Acquisition of tolerance to egg and peanut in African food-allergic children with atopic dermatitis

• Published in: South African medical journal 2019-05, Vol.109 (5), p.323-327
• Main Authors: Du Toit, G, Levin, M.E, Gray, C.L
• Format: Article
• Language: English
• Subjects: Analysis; Atopic dermatitis; Child health; Children; Comorbidity; Dermatitis; Eggs (Food); Food hypersensitivity; Health aspects; Patient outcomes; Peanuts; Reorganization and restructuring; Silicon compounds; Skin
• ISSN: 0256-9574; 2078-5135
• DOI: 10.7196/SAMJ.2019.v109i5.13339

Background. There are no previous data on tolerance development in children with atopic dermatitis (AD) and concomitant food allergy in low- and middle-income settings.Objectives. To determine the rate of tolerance acquisition to egg and peanut 5 years after diagnosing food allergies in South African (SA) children with AD, and to explore factors influencing tolerance acquisition.Methods. Five years after first diagnosing food allergy in 37 SA children with egg and/or peanut allergy, they were reassessed for their allergies by questionnaire, skin-prick tests (SPTs) and ImmunoCAP-specific IgE (sIgE) tests (Thermo Fisher Scientific/Phadia, Sweden) to egg white, ovomucoid, peanut and Arachis hypogaea allergen 2 (Ara h 2), and incremental food challenges.Results. Eighteen of 25 originally egg-allergic patients and 19 of 24 originally peanut-allergic children were followed up at a median age of 8 years and 3 months and 9 years and 6 months, respectively. A high percentage of children (72.2%) outgrew their egg allergy, and 15.8% outgrew their peanut allergy. Allergic comorbidity remained high, with asthma increasing over time, and AD remaining moderate in severity in the cohort overall. At diagnosis, sIgE egg white ≤9.0 kU/L and sIgE ovomucoid ≤2.0 kU/L were associated with tolerance development to egg 5 years later. At follow-up, sIgE egg white ≤0.70 kU/L, sIgE ovomucoid ≤0.16 kU/L, SPT egg-white extract ≤1 mm and SPT fresh egg ≤5 mm were associated with tolerance. At diagnosis, sIgE Ara h 2 ≤1.7 kU/L and SPT peanut ≤10 mm were associated with tolerance development to peanut 5 years later. At follow-up, sIgE peanut ≤0.22 kU/L, sIgE Ara h 2 ≤0.18 kU/L and SPT peanut ≤5.5 mm were associated with tolerance.Conclusions. Egg allergy was outgrown in 72.2% and peanut allergy in 15.8% of SA children 5 years after diagnosis of AD. This is in keeping with findings derived from studies in higher socioeconomic settings, and can help to guide the counselling of patients with allergies to these foods of high nutritional value.