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Allergy Immunology Board Review

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Type 1 IgE Mediated Anaphylactic Reaction. Examples: Allergic ... Examples: Serum Sickness, Immune Complex Mediated ... Examples: Poison Ivy, PPD ... – PowerPoint PPT presentation

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Title: Allergy Immunology Board Review


1
Allergy/ ImmunologyBoard Review
  • December 17, 2007

2
Overview of Topics
  • Allergic Reactions Types 1-4
  • Systemic Anaphylaxis
  • Stings
  • Allergic Reactions to Foods, Contrast and Latex
  • Serum Sickness
  • Allergy Testing
  • Therapy
  • Medications
  • Immunotherapy
  • Physical Exam Findings
  • Allergic and Vernal Conjunctivitis

3
Allergic ReactionsTypes 1-4
  • Type 1 IgE Mediated Anaphylactic Reaction
  • Examples Allergic Rhinitis, Urticaria
  • Type 2 Mediated by Antibodies
  • Examples Autoimmune Hemolytic Anemia, Rh and
    ABO Incompatibility
  • Type 3 Immune Complex
  • Examples Serum Sickness, Immune Complex
    Mediated Renal Diseases
  • Type 4 Delayed Hypersensitivity
  • Examples Poison Ivy, PPD Reactions

4
Urticaria
  • Well circumscribed, raised, palpable wheals that
    blanch with applied pressure
  • Usually erythematous but may be pale or white
    with red halos

5
Allergic Rhinitis
  • Eosinophilic Inflammation of Nasal Mucosa
  • Look for transverse nasal crease on physical exam
  • Eosinophils will be present in nasal secretions
  • Non-allergic rhinitis can be
  • Vasomotor rhinitis -presents with congestion,
    rhinnorhea and post nasal drainage unrelated to
    any trigger or infectious agent.
  • Infectious rhinosinusitis -younger children
    worse in the winter
  • Foreign body

6
Allergic Rhinitis Medications
  • Mild Antihistamine prn or routine in season
  • Moderate Routine administration or Leukotriene
    Receptor Antagonist (LTRA)
  • If poor response topical nasal steroid. If
    needed most of the year add immunotherapy.
  • Severe Topical nasal steroid, Immunotherapy,
    Antihistamine or LTRA, Rarely Brief oral
    Corticosteroid

7
Systemic Anaphylaxis
  • Due to widespread degranulation of mast cells
    after crosslinking of IgE on the mast cell
    surface.
  • Rapid. Often after bee stings, food exposure, or
    drug administration.
  • Severe Manifestations Airway obstruction and
    hypotension
  • Other signs Urticaria, Angioedema

8
Stings
  • Treatment Children younger than 16 with diffuse
    urticaria require epinephrine.
  • Children gt16 are treated as adults and require
    subcutaneous epi.
  • Any child with a systemic reaction to a bee sting
    requires referral to an allergist.
  • Any child with a life threatening reaction to a
    bee sting requires venom immunotherapy which is
    98 effective in preventing future reactions.

9
Food Allergy
  • Immune Mediated Reactions
  • IgE Mediated (Hypersensitivity)
  • Symptoms Shortly after exposure
  • Skin, Respiratory or GI manifestations
  • Symptoms gt2 hrs post exposure uncommon

10
Food Allergy Anaphylaxis
  • Severe systemic reaction not uncommon
  • Asthmatics with peanut allergy are the highest
    risk group.
  • Likeliest allergens
  • Infants and toddlers Egg, Peanut, Milk
  • Older kids Peanut, Nut, Fish, Shellfish
  • Therapy EducationAvoidance
  • Emergency Planning Epi Pen and a plan

11
Serum Sickness
  • Circulating complexes of antibody and antigen
  • Prior exposure not necessary
  • Due to fairly persistent drug or hapten
  • If severe steroids should suppress symptoms
  • Classically associated with animal sera
    (diphtheria)
  • Modern settings Anti-venom for snake bites,
    Non-humanized monoclonal antibodies

12
Anaphylaxis Therapy
  • Epinephrine is primary
  • Antihistamines are secondary
  • For severe event steroids may prevent late phase
    reaction.

13
Angioedema
  • Hereditary Angioedema Autosomal Dominant
    Disorder characterized by the absence or abnormal
    function of the C1 Esterase Inhibitor which
    results in increased vascular permeability.
  • Angioedema related to allergic reaction Self
    limiting, episodic, commonly triggered by minor
    trauma.

14
Allergic Reaction to Contrast Media
  • Contrast reactions are not IgE mediated. They are
    an osmolality hypertonicity reaction that
    triggers degranulation of mast cells and
    basophils with release of mediators that then
    cause the reactions.

15
Latex Allergy
  • Significant problem in 80s 90s due to increased
    latex exposure with universal precautions.
  • Pediatric high risk groups Spina Bifida gt40
  • Any child with repeated surgery early in life

16
Common Indoor and Outdoor Allergens
  • Indoor Cat, Dog, Dust Mites, Cockroach, Molds
  • Outdoor Pollens, Molds
  • Seasonality--
  • Spring Trees, Some Molds
  • Summer Grasses, Molds, Weeds
  • Late Summer Ragweed, Mold

17
Skin Testing
  • Useful to diagnose Type I Hypersensitivity
    Reactions
  • In vivo method to detect the presence of IgE
    antibodies to specific allergens.
  • Test interpreted by measuring the maximum
    diameter of the wheal and the flare and by
    comparison with control site.
  • Contraindications recent antihistamine use, skin
    disease in testing area, during asthma
    exacerbation or episode of anaphylaxis, if taking
    B blocker

18
RAST
  • RAST is done in vitro.
  • Is not impacted by antihistamine treatment like
    skin testing
  • No risk for anaphylactic reaction unlike skin
    testing

19
Allergy Therapy
  • Avoidance of Allergen
  • Medication
  • Allergen Immunotherapy
  • Anti-IgE
  • Prevention of Sensitization

20
Allergy Medications
  • Antihistamines
  • 1st generation sedation problems
  • 2nd generation preferred where sedation a
    problem
  • Leukotriene receptor antagonists (LTRA)
  • Similar efficacy to antihistamines
  • Mast Cell Stabilizers
  • Topical Corticosteroids
  • Most effective, block more aspects of
    allergic inflammatory response

21
Allergy Immunotherapy
  • Proven benefit for allergic rhinitis
  • Mixed studies with asthma
  • Not indicated for atopic dermatitis
  • Not indicated for food allergy

22
Allergy-Physical Exam
  • Eyes Dennie-Morgan (infra-orbital pleats),
    Infra-orbital (allergic) shiners
  • Nose Boggy mucosa and airway impairment,
    Transverse nasal crease
  • Throat/Mouth Overbite, Lymphoid Cobblestoning of
    posterior pharyngeal wall
  • Lungs Wheezing
  • Skin Eczema

23
Ocular Allergies
  • My involve eyelid or conjunctiva
  • Occur when exposed to triggering agent

24
Allergic Conjunctivitis
  • Allergic Conjunctivitis
  • Acute or Chronic, Seasonal or Perennial
  • Itching and Excessive tearing
  • Physical Finding Allergic Cobblestoning with
    fine granular appearance of the conjunctiva

25
Vernal Conjunctivitis
  • Uncommon and Chronic
  • Mostly in young atopic boys
  • Symptoms Severe itching, photophobia, blurring
    of vision, and tearing
  • Physical Exam Finding White, Ropy secretions
    that contain many eosinophils, may see
    hypertrophic nodular papillae that resembles
    cobblestones usually on the upper eyelid.
  • May be due to build up on foreign objects being
    placed in the eyes such as contacts for long
    durations with chronic exposure
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