MMI133 Lecture Notes - Lecture 18: Fetus, Contact Dermatitis, Cutaneous Condition

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ultramarineprairie-dog808

21 Jun 2018

School

University of Alberta

Department

Medical Microbiology and Immunology

Course

MMI133

Professor

Judy Gnarpe

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Hypersensitivity

● immune reactions that can cause tissue damage

● all hypersensitivity reactions require previous exposure to the antigen/allergen

4 Main Types

1. Allergy (Type I)

● immediate

● IgE mediated (anaphylactic)

● general anaphylaxis (shock)

● can be localized (hives, urticaria, hay fever, allergic rhinitis) or systemic (shock, requires

epipen such as with peanut allergies)

● systemic reactions occur within minutes, is life threatening due to the blockage of airways,

smooth muscle contractions lead to cramps and unintentional urination/defecation), edema

occurs due to fluid leaking into tissue, and anaphylactic shock (blood pressure drop)

● 3 main events occur

1. Sensitization - classical antigen presentation with T helper cell involvement and B cell

activation (IgE)

2. Activation - cross linking of at least 2 IgE molecules bound to FC receptors on mast cell,

triggers mast cell/basophil degranulation

3. Effector (2 Phases) - primary mediators are released (histamine, eosinophil, chemotactic and

neutrophil factors, proteases) followed by second mediators release (leukotrienes and

prostaglandins)

Mediators Released

Histamine, other lipid molecules and cytokines

1. Increase permeability and dilate blood vessels (edema and erythema/redness)

2. Increase mucus secretion

3. Contract smooth muscle

Treatment of Anaphylaxis

1. Antihistamine - helps to relieve cold symptoms, blocks release of histamine

2. Epinephrine (Epipen) - affects the smooth muscle

2. Cytotoxic/Cell Bound (Type II)

●Transfusion reactions (incorrect blood matching/ABO incompatibilities that lead to cell lysis)

● Antigens attack the antibodies

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Document Summary

Immune reactions that can cause tissue damage. All hypersensitivity reactions require previous exposure to the antigen/allergen. Can be localized (hives, urticaria, hay fever, allergic rhinitis) or systemic (shock, requires. Increase permeability and dilate blood vessels (edema and erythema/redness) Treatment of anaphylaxis: antihistamine - helps to relieve cold symptoms, blocks release of histamine, epinephrine (epipen) - affects the smooth muscle, cytotoxic/cell bound (type ii) Transfusion reactions (incorrect blood matching/abo incompatibilities that lead to cell lysis) Hemolytic disease of the newborn (hdn) - when mother with an rh- factor attacks baby"s. Involves complement and igg or igm (indicates infection in a newborn) antibodies foreign rh+ factor, mother"s antibodies will cause hemolysis in a fetus. Rhogam (anti-rh antibodies) - given before and after delivery, eliminating fetal red blood cells from maternal circulation before b cell activation can occur: immune complex mediated/soluble antigens (type iii) Immune complex (ab-ag) circulate in the blood.