Background Due to changes in dietary habits tree nuts (TN) are consumed in many households and TN allergy appears to be increasing. One risk factor seems to be allergies to other food such as peanuts. The aim of our study was to investigate, how often peanut-sensitized infants and toddlers are co-sensitized to cashew, hazelnut and walnut and to determine the likelihood of its clinical relevance by their 2S albumin-specific (s)IgE. Methods Sera of 101 peanut-sensitized children, 5 to 24 months of age (median 16 months) were analyzed regarding sIgE to hazelnut, walnut and cashew and to their 2S-albumins Cor a 14, Jug r 1 and Ana o 3 as well as to Ara h 1 and 2, by using the NOVEOS TM immunoanalyzer system. Results 96% of the peanut-sensitized children were co-sensitized to at least one TN with 94.1% to hazelnut, 87.1% to walnut and 84.2% to cashew. More than half (58.4%) of the children were sensitized to at least one 2S albumin with similar rates for infants and toddlers, 26.7% to all three. Moreover, sensitization rates were similar in peanut allergic and tolerant children. Estimating the likelihood of clinical relevance, 15.8% of all peanut-sensitized children had an at least 90% probability to be hazelnut and/or cashew allergic. Conclusion TN sensitization seems to be common among peanut-sensitized infants and toddlers. Many had a high likelihood to be TN allergic. Therefore, it should be considered to determine TN-sIgE in peanut-sensitized children if TN are not consumed so far.

Background: In order to determine tolerance development in hen’s egg (HE) allergic children, international guidelines recommend an oral food challenge after 6-24 months. This study aimed to assess whether parents follow this advice and factors that influence their decision. Methods: A follow-up of 158 challenge-proven HE allergic children was performed. Families who did not come to a rechallenge were contacted by phone and a standardized survey relating to the current allergy status was conducted. Logistic regression models were used to assess the effect of clinical and laboratory characteristics on the reevaluation of the allergy status. Results: 35% of the HE-allergic children conducted a rechallenge in a hospital, 27% continued avoiding HE without reevaluation and 11% performed a “home-testing” with HE. The odds ratio for patients to test for HE tolerance at home instead of in a hospital increased 7.94 times (CI:2.31-27.31) for every decrease in the severity score at the initial challenge, and 3.24 times (CI:1.26-8.33) for every decrease of the baseline specific IgE CAP-class. Tolerance of heated HE prior to reevaluation was most frequent in the home-tested (100%) and was more frequent in patients, who continued avoidance (68%) compared to those, who were rechallenged (44%). Conclusions: Our data suggest an association between reaction severity as well as specific IgE levels at initial food challenge and the choice of families whether and how to evaluate natural tolerance development in their HE-allergic child. Individualized management may be needed in order to achieve safe and effective medical care for these patients.