Hypersensitivity Reactions with an Overview on Anaphylaxis
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This document provides an overview of hypersensitivity and anaphylaxis. It begins with objectives and definitions, then discusses Coombs and Gell's classification of hypersensitivity reactions into four types. Type 1 is allergy mediated by IgE, Type 2 involves cytotoxic antibodies, Type 3 involves immune complex formation, and Type 4 is delayed hypersensitivity. It also covers anaphylaxis in detail, including causes, pathophysiology involving mast cell activation, signs and symptoms, diagnosis, treatment, and prevention.
![DIFFERENTIAL DIAGNOSIS
PRESENTATION DIFFERENTIAL DIAGNOSIS
Hypotension Septic shock
Vasovagal reaction
Cardiogenic shock
Hypovolemic shock
Respiratory distress with wheezing or stridor Airway foreign body
Asthma and chronic obstructive pulmonary disease
exacerbation
Vocal chord dysfunction syndrome
Postprandial collapse
Airway foreign body
Monosodium glutamate ingestion
Sulfite ingestion
Scombroid fish poisoning
Flush syndrome
Carcinoid
Postmenopausal hot flushes
Red man syndrome (vancomycin [Vancocin])
Miscellaneous Panic attacks
Systemic mastocytosis
Hereditary angioedema
Leukemia with excess histamine production](https://image.slidesharecdn.com/hypersensitivitylatest-160107183806/85/Hypersensitivity-Reactions-with-an-Overview-on-Anaphylaxis-30-320.jpg)
Hypersensitivity Reactions with an Overview on Anaphylaxis
- 2. OBJECTIVES BRIEF INTRODUCTION ON HYPERSENSIVITY DEFINITION CLASSIFICATION OVERVIEW ON ALL TYPES ANAPHYLAXIS
- 3. BACKGROUND It was coined by Von Pirquet in 1906. Hypersensitivity reactions – ‘over reaction’ of the immune system to harmless environmental antigens or agents like pollens. It occurs when an already sensitized individual is re- exposed to the same foreign substance. Terms hypersensitivity and allergy are used interchangeably
- 4. DEFINITION HYPERSENSITIVITY REACTION A state of altered reactivity in which the body reacts with an exaggerated immune response to a foreign agent. These reactions may be damaging, uncomfortable, or occasionally fatal. Coombs and Gell classified hypersensitivity into 4 types.
- 5. Coombs and Gell’s Classification
- 6. TYPE 1 HYPERSENSITIVITY Commonly called as allergy and can occur within minutes Mediated by IgE antibodies in response to stimulation of Th2 cells by an antigen. The antigens that stimulate it are called allergens (i.e. House dust, Pollens, Cosmetics, Insects, Clothing and Drug) Exposure may be ingested, inhalation, injection or direct contact. Type I hypersensitivity reactions can be systemic (e.g., systemic anaphylaxis) or localized to a specific target tissue or organ (e.g., allergic rhinitis, asthma, Allergic conjunctivitis, urticarial,eczema).
- 7. TYPE II: CYTOTOXIC REACTIONS Body makes special IgG autoantibodies directed against self cells that have some form of foreign protein attached . Hence IgG mediated Antigen: 1. may be intrinsic to the cell membrane 2. may take the form of an exogenous antigen adsorbed on the cell surface. Hypersensitivity results from the binding of antibodies to normal or altered cell-surface antigen Clinical examples include hemolytic anemias, thrombocytopenic purpura, hemolytic transfusion reactions, Goodpasture’s syn drome, and drug-induced hemolytic anemia
- 8. TYPE III: IMMUNE COMPLEX REACTIONS Excess antigens cause immune complexes to form in blood; these circulating complexes usually lodge in small blood vessels Usual sites include kidneys, skin, joints & small blood vessels Lodge in the small vessel walls, trigger inflammation & cause tissue or vessel damage Examples: rheumatoid arthritis, systemic lupus erythematosus & serum sickness
- 9. TYPE IV: DELAYED HYPERSENSITIVITY REACTIONS Reactive cell T-lymphocyte (T-cell) Antibodies & complement not involved Local collection of lymphocytes & macrophages causes edema, induration, ischemia & tissue damage at site within hours to days after exposure Examples: Tb test (positive purified protein derivative), contact dermatitis, poison ivy skin rashes, insect stings, tissue transplant rejection & sarcoidosis
- 11. WHAT IS ANAPHYLAXIS Ana (without), phylaxis (protection). Acute multi-systemic allergic reaction involving the skin, airway, vascular system, and GI. Anaphylaxis is defined as a serious allergic or hypersensitivity reaction (type 1) that is rapid in onset and may cause death.
- 12. HISTORY SPEAKS 1st recorded 2640 BC in hieroglyphics The story of sudden death of a pharaoh after a bee sting Richet & Portier coined term anaphylaxis to describe the unexpected effect during immunization of the dogs.
- 13. The prevalence of anaphylaxis in the general population is at least 1.6% and probably higher - Robert A. Wood, journal of allergy and clinical immunology, 2013. The incidence rate is from 1.21% to 15. 5 % in general population. Neugut, 2001-Arch Int Med Mortality rate -2.4 per million in US. INCEDENCE AND PREVALANCE
- 14. ETIOLOGY Pharmlogic agents • Antibiotics (penicillin) • Nonsteroidal anti-inflammatory drugs (Asprin) • intravenous (IV) contrast agents Stinging insects Physiological • Ants, bees, hornets, wasps. Cold and Exercise induced Food • Peanuts, seafood, and wheat Latex • Rare • No latex-associated deaths
- 15. U.S. TOP “8” •Fish •Crustacean Shellfish •Egg •Milk •Peanuts •Tree-nuts •Soy •Wheat •Gluten ? +Sesame +Molluscs +Sulfites +Gluten Canada Top 8 Plus + Sesame + Molluscs + Sulfites + Gluten + Celery + Mustard + Lupin E.U. Top 8 Plus +Buckwheat + Another 20 allergens are recommended Japan 4 of Top 8 *Milk *Egg *Peanuts *Wheat Plus + Buckwheat +Sesame +Molluscs +Sulfites +Gluten Australia/NZ Top 8 Plus+ Gluten (in place of wheat) + Sulfites Codex Top 7 Plus +Sulfites +Gluten (in place of wheat) Hong Kong Top 7 Plus International Food Allergen List INTERNATIONAL FOOD ALLERGEN LIST
- 16. ETIOLOGY 34% 37% 20% 7% 2% Causes of anaphylaxis in a study of 266 patients (Data from Kemp et al) Food Idiopathic Drugs Exercise Latex, hormones, insect bites
- 17. PATHOPHYSIOLOGY First exposure Activation of TH2 cell → Stimulate IgE switiching Allergen TH2 Cell B Cell
- 18. Pathophysiology First exposure IgE production IgE secreting B cell IgE
- 19. PATHOPHYSIOLOGY First exposure IgE bind to mast cell Mast cell FcɛRI IgE
- 20. PATHOPHYSIOLOGY Second exposure Recognition Allergen Mast cell FcɛRI IgE
- 21. PATHOPHYSIOLOGY Second exposure Activation of mast cell to release histamine and other mediators Allergen Mediators Mast cell FcɛRI IgE
- 22. PATHOPHYSIOLOGY
- 23. SIGNS & SYMPTOMS Itching flushing hives (urticaria) swelling Skin
- 24. SIGNS & SYMPTOMS Itching tearing redness swelling around the eyes Eyes
- 25. SIGNS & SYMPTOMS Sneezing runny nose nasal congestion swelling of the tongue metallic taste Nose & mouth
- 26. SIGNS & SYMPTOMS Difficulty breathing coughing chest tightness wheezing or other sounds increased mucus production throat swelling or itching change in voice or a sensation of choking Lungs and throat
- 27. SIGNS & SYMPTOMS Dizziness weakness fainting rapid, slow, or irregular heart rate low blood pressure Heart and circulation
- 28. SIGNS & SYMPTOMS Nausea vomiting cramps diarrhea Digestive system
- 29. SIGNS & SYMPTOMS Anxiety confusion sense of impending doom Nervous system
- 30. DIFFERENTIAL DIAGNOSIS PRESENTATION DIFFERENTIAL DIAGNOSIS Hypotension Septic shock Vasovagal reaction Cardiogenic shock Hypovolemic shock Respiratory distress with wheezing or stridor Airway foreign body Asthma and chronic obstructive pulmonary disease exacerbation Vocal chord dysfunction syndrome Postprandial collapse Airway foreign body Monosodium glutamate ingestion Sulfite ingestion Scombroid fish poisoning Flush syndrome Carcinoid Postmenopausal hot flushes Red man syndrome (vancomycin [Vancocin]) Miscellaneous Panic attacks Systemic mastocytosis Hereditary angioedema Leukemia with excess histamine production
- 31. An increased amount of tryptase protein can be measured in a blood sample collected during the first three hours after anaphylaxis symptoms have begun. Plasma histamine levels also rises as soon as five to 10 minutes after onset but remain elevated for only 30 to 60 minutes. DIAGNOSTIC CRITERIA naphylaxis network symposium: J Allergy Clin Immunol 2006 ;117 : 391-7 LAB INVESTIGATION
- 33. PREVENTION Avoid the responsible allergen (e.g. food, drug, latex, etc.). Keep an adrenaline kit (e.g. Epipen) and Benadryl on hand at all times. Wear medic Alert bracelets . Venom immunotherapy is highly effective in protecting insect-allergic individuals.
- 34. TREATMENT-FIRST AID Place patient in Trendelenburg position. Establish and maintain airway. Give oxygen via nasal cannula as needed. Place a tourniquet above the reaction site. Epinephrine at the site of antigen injection. Start IV to rise BP.
- 35. TREATMENT OF ANAPHYLAXIS EPINEPHRINE (1:1000) SC or IM- 0.01 mg/kg (maximal dose 0.3-0.5 ml)- administer in a proximal extremity- may repeat every 10-15 min, p.r.n. EPINEPHRINE intravenously (IV)- used for anaphylactic shock not responding to therapy- monitor for cardiac arrhythmias EPINEPHRINE via endotracheal tube Epi-pen shold be kept at work, home Incase of children,it should be kept in school as well.
- 36. TREATMENT OF ANAPHYLAXIS Benadryl (diphenhydramine)- H1 antagonist Tagamet (cimetidine)- H2 antagonist Corticosteroid therapy: hydrocortisone IV or prednisone po
- 37. TREATMENT OF ANAPHYLAXIS Biphasic courses in some cases of anaphylaxis: Recurrence of symptoms: 1-8 hrs later In those with severe anaphylaxis, observe for 6 hours or longer. In milder cases, treat with prednisone; Benadryl every 4 to 6 hours; advise to return immediately for recurrent symptoms
- 38. TREATMENT OF ANAPHYLAXIS IN BETA BLOCKED PATIENTS Give epinephrine initially. If patient does not respond to epinephrine and other usual therapy Glucagon 1 mg IV over 2 minutes
- 39. USE OF EPINEPHRINE IN FOOD ALLERGY Epinephrine should be used immediately after accidental ingestion of foods that have caused anaphylactic reactions in the past. An individual who is allergic to peanut, nuts**, shellfish, and fish should immediately take epinephrine if they consume one of these foods. A mild allergic reaction to other foods (e.g. minor hives,vomiting) may be treated with an antihistamine
- 40. References Abbas & Lichtman, Basic Immunology 3E, Chapter 11 http://www.authorstream.com/Presentation/Moiloa-898248- anaphylaxis/ http://med.mui.ac.ir/clinical/orjanc/Anaphylaxis.ppt http://www.uptodate.com/contents/anaphylaxis-symptoms-and- diagnosis-beyond-the-basics http://www.oregonems.org/Downloads/Anaphylaxis.ppt Anaphylaxis network symposium: J Allergy Clin Immunol 2006 ;117 : 391-7