Allergy/ Immunology Board Review December 17, 2007

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

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

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

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

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

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

Stings Treatment: Children younger than 16 with diffuse urticaria require epinephrine. Treatment: Children younger than 16 with diffuse urticaria require epinephrine. Children >16 are treated as adults and require subcutaneous epi. Children >16 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 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. Any child with a life threatening reaction to a bee sting requires venom immunotherapy which is 98% effective in preventing future reactions.

Food Allergy Immune Mediated Reactions Immune Mediated Reactions IgE Mediated (Hypersensitivity)— IgE Mediated (Hypersensitivity)— Symptoms: Shortly after exposure Symptoms: Shortly after exposure Skin, Respiratory or GI manifestations Skin, Respiratory or GI manifestations Symptoms >2 hrs post exposure uncommon Symptoms >2 hrs post exposure uncommon

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

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

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

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

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. 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.

Latex Allergy Significant problem in 80s 90s due to increased latex exposure with universal precautions. Significant problem in 80s 90s due to increased latex exposure with universal precautions. Pediatric high risk groups: Spina Bifida >40% Pediatric high risk groups: Spina Bifida >40% Any child with repeated surgery early in life Any child with repeated surgery early in life

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

Skin Testing Useful to diagnose Type I Hypersensitivity Reactions Useful to diagnose Type I Hypersensitivity Reactions In vivo method to detect the presence of IgE antibodies to specific allergens. 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. 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 Contraindications: recent antihistamine use, skin disease in testing area, during asthma exacerbation or episode of anaphylaxis, if taking B blocker

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

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

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

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

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

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

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

Vernal Conjunctivitis Uncommon and Chronic Uncommon and Chronic Mostly in young atopic boys Mostly in young atopic boys Symptoms: Severe itching, photophobia, blurring of vision, and tearing 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. 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 May be due to build up on foreign objects being placed in the eyes such as contacts for long durations with chronic exposure