Peanut allergy and cross-reactivity: Differentiating between symptoms caused by clinical peanut allergy and symptoms caused by cross-reactivity
Caroline and Emma, both 16 years old, both of whom possess known peanut allergies, visit their healthcare provider after experiencing nasal obstruction in combination with irritated, itchy eyes and sometimes local reaction in the mouth.
Caroline and Emma's healthcare provider conducts a full clinical history and physical examination and decides to test using peanut components.
Find out how allergen sensitization testing can show if two girls are at risk for severe reactions to peanuts.
Patient History
Family History
- None
Caroline and Emma's Personal History
- Eczema during infancy; outgrown at school age.
- Rhinitis and conjunctivitis during pollen season, since school age.
Test |
Type |
Caroline’s Results |
Emma’s Results |
Peanut |
Whole Allergen |
+4 |
+4 |
Based on history, evaluation, and testing their previous healthcare provider recommended that Caroline and Emma remove peanut entirely from thier diet.
Caroline and Emma’s ImmunoCAP™ Test Results
These results together with these patients’ case history and symptoms, help confirm the diagnosis.
Test |
Type |
Caroline’s Results |
Emma’s Results |
Peanut |
Whole Allergen |
26 |
28 |
Ara h 1 |
Allergen Component |
<0.1 |
2.1 |
Ara h 2 |
Allergen Component |
<0.1 |
12.3 |
Ara h 3 |
Allergen Component |
<0.1 |
3.3 |
Ara h 8 |
Allergen Component |
33 |
10.3 |
Ara h 9 |
Allergen Component |
<0.1 |
<0.1 |
Differential Diagnosis
Caroline
Caroline has no detectable IgE levels to any of the species-specific markers in peanut allergy; Ara h 1, Ara h 2, and Ara h 3. Also, Ara h 9 is negative. She does however, have high levels of antibodies recognizing Ara h 8 indicating a pollen-related food allergy, which is in line with her symptoms during spring season.1-3
REFINED DIAGNOSIS
- Birch allergy and a pollen-related food allergy.
HEALTHCARE PROVIDER MANAGEMENT PLAN
- Her healthcare provider advises Caroline that she may be an ideal candidate for a supervised oral food challenge.
- Her healthcare provider refers Caroline to an allergy specialist for a supervised oral food challenge with peanut.
- The allergy specialist performs a supervised oral food challenge with peanut, which Caroline passes without any symptoms.
FOLLOW UP
- Caroline is seen by her healthcare provider one year later. Peanut is now part of Caroline’s diet and she is doing well.
Emma
Emma has significant/high IgE to species specific markers for peanut allergy often associated with systemic reactions.1-3
REFINED DIAGNOSIS
- Emma’s component sensitization profile confirms a clinical peanut allergy.
HEALTHCARE PROVIDER MANAGEMENT PLAN
- Her healthcare provider advises Emma to continue to strictly avoid peanuts.
- Her healthcare provider also advises Emma to always carry her emergency adrenaline autoinjector.
FOLLOW UP
- Emma is seen by her healthcare provider one year later. She has continued to avoid peanut in all forms and is fit and well. Emma's healthcare provider checks her autoinjector technique and is satisfied.
The people, places, and events depicted in these case studies and photographs do not represent actual patients, nor are they affiliated in any way with Thermo Fisher Scientific.
- Asarnoj A, Nilsson C, Lidholm J, et al. Peanut component Ara h 8 sensitization and tolerance to peanut. J Allergy Clin Immunol. 2012;130(2):468-472
- Peeters KA, Koppelman SJ, van Hoffen E, et al. Does skin prick test reactivity to purifed allergens correlate with clinical severity of peanut allergy? Clin Exp Allergy. 2007;37(1):108-115.
- Asarnoj A, Movérare R, Östblom E, et al. IgE to peanut allergen components: relation to peanut symptoms and pollen sensitization in 8-year-olds. Allergy. 2010;65(9):1189-1195.
