Hypersensitivity Flashcards
what is hypersensitivity
NORMAL immune response that is:
Inappropriately triggered
OR
Excessive
OR
Produces undesirable effects on the body
what are the basic triggers for hypersensitivity
A specific antigen-antibody reaction
OR
A specific antigen-lymphocyte interaction
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)
What is Type 1 hypersensitivity
IgE mediated reaction
Type 1 key charactersitics
Immediate reaction! (15-20 minutes)
This reaction occurs after being sensitized to an antigen
Antigens for Type 1 hypersensitivity
Environmental (pet dander, bee stings)
Foods (nuts, seafood, eggs)
Medications (penicillin, contrast dye)
Etiology of type 1
1 parent allergic = 30% chance
2 parents allergic = 50% chance
key cells involved in type 1
B lymphocytes
IgE (antibody)
Mast cells (granulocyte)
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
Potent vasodilation
causes
Stuffy nose
Lower blood pressure
Wheals on skin
increased vascular permeability causes
edema
runny nose
Bronchial smooth muscle constriction causes
breathing difficulties
wheezing
Stimulates irritant receptors
causes
Itching (pruritis)
Atopic reactions =
inherited tendency to become sensitive to allergens
Examples of atopic reactions
Allergic rhinitis
Asthma
Urticaria (hives)
What are the most common triggers of atopic reactions? (4)
Pollen,
dusts,
molds,
animal dander
What is Type I: Anaphylaxis (Systemic)
systemic release of CHEMICAL MEDIATORS
Warnings about Anaphylaxis
Life-threatening– Bronchial constriction Airway obstruction Vascular collapse (shock)
Common triggers of anaphylaxis
medications
bee stings
foods
What is Type 2 hypersensitivity
Cytotoxic reaction
“WRONG BLOOD”
Etiology of Type 2
Exposure to antigen or foreign tissue/cells
Antigens are located on cell surface
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
Immune cells involved in type 2
Antibodies (IgG & IgM)
Complement
WBC’s (phagocytes)
Examples of antigens in type 2
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
- Small, incomplete antigen, called a ‘hapten’, penetrates the skin
- The hapten combines with human protein to form complete antigen
- T cells become aware of antigen
Antigen processing cell - 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!
