Allergy Immunology Board Review

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Allergy/ ImmunologyBoard Review

• December 17, 2007

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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

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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

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Urticaria

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

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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

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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

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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

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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.

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Food Allergy

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

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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

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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

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Anaphylaxis Therapy

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

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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.

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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.

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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

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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

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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

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RAST

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

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Allergy Therapy

• Avoidance of Allergen
• Medication
• Allergen Immunotherapy
• Anti-IgE
• Prevention of Sensitization

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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

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Allergy Immunotherapy

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

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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

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Ocular Allergies

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

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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

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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