Allergies Flashcards
(83 cards)
1
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Immune System
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Network of cells, tissues, organs that work together to defend body against attacks by foreign invaders.
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Key to healthy immune system
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Ability to distinguish btwn own cells & foreign cell
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3 Functions of Immune System
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Defense Homeostasis Surveillance
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Allergy
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-adverse reaction to foreign subst that doesn’t normally → reaction - antigen & antibody interaction
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Atopy
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genetic trait predisposing for localized anaphylaxis
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Antigen
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Foreign body –>formation of antibodies Most composed of protein All of body’s cells have antigens that identify cell as self or non-self.
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Four Methods by which Antigen Enters the Body
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1) Ingestion 2) Inhalation 3) Injection 4) Absorption
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Ingestion
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proteins – milk, wheat, egg whites
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Inhalation
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pollen, dust, old spores
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Injections
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PCN (penicillin)
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Absorption
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Across skin/ mucous membrane
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Antibody
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- synthesized by B lymphocytes in response to antigen - proteins/ immunoglobulins
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Two types of lymphocytes
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o B lymphocytes o T lymphocytes (t for thymus)
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B lymphocytes
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in the bone marrow • Differentiate into plasma cells when activated • → antibodies
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T lymphocytes (t for thymus)
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cells moved from bone marrow to thymus • 70-80% of circulating lymp • immunity to viruses, tumor cells, & fungus • attack infected or cancerous cells.
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Humoral Immunity
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Antibody-mediated immunity Pathogen (bacteria) enters body–>encounter B lymph. specific for antigens, B cell activated –> differentiates into mature plasma cells→ secrete immunoglobulins.
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Five types of immunoglobulins (antibodies):
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IgG IgM IgA IgD IgE
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IgG
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- crosses placenta–> newborn w/ passive immunity (3+ mo.)
- -> secondary immune response
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IgM
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- 1st type of antibody formed
- Primary Immune Response- can kill bacteria
- Large in size-confined to intravascular space
- Blood Incompatibility Reaction
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IgA
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- Protects against infection in _intestines & respiratory trac_t.
- Lines mucous membranes & protects body surfaces.
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IgD
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o Present on lymphocyte surface. o Assists in: differeientiation of B lymph
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IgE
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- –>symptoms of allergic reactions.
- Hayfever, asthma, eczema.
- ** Fixes to mast cells & basophils--> releases histamines**
- defend against parasites.
23
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Cell-Mediated Immunity
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- 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
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Sequence of Events in Immune Response
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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
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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
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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
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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
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Examples of Type I
allergic rhinitis (hayfever), asthma, atopic dermatitis, food/drug allergies, urticaria
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Type I Hypersensitivity Reaction
Anaphylactic Reactions (Immediate)
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Type II Hypersensitivity Reaction
Cytotoxic and Cytolytic Reactions
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Type III
Immune Complex Reactions
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Type IV
Delayed Hypersensitivity Reactions
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Type V
Stimulatory Reactions
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Early mediator of Hypersensitivity Reactions
Histamine→ causes: Smooth muscle contraction & Capillary dilation (increased vascular perm → increased fluid into tissue
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Substances Released During Hypersensitivity
* Histamine
* Serotonin
* Prostaglandins
* Kinins
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Serotonin
* increased **vascular permeability**
* **stimulates smooth muscle contraction.**
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Prostaglandins
* vasodilation
* constrict smooth muscle
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Kinins
stimulate _nerve endings_ to cause throbbing & _pain_
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“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
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Type 1 Systemic
* **_Anaphylaxis/anaphylactic shock _**
* **_Occurs in mins-life threatening_** due to bronchial constriction airway obstruction & vascular collapse.
* Death can occur
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**_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
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Atopic Reactions
**Inherited** tendency to become **sensitive to environmental allergens**
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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
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Type II: Cytotoxic and Cytolytic Reactions
1. Body makes **auto-antibodies directed against self cells**
2. **Self cells are destroyed (**phagocytosis or lysis)
3. Cellular tissue destroyed.
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Target cells frequently destroyed in Type II reactions:
* erythrocytes
* platelets
* leukocytes.
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Examples of Type II: Cytotoxic and Cytolytic Reactions
* ABO incompatibility transfusion reaction
* Rh incompatibility transfusion rx,
* Leukopenia’s
* Thrombocytopenias,
* Hemolytic anemia
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Type III: Immune Complex Reactions
* Antigens + antibodies --\> complexes that deposit in tissue-
* --\>acute inflammation, damage to tissue, &/ or blood vessels
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Common Deposit Sites for Antigen/ Antibody Complexes
(Type 3)
* kidneys
* skin
* joints
* BV
* lungs
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Severe type III reactions include:
**autoimmune disorders**
* lupus
* rheumatoid arthritis
* acute glomerulonephritis
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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.
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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.
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EENT
**(Eyes, ears, nose, throat)**
* red eyes
* itchy eyes/nose
* sniffling
* dcreased hearing
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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_.
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CBC+WBC differential
lymphocyte and eosinophil counts
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Sputum, nasal, bronchial secretions
can be tested for **eosinophils.**
## Footnote
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Purpose of Skin Testing
* detect presence of **_atopic reactions to IgE in skin_**
* **_isolate antigen (allergen)_** to which person sensitive.
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2 types of skin tests
1. Scratch or prick.
2. Intracutaneous
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Scratch or prick
| (Skin Test)
1. Area _washed_ w/ alcohol
2. Drop of _allergen applied to skin_
3. _area scratched_ (lancet)/pricked (needle)-sterile.
4. Applied in rows w/ corresponding control sites op. test rows.
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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_**.
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Precautions for Skin Testing
* Highly sensitive\>**at risk for anaphylactic reaction** to skin tests.
* **_Never_** leave alone during skin testing
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severe reaction to **skin/scratch tes**t --\>
extract/ remove & anti-inflam. topical cream applied.
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severe reaction to intracutaneous test --\>
* **_tourniquet_** applied to arm
* _subcutaneous_ injection of **_epinephrine_** may be needed.
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_**\*\*Epinepherine = # 1 drug**_
Best meds for tx of allergic rhinitis & urticarial (hives).
Antihistamines
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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.
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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.
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Major sympathomimetic med
epi (adrenalin)
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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
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Corticosteroids
- Nasal corticosteroids (vancenase, rhinocort, flonase)
* *_- Relieve symptoms of allergic rhinitis_**
- Oral corticosteroids: brief course for severe reactions – bad side effects
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Antipruritics
- Topically applied.
- Most effective when skin intact
- Provide relief from itching.
- OTC- calamine or Benadryl liquidyne
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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)
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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.**
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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)
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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.
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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 **
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Triggers for serum sickness
* **PCN, other abx**
* Animal serum based drugs
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Serum Sickness
Signs and Symptoms:
* urticaris
* angioedema,
* fever
* muscle soreness
* malaise
* lymphadenopathy
* joint pain
* polyarthritis
* nephritis
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Latex Containing Products
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Items Containig Latex
* Torniquets
* BP cuffs
* IV tubing
* Syringes
* Electode pads
* O2 masks/tubing
* Colostomy pouches
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Two types of latex allergies:
1. Type IV allergic contact dermatitis
2. Type I allergic reaction
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**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
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**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
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Risk factors for latex sensitivity:
* **_Long term multiple exposures_** to latex products (health care staff, pts with many OR visits)
* Hx Hayfever or Asthmas
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Food Allergies For Latex
* Avocados
* Guava
* Kiwi
* Bananas
* Water chestneuts
* Hazelnuts
