Peanut-Sensitized Infants with Eczema Already Co-Sensitized to Tree Nuts

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A very high number of infants and toddlers who have been peanut-sensitized and live with eczema are already co-sensitized to tree nuts, according to recent findings, suggesting a high likelihood for allergic reactions in a considerable number of such individuals.¹

These data suggest the potential value in determining specific IgE (sIgE) to tree nuts among children who are peanut-sensitized if tree nuts have not yet been consumed. The data result from new research led by Lara Meixner, MSc, from the department of pediatric respiratory medicine at the Universitätsmedizin Berlin in Germany.

The investigators highlighted recent increases in popularity of tree nuts such as cashews and hazelnuts among the rising number of vegan and plant-based diets.² Such dietary habit shifts may result in a wider spread of tree nut allergens and peanut allergy has been previously suggested to lead to increases in likelihood of being allergic to tree nuts versus the general population.³

“Therefore, the aim of this study was to investigate how often peanut-sensitized infants and toddlers are sensitized to cashew, hazelnut and walnut as well as their seed storage proteins, which might be associated with a high risk for clinical reactivity,” Meixner and colleagues wrote.¹

Background and Trial Design

The investigative team looked at data on both infants and toddlers who had been referred to the department of pediatric respiratory medicine, immunology, and critical care medicine at Charité—Universitätsmedizin Berlin. Among these children, some had been given oral food challenges (OFCs) due to their routine diagnostic procedures between 2007 - 2020.

The team collected clinical information as well as blood samples from all of the participants, requiring participants to be 2 years of age or younger. Additionally, they were required to have had specific IgE (sIgE) levels to peanut at or above 0.1 kU/l.

The investigators’ conducted their detection of sIgE to hazelnut, peanut, walnut, cashew, and their respective 2S albumins (Cor a 14, Ara h 2, Jug r 1, Ana o 3) in addition to the 7S vicilin-like globulin Ara h 1, through the use of the NOVEOSTM immunoanalyzer from Garden Grove, California. They defined sensitization as the presence of an sIgE level of 0.1 kU/l at least.

For the purposes of evaluating subjects’ likelihood of positive food challenges for hazelnut and cashew, probability curves were applied, correlating the resulting outcomes with Cor a 14-sIgE and Ana o 3-sIgE levels, respectively. However, given that no probability curve exists for walnut, the team concluded that it was impossible to determine one’s individual risk of one’s positive OFC for such an allergen.

The researchers assessed sera from 101 patients who had been sensitized to peanuts (defined as peanut-sIgE ≥0.1 kU/l). During the time of the investigators’ blood collection period, they noted that their subjects’ median ages was 16 months, though a range between 5 - 24 months was reported. They added that 98% also had eczema.

Notable Findings

The researchers concluded that sIgE levels of ≥0.1 kU/l were present among 96.0% of the participants for at least 1 tree nut. The team reported that 94.1% of the evaluated children were sensitized to hazelnuts, followed by walnuts at 87.1%, and cashews at 84.2%.

The investigators noted that sensitization to 1 2S albumin at least was observed among 58.4% of subjects. They added that 41.6% showed sensitization to both Cor a 14 and Jug r 1 and 39.6% showed sensitization to Ana o 3.

Among a subset of 101 peanut-sensitized children in the analysis, the research team found that 5.0% showed a 90% probability of hazelnut reaction and 13.9% to cashews. In total, 15.8% of those who were peanut-sensitized were predicted by the team to have at least a 90% probability of having allergies to cashews and/or hazelnuts.

Overall, the investigators concluded that peanut-sensitized infants and toddlers are frequently co-sensitized to tree nuts and their 2S albumins. It was also noted 98% of the analysis’s subjects suffered from eczema, a known risk factor for sensitization and the development of food allergy.

“A few limitations of our study have to be mentioned. As this was a retrospective analysis of stored serum samples, we had no data on the clinical relevance of the tree nut sensitization,” they wrote. “In particular, we lacked information on whether an oral food challenge had been conducted or what its outcome was. Moreover, the period of study inclusion was relatively long (2007–2020).”¹

References

1. ^{Meixner L, Heller S, Bluhme F, Trendelenburg V, Beyer K, Kalb B. Infants and toddlers with sensitization to peanut are often co-sensitized to tree nuts. Clin Transl Allergy. 2024;e70008. https://doi.org/10.1002/clt2.70008.}
2. ^{Reese I, Schäfer C, Ballmer-Weber B, et al. Vegan diets from an allergy point of view - position paper of the DGAKI working group on food allergy. Allergol Select. 2023; 7(1): 57-83. https://doi.org/10.5414/alx02400e.}
3. ^{McWilliam V, Peters R, Tang MLK, et al. Patterns of tree nut sensitization and allergy in the first 6 years of life in a population-based cohort. J Allergy Clin Immunol. 2019; 143(2): 644-650.e5.}