Allergies Flashcards
Immune System
Network of cells, tissues, organs that work together to defend body against attacks by foreign invaders.
Key to healthy immune system
Ability to distinguish btwn own cells & foreign cell
3 Functions of Immune System
Defense Homeostasis Surveillance
Allergy
-adverse reaction to foreign subst that doesn’t normally → reaction - antigen & antibody interaction
Atopy
genetic trait predisposing for localized anaphylaxis
Antigen
Foreign body –>formation of antibodies Most composed of protein All of body’s cells have antigens that identify cell as self or non-self.
Four Methods by which Antigen Enters the Body
1) Ingestion 2) Inhalation 3) Injection 4) Absorption
Ingestion
proteins – milk, wheat, egg whites
Inhalation
pollen, dust, old spores
Injections
PCN (penicillin)
Absorption
Across skin/ mucous membrane
Antibody
- synthesized by B lymphocytes in response to antigen - proteins/ immunoglobulins
Two types of lymphocytes
o B lymphocytes o T lymphocytes (t for thymus)
B lymphocytes
in the bone marrow • Differentiate into plasma cells when activated • → antibodies
T lymphocytes (t for thymus)
cells moved from bone marrow to thymus • 70-80% of circulating lymp • immunity to viruses, tumor cells, & fungus • attack infected or cancerous cells.
Humoral Immunity
Antibody-mediated immunity Pathogen (bacteria) enters body–>encounter B lymph. specific for antigens, B cell activated –> differentiates into mature plasma cells→ secrete immunoglobulins.
Five types of immunoglobulins (antibodies):
IgG IgM IgA IgD IgE
IgG
- crosses placenta–> newborn w/ passive immunity (3+ mo.)
- -> secondary immune response
IgM
- 1st type of antibody formed
- Primary Immune Response- can kill bacteria
- Large in size-confined to intravascular space
- Blood Incompatibility Reaction
IgA
- Protects against infection in _intestines & respiratory trac_t.
- Lines mucous membranes & protects body surfaces.
IgD
o Present on lymphocyte surface. o Assists in: differeientiation of B lymph
IgE
- –>symptoms of allergic reactions.
- Hayfever, asthma, eczema.
- ** Fixes to mast cells & basophils--> releases histamines**
- defend against parasites.
Cell-Mediated Immunity
- initiated via specific antigen recognition by T cells
- –> Immunity against pathogens that live i/s cells – Virus, some bacteria, fungal infections, tumor immunity, tissue transplant, contact hypersensitivity
Sequence of Events in Immune Response
1) Antigen introduced into body. 2) Initial latent period (induction period) - no antibodies can be detected in serum. 3) Rapid rise in antibody production - peaks & then declines to maintenance level o both IgG & IgM antibodies present in primary response (IgM higher) 4) If antigen introduced again, antibody responds again much more rapidly & reaches higher titer. IgG - main antibody produced w/ repeated antigen stimulation
Hypersensitivity Reactions
- abnormal/ allergic reaction to antigen-antibody formation
- Classified by source of antigen, time sequence, mechanism (4Types)
- immune response is over reactive against antigen
- Autoimmune disease- body fails to recognize self-proteins
Five types of Hypersensitivity Reactions:
Type I: Anaphylactic Reactions (Immediate) Type II: Cytotoxic and Cytolytic Reactions Type III: Immune Complex Reactions Type IV: Delayed Hypersensitivity Reactions Type V: Stimulatory Reactions
Type I: Anaphylactic Reactions (Immediate)
Only in susceptible persons highly sensitized to specific allergens.
- IgE antibodies produced in response to antigen.
- S&S – Local/ systemic depending on mediator
Examples of Type I
allergic rhinitis (hayfever), asthma, atopic dermatitis, food/drug allergies, urticaria
Type I Hypersensitivity Reaction
Anaphylactic Reactions (Immediate)
Type II Hypersensitivity Reaction
Cytotoxic and Cytolytic Reactions
Type III
Immune Complex Reactions
Type IV
Delayed Hypersensitivity Reactions
Type V
Stimulatory Reactions
Early mediator of Hypersensitivity Reactions
Histamine→ causes: Smooth muscle contraction & Capillary dilation (increased vascular perm → increased fluid into tissue
Substances Released During Hypersensitivity
- Histamine
- Serotonin
- Prostaglandins
- Kinins
Serotonin
- increased vascular permeability
- stimulates smooth muscle contraction.
Prostaglandins
- vasodilation
- constrict smooth muscle
Kinins
stimulate nerve endings to cause throbbing & pain
“Wheal & flare”
- Type 1
- Localized - cutaneous (skin) reaction
- Pale wheal containing edematous fluid surrounded by red flare from hyperemia.
- minutes to hrs.
- Usually not dangerous
Type 1 Systemic
- _Anaphylaxis/anaphylactic shock _
- Occurs in mins-life threatening due to bronchial constriction airway obstruction & vascular collapse.
- Death can occur
Initial S/S of **Anaphylaxis/ Anaphylactic shock **
- edema
- itching at site of exposure
- Shock follows → rapid, weak pulse, low blood pressure etc.
- Death can occur
Atopic Reactions
Inherited tendency to become sensitive to environmental allergens
Angioedema
- atopic reaction (Type 1)
- Localized cutaneous (involving deeper layers)
- Begins in face –> airway (Respiratory Complications) & so on
- –> diffuse Swelling
- Common reaction to AcE inhibitors
- Interventions must be quick b/c –> too swollen to incubate
Type II: Cytotoxic and Cytolytic Reactions
- Body makes auto-antibodies directed against self cells
- Self cells are destroyed (phagocytosis or lysis)
- Cellular tissue destroyed.
Target cells frequently destroyed in Type II reactions:
- erythrocytes
- platelets
- leukocytes.
Examples of Type II: Cytotoxic and Cytolytic Reactions
- ABO incompatibility transfusion reaction
- Rh incompatibility transfusion rx,
- Leukopenia’s
- Thrombocytopenias,
- Hemolytic anemia
Type III: Immune Complex Reactions
- Antigens + antibodies –> complexes that deposit in tissue-
- –>acute inflammation, damage to tissue, &/ or blood vessels
Common Deposit Sites for Antigen/ Antibody Complexes
(Type 3)
- kidneys
- skin
- joints
- BV
- lungs
Severe type III reactions include:
autoimmune disorders
- lupus
- rheumatoid arthritis
- acute glomerulonephritis
Type IV: Delayed Hypersensitivity Reactions
Cell Mediated Immune Response
- Tissue damage w/o presence of antibody
- T lymphocytes & macrophages destroy the antigen.
- 24-48 hrs before reaction occurs
- _Contact dermatitis, transplant rejection_s, reactions to some bacterial,
fungal, viral infections, or some drug reactions.
Type V: Stimulatory Reactions
Excessive stimulation of a normal receptor by an autoantibody = continuous “on” state.
- Ex: Graves Disease – continuously stimulated thyroid cells→ thyroid hormone → sever hyperthyroidism
- Tx = remove the tissue.
EENT
(Eyes, ears, nose, throat)
- red eyes
- itchy eyes/nose
- sniffling
- dcreased hearing
RAST
radioallergosorbent test
- Specific test for IgE antibodies to specific allergens (in vitro test).
- Expensive, Less sensitive & longer than skin tests.
- Effective for individuals with severe anaphylactic reactions
- Detect food & drug allergies.
CBC+WBC differential
lymphocyte and eosinophil counts
Sputum, nasal, bronchial secretions
can be tested for eosinophils.
Purpose of Skin Testing
- detect presence of atopic reactions to IgE in skin
- isolate antigen (allergen) to which person sensitive.
2 types of skin tests
- Scratch or prick.
- Intracutaneous
Scratch or prick
(Skin Test)
- Area washed w/ alcohol
- Drop of allergen applied to skin
- area scratched (lancet)/pricked (needle)-sterile.
- Applied in rows w/ corresponding control sites op. test rows.
Intracutaneous
- Inject sm amt of sol. of allergen below epidermis-in row (Forearm)
- Allergic reaction more severe with this method
- Only used for persons who did not react to cutaneous methods.
Precautions for Skin Testing
- Highly sensitive>at risk for anaphylactic reaction to skin tests.
- Never leave alone during skin testing
severe reaction to skin/scratch test –>
extract/ remove & anti-inflam. topical cream applied.
severe reaction to intracutaneous test –>
- tourniquet applied to arm
- subcutaneous injection of epinephrine may be needed.
_**Epinepherine = # 1 drug_
Best meds for tx of allergic rhinitis & urticarial (hives).
Antihistamines
Antihistamines
- Less effective for severe allergic reactions.
- Given orally, IV, topical, inhaled or nasal spray.
- Action = competes w/ histamines for H receptor site & blocking effect of histamines
- Best if taken when symptoms appear.
Antihistamines
(Side Effects)
- *- Side effects:** drowsiness, sedation, disturbed coordination (use caution when driving/ operating heavy machinery)
- Benadryl, Zyrtec, Chlor-trimeton.
- New generation of meds - Claritin, Zyrtec, Allegra, Clarinex = decrease side effects.
Major sympathomimetic med
epi (adrenalin)
Sympathomimetic/Decongestant Meds
Epi
- Drug of choice for anaphylactic reaction.
- Hormone produced by adrenal medulla–> A & B-adrenergic receptors
- →Vasoconstriction of peripheral blood vessels = decreases edema
- Stimulation of B Receptors relaxes bronchial smooth muscle spasms
- Last only a few minutes
Corticosteroids
- Nasal corticosteroids (vancenase, rhinocort, flonase)
- *- Relieve symptoms of allergic rhinitis**
- Oral corticosteroids: brief course for severe reactions – bad side effects
Antipruritics
- Topically applied.
- Most effective when skin intact
- Provide relief from itching.
- OTC- calamine or Benadryl liquidyne
Mast-Cell Stabilizing Drugs
- Inhibit release of histamines, leukotrienes (chemical mediators of inflam) & other agents from mast cells
- Inhalant nebulizer, nasal spray, po
- Examples: Cromolyn spray (intal, nasalcrom) – decrease side effects.
- Use before exposure to allergen-(cats, pollen season)
Immunotherapy
- For anaphylactic reactions → desensitization
- Given injections weekly for up to 5 years – Allergy shots
- injections may –> reaction. Use arm - monitor 20 mins.
- May need maintenance for severe reactions to insects
- Attempt to _stimulate IgG levels to mediate IgE to mast cells–>_reduces reactions & tissue damage.
Anaphylaxis (type 1 systemic)
- sudden hypersensitive rx w/ exposure to allergen
- Can occur after injection of drugs (abx), blood products, insect stings.
- Mild symptoms: puritus & urticaria
- Severe symptoms: bronchial constriction, airway obstruction, vascular collapse, (shock)
5 principles in therapeutic management of anaphylaxis:
(speed in)
- recognition of anaphylactic reaction
- maintenance of patent airway
- prevention of spread of allergen by using tourniquet (i.e.snake bites).
- med administration.
- treatment for shock.
Serum Sickness
- Type III reaction (systemic)
- deposits of antigen-antibody complexes in blood vessel walls of skin, joints, in renal glomeruli
- Develops slowly (10 -14 days)
- Self limiting – will resolve on own
- **don’t need to be previously sensitized to react **
Triggers for serum sickness
- PCN, other abx
- Animal serum based drugs
Serum Sickness
Signs and Symptoms:
- urticaris
- angioedema,
- fever
- muscle soreness
- malaise
- lymphadenopathy
- joint pain
- polyarthritis
- nephritis
Latex Containing Products
Items Containig Latex
- Torniquets
- BP cuffs
- IV tubing
- Syringes
- Electode pads
- O2 masks/tubing
- Colostomy pouches
Two types of latex allergies:
- Type IV allergic contact dermatitis
- Type I allergic reaction
latex allergies: Type IV allergic contact dermatitis
- Caused by chemicals used in manufacturing process of latex gloves.
- Delayed reaction – 6-48 hrs
- Symptoms = dryness, prutitus, fissuring, cracking of skin, followed by rednesss, swelling, crusting at 24-48 hours
latex allergies: Type I allergic reaction
- Response to natural rubber latex proteins & occurs w/in mins of contact with proteins.
- Symptoms: Skin rednesss, Urticarial, Rhinitis, Conjunctivitis, Asthma, Full blown anaphylactic shock
Risk factors for latex sensitivity:
- Long term multiple exposures to latex products (health care staff, pts with many OR visits)
- Hx Hayfever or Asthmas
Food Allergies For Latex
- Avocados
- Guava
- Kiwi
- Bananas
- Water chestneuts
- Hazelnuts
