I hypersensitivity reactions Describe the immunological mechanisms and 10894 (Slides 16-21) pathophysiology underlying Hypersensitivity type II reactions Describe the immunological mechanisms and 10895 (slides 22-27) pathophysiology underlying Hypersensitivity type III reactions Describe the immunological mechanisms and 10896 (slides 28-34) pathophysiology underlying Hypersensitivity type IV reactions Slides 37-42 - summary notes 2 10892 Hypersensitivity Reactions (Types I – IV) Hypersensitivity Reactions (HSR) – occur when the normal immune system produces a heightened reaction to an antigen - may be damaging or fatal Gell & Coombs Classification: Types I-IV: I - Allergy/ Anaphylaxis/Atopy II – antiBody bound to a cell or tissue III – immune Complex IV – Delayed hypersensitivity 3  Hypersensitivity Reactions of the Immune System Antibody-mediated Cell-mediated (T-cells & macrophages) Type I - Immediate or IgE Allergies & Anaphylactic Shock Type- IV, also called Delayed-Type Asthma (Allergic Asthma as a case Hypersensitivity (DTH) study) Type II – IgG or IgM antibodies recognizing antigens on cells or tissues Type III – Immune complexes (IgG + soluble antigen) 4  Common to all Hypersensitivity Reactions u An adaptive immune response u Sensitization to the antigen – primary response u Memory (secondary) response - can persist for years u Antigen is a protein ØMay also be a Hapten or a drug but it must be complexed with a protein or have altered the protein. 5  Hypersensitivity Type I Reactions 10893 Describe the immunological mechanisms underlying Type I hypersensitivity reactions Case study – Allergic Asthma 6  Some Definitions Allergy – from the Greek word for altered reactivity Allergen - an antigen (usually innocuous) that stimulates an IgE antibody response and causes an allergic reaction in susceptible individuals. Atopy - from the Greek word atapos meaning out of place, sometimes used to describe allergy or the propensity of some individuals to develop IgE-mediated antibodies to allergens. Approximately 40% of the population in “developed and industrialized” countries are atopic. Allergy has Increased 2 to 3-fold in the last 30 years. Hives (Urticaria) – itchy raised swellings on the body in response to an allergic reaction Asthma – derived from Greek/Latin – means to breathe hard. It’s a chronic respiratory condition, resulting from a hypersensitivity reaction (usually, but not exclusively Type I/allergy) condition. Anaphylaxis –derived from Greek words meaning “without protection”. It is an immediate and exaggerated systemic allergic condition treatment, that in the absence of immediate treatment can result in death. 7 Seasonal Allergic Rhinitis (Hayfever) occur in 20-25% of Canadians Allergic Asthma Bees, wasps yellow-jackets Food allergies affect about 6- 8% of Canadians