Abstract

Background The prevalence of sesame allergy (SA) is increasing but little is known about how it changes over time. Our aims were to observe the natural history of sesame over time and the changes in biomarkers between sesame allergic and sesame sensitised but tolerant (SS) children. Methods Participants were recruited from the EAT and EAT‐On studies in the UK who were exclusively breastfed babies seen at 3‐months (m) old and followed up until 7–12 years (y) old. Clinical characteristics, skin prick test (SPT), sesame‐specific IgE (sIgE), Ses i 1‐sIgE and mast cell activation test (MAT) to sesame were assessed at 12 m, 36 m and 7–12 y. SA status was determined at 7–12 y. Results The period prevalence of SA increased from 0.5% (6/1170) between 12 and 36 m to 1.5% (14/947) between 7 and 12 y, with 71.4% of cases developing after 36 m. Longitudinal biomarker analyses were performed on SA and SS children (n = 301): 4 had persistent SA, 10 had new SA, 1 outgrew SA and 286 were SS. Children with SA at 7–12 y had larger SPT at 36 m and at 7–12 y, higher sesame‐sIgE and Ses i 1‐sIgE levels from 12 m onwards compared to SS children (p < 0.001). There were small but significant differences in MAT. A larger increase of sesame‐sIgE and Ses i 1‐sIgE from 12 to 36 m was predictive of new SA at 7–12 y. Conclusion The period prevalence of SA increased from 0.5% between 12 and 36 m to 1.5% between 7 and 12 y in a general population. Sesame‐sIgE and Ses i 1‐sIgE are informative biomarkers in terms of SA development, persistence and resolution.