Hypersensitivity Flashcards by Jacob Lucas

what is hypersensitivity

NORMAL immune response that is:

Inappropriately triggered
OR
Excessive
OR
Produces undesirable effects on the body

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what are the basic triggers for hypersensitivity

A specific antigen-antibody reaction

A specific antigen-lymphocyte interaction

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What are the four types of hypersensitivity

Types I, II, III = mediated by ANTIBODIES produced by B cells
Specifically PLASMA cells

Type IV = mediated by T cells (LONGER)

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What is Type 1 hypersensitivity

IgE mediated reaction

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Type 1 key charactersitics

Immediate reaction! (15-20 minutes)

This reaction occurs after being sensitized to an antigen

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Antigens for Type 1 hypersensitivity

Environmental (pet dander, bee stings)
Foods (nuts, seafood, eggs)
Medications (penicillin, contrast dye)

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Etiology of type 1

1 parent allergic = 30% chance
2 parents allergic = 50% chance

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key cells involved in type 1

B lymphocytes
IgE (antibody)
Mast cells (granulocyte)

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What happens when a person is first exposed to allergen

B Cell goes from immature to mature

B cell triggered

B cell transforms to plasma cell and produces antibodies

attaches to mast cells to release chemical mediators which cause reactions

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Potent vasodilation
causes

Stuffy nose
Lower blood pressure
Wheals on skin

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increased vascular permeability causes

edema
runny nose

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Bronchial smooth muscle constriction causes

breathing difficulties
wheezing

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Stimulates irritant receptors
causes

Itching (pruritis)

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Atopic reactions =

inherited tendency to become sensitive to allergens

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Examples of atopic reactions

Allergic rhinitis
Asthma
Urticaria (hives)

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What are the most common triggers of atopic reactions? (4)

Pollen,
dusts,
molds,
animal dander

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What is Type I: Anaphylaxis (Systemic)

systemic release of CHEMICAL MEDIATORS

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Warnings about Anaphylaxis

Life-threatening– 
Bronchial constriction 
Airway obstruction 
Vascular collapse (shock)

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Common triggers of anaphylaxis

medications
bee stings
foods

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What is Type 2 hypersensitivity

Cytotoxic reaction

“WRONG BLOOD”

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Etiology of Type 2

Exposure to antigen or foreign tissue/cells

Antigens are located on cell surface

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Key characteristics of type 2

Antigens stimulate antibody production

Antibodies recognize and attach to cell surface antigens

Direct destruction of targeted cells that contain the antigen

Cell lysis
Phagocytosis

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Immune cells involved in type 2

Study These Flashcards

Antibodies (IgG & IgM)
Complement
WBC’s (phagocytes)

Examples of antigens in type 2

Study These Flashcards

Blood

Some of your body’s own cells (with auto-immune conditions such as Diabetes)

Erythroblastosis fetalis

type 2 example disorders

Blood Transfusion Reaction Newborn/mother Rh incompatibility Autoimmune disorders Hemolytic anemia Myasthenia Gravis Graves disease Certain drug reactions

type 2 manifestation transfusion reaction

Fever, chills, flushing ↑ HR, ↓ BP Chest pain or back pain N/V Restlessness, anxiety Headache

what is type 3 hypersensitivity

Immune Complex Reaction

type 3 key characteristics

Antigen-antibody COMPLEXES form These are deposited into tissues Inflammatory response causes tissue damage

etiology of type 3

Autoimmune attack (or) Low grade infection (or) Inhaled antigens from molds or contaminated plants

possible offending antigens in Type 3

Your body’s own tissues and/or DNA Inhaled antigens from mold or contaminated plants Bacteria or viruses

Key immune cells involved in Type 3

Antibodies (IgG and IgM) that clump with antigens Complement Neutrophils and mast cells

Type 3 Clincial manifestations

Depend on WHERE the complexes are deposited in the tissue! Rheumatoid arthritis- Primarily the joints Glomerulonephritis- kidney failure Systemic lupus erythematosus- Skin and many organs

Difference between Type 2 and Type 3

Type II- reactions occur on the cell surface and result in direct cell death or malfunction Type III- immune complexes are deposited into tissues and the resulting INFLAMMATION destroys the tissue

Type 4 hypersensitivity

Delayed hypersensitivity

key characteristics of type 4

Delayed hypersensitivity response NO antibody involvement

key immune cells in type 4

T cells (NO B cells!) Cytokines Mast cells and macrophages

etiology of type 4

Delayed cellular reaction to an antigen

possible antigens in type 4

Plant oils Cosmetics, clothing, dyes, adhesives Nickel alloys Tuberculin antigen Organ transplant or skin graft Gluten

type 4 Pathogenesis

1. Small, incomplete antigen, called a ‘hapten’, penetrates the skin 2. The hapten combines with human protein to form complete antigen 3. T cells become aware of antigen Antigen processing cell 4. T cells attack the antigen via: Direct attack of the T cells Release of cytokines (inflammation) Macrophages (cell destruction)

Type 4 clinical manifestations

Generally peak 48-72 hours Contact dermatitis Redness, edema, itching, blisters Tuberculin hypersensitivity: Redness, induration, and inflammation

4 different types of hypersensitivity

Type I Allergens IgE on Mast Cells Mediator release Type II IgG & IgM Antibodies Attach to cells Cell lysis Type III IgG or IgM – Antibody complexes Accumulate in tissues Inflammation Type IV Delayed Tcell activation Cytokines

Treatment options of hypersensitivity include

Immunosuppressants Antihistamines Epinephrine

what does ANTIHISTAMINES do

Suppress histamine mediator activity

What do Immunosuppressants (including corticosteroids) do

Suppresses cell-mediated immunity Antiinflammatory

what does epinephrine do

halts mediator activity

epinephrine class

Vasopressor, bronchodilator, antiasthmatic, vasoconstrictor

indication of epinephrine

Severe allergic reactions, cardiac arrest, severe asthmatic attack

action of epinephrine

Inhibits release of mediators from mast cells

Major Side/Adverse Effects of Epinephrine

CV: Angina, arrhythmias, hypertension, tachycardia CNS: Nervousness, restlessness, tremor

Epinephrine routes

All except PO SQ preferred

Dosage of Epinephrine

Adults: 0.2 to 1 mg Peds: 0.01/mg/kg

How is epinephrine supplied

1 mg in 1 mL vial (1:1000) concentration

What do we monitor for in Epinephrine

Vital signs closely! Status for reversal of symptoms

Nursing implications for epi dosing

Correct dose is crucial Overdose can be FATAL Have coworker recheck dose For subcu use – use TB syringe

home use of Epi

Teach: take EXACTLY as directed Contact clinician directly after taking!

Hypersensitivity Flashcards

(55 cards)