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Background: Tree nut (TN) allergies are the most common cause of fatal anaphylaxis and generally are ongoing food allergies throughout life. Objective: To investigate the predicting factors for TN anaphylaxis in children. Methods: Children with TN allergy were divided into anaphylactic and nonanaphylactic groups, those who had an anaphylactic reaction with at least one type of TN and those with any type of reaction other than anaphylaxis with TNs, respectively. Children with TN allergies were evaluated for the predictors of anaphylaxis by using multivariate logistic regression analysis. Results: A total of 184 children (ages 4.9 years; 3.2‐6.9 years) with TN allergy were included in the study. Of these, 90 experienced an anaphylactic type of reaction on exposure to at least one type of TNs. Comparisons of the two groups showed that concomitant asthma, skin-prick test, specific immunoglobulin E, total immunoglobulin E, and serum basal tryptase (sBT) levels were significantly higher in the anaphylactic group compared with the nonanaphylactic group. In multivariate analysis, female gender (odds ratio [OR] 4.905 [95% confidence interval {CI}, 1.266‐19.001], p = 0.021), sBT levels (OR 2.287 [95% CI, 1.431‐3.654], p < 0.001), concomitant egg white allergy (OR 4.135 [95% CI, 1.016‐16.481], p = 0.048), and concomitant asthma (OR 3.874 [95% CI, 1.109‐13.526], p = 0.034) were risk factors for anaphylaxis. The optimal cutoff value for sBT was 2.06 ng/mL, with a sensitivity of 85.9% and a specificity of 69%, as well as an area under the curve 0.810 (95% CI, 0.717‐0.903, p < 0.001). The sBT levels of 1.94 ng/mL and 5.30 ng/mL predicted clinical reactivity at 50% and 95% probabilities. Conclusion: Different aspects, including gender, higher mast cell load and/or activation, and a stronger atopic background (e.g., coexisting egg allergy, asthma), contributed to the development of anaphylactic reactions to TNs in children.

Background Beta-lactam antibiotics (BLA) are the most commonly prescribed antibiotics and are responsible for the majority of immediate hypersensitivity reactions to drugs in children. Cross-reactivity is important in hypersensitivity to BLAs because these drugs all share a common beta-lactam structure and some share similar side chains. Objective The aim of this study was to evaluate the clinical characteristics of patients who are diagnosed with immediate-type BLA hypersensitivity and frequency of patients with side chain hypersensitivity, "selective responders." Methods The study included patients who were diagnosed with immediate-type BLA hypersensitivity between January 2011 and May 2016 in a pediatric allergy outpatient clinic. The patients who had negative penicillin test (minor determinant mixture, benzylpenicilloylpoly-L-lysine, penicillin G) results and could tolerate penicillin V and/or BLAs with dissimilar side chains but had positive skin and/or provocation test results with the suspected drug were diagnosed as selective responders. Results During the study period, 357 patients (55.2% girls) were admitted to our clinic with suspected immediate-type BLA hypersensitivity. Parents of 11 patients did not give consent for an allergy workup with the suspected drug. Forty-five of the patients were diagnosed (45/346 [13%]) based on skin test or drug provocation test results. The most common susceptible agent was amoxicillin-clavulanate. Of the patients, 71.4% with a reaction to sulbactam-ampicillin /or amoxicillin-clavulanate and 93.7% with a reaction to cephalosporin were classified as selective responders. Conclusion Among children with immediate BLA hypersensitivity, selective responders constituted an important group. Most of the patients with reactions to aminopenicillin and cephalosporins safely tolerated penicillin V and BLAs with dissimilar side chains after negative allergy workup results.

BACKGROUND Increased numbers of mast cells that contain tryptase are found in lesional atopic dermatitis (AD) skin. The association of serum basal tryptase (sBT) with anaphylactic reactions and mast cell diseases has recently been shown in children with venom and food allergy. OBJECTIVE We aimed to identify the risk factors that predict the severity of AD and the association of sBT levels with AD and disease severity. METHOD AD diagnosis was made according to Hanifin and Rajka criteria. Disease severity was scored by the objective scoring atopic dermatitis (SCORAD) index. The sBT levels were measured. Skin-prick testing, total immunoglobulin E, eosinophil percentages and counts, and a questionnaire concerning the history of atopic diseases and the risk factors of AD were applied. RESULTS The children, ages 0.5 to 3.0 years, with AD (n = 85) were analyzed in two groups according to the presence (AD+/atopy+ [n = 55]) or absence (AD+/atopy- [n = 30]) of skin-prick test positivity. The comparisons were made with an age- and sex-matched control group (n = 82). The median (interquartile range) sBT in the AD+/atopy+, AD+/atopy-, and control groups were 5.01 ng/mL (2.75-6.79 ng/mL), 3.02 ng/mL (1.67-4.44 ng/mL), and 2.63 ng/mL (1.31-4.49 ng/mL), respectively (p = 0.003). The median (interquartile range) sBT levels were higher in patients with moderate-severe objective SCORAD index scores compared with the those with mild disease (3.85 ng/mL [2.04-5.91 ng/mL] versus 2.80 ng/mL [1.83-3.48 ng/mL]; p = 0.038). Multivariate logistic regression analysis showed that an sBT level of ≥3.9 ng/mL (odds ratio 8.77 [95% confidence interval, 1.87-41.18]; p = 0.006) was independently associated with an increased risk of moderate-severe AD (objective SCORAD index). CONCLUSION To our knowledge, this was the first study that indicated that sBT levels may be important in the AD disease process and associated with the disease severity and atopy.

Background The aim of this study was to determine and compare the clinical and laboratory features of food protein-induced enterocolitis syndrome (FPIES) and food protein-induced allergic proctocolitis (FPIAP), and to provide information about the short-term prognoses. Method Children diagnosed with FPIES or FPIAP between 2010 and 2015 were enrolled in this study. Results Overall, 64 infants (37 FPIAP, 27 FPIES) were evaluated, with the average age at the onset of symptoms being significantly lower in the patients with FPIAP than in the patients with FPIES (2 months [1-3 months] versus 4 months [1.5-6 months]; p = 0.043). Fifteen of the patients with FPIAP (40.5%) and six of the patients with FPIES (22.2%) were exclusively breast-fed at the time of the onset of symptoms. Cow's milk was the most frequent trigger (100% FPIAP, 74% FPIES); solid foods caused FPIES more frequently. Forty-eight of the 64 patients were followed up until at least 2 years of age, with the resolution rates being 91.3% for FPIAP and 60% for FPIES. The solid food-induced cases of FPIES (27.3%) had a significantly lower rate of resolution than the liquid food-induced FPIES (83.3%) (p = 0.003). Conclusion Cow's milk is the most common trigger of both FPIAP and FPIES. The symptom onset age seemed to be earlier in FPIAP. The resolution age was similar, however, the recovery in FPIES may be later if the trigger food is solid. To our knowledge, this was the first clinical study to compare the clinical and laboratory characteristics of patients with FPIAP and FPIES.

Tryptase is used as a marker in many clinical conditions such as mast cell activation and systemic anaphylaxis. Normal levels of the serum basal tryptase (sBT) are determined in adulthood; however, data about nonallergic healthy children is limited. This study was designed to determine the normal sBT levels in healthy children. Total sBT levels were measured in 113 sera from healthy nonallergic children, for routine follow-up or diagnosis of illnesses that are not known to induce changes in serum tryptase levels. One hundred thirteen children aged 0.16-9.91 years (male/female subjects, 68/45 [60%/40%]) with a median (interquartile) age of 3.36 years (1.94-5.68 years) were evaluated. The sBT level was determined to be 3.30 ng/mL (2.38-4.36) median (interquartile) for the whole group. There was a tendency of higher sBT levels for boys than girls (3.49 [2.56-4.64 ng/mL] and 2.91 ng/mL [2.16-4.16 ng/mL], respectively); however, these findings were not significant (p = 0.12). The analysis of the whole group revealed that sBT levels were inversely related with age (r = -0.259; p = 0.006); and the decrease of sBT with age was more prominent in girls (r = -0.282; p = 0.02) than in boys. The highest sBT levels were found in the 0- to 1-year age group (all, 4.67 ng/mL [4.04-6.39 ng/mL]; boys, 5.34 ng/mL [4.04-6.39 ng/mL]; girls, 4.48 ng/mL [3.23-16.26 ng/mL]). The sBT levels in healthy children are similar to those in adults except in infancy. Interestingly, sBT levels tend to decrease slightly with age. Although they did not reach significance, sBT levels were found to be higher in boys compared with the girls.

Data on food allergy-related comorbid diseases and the knowledge on factors associating specific food types with specific allergic outcomes are limited. The aim of this study was to determine the clinical spectrum of IgE-dependent food allergy and the specific food-related phenotypes in a group of children with IgE-mediated food allergy. Children diagnosed with IgE-mediated food allergy were included in a cross-sectional study. IgE-mediated food allergy was diagnosed in the presence of specific IgE or skin-prick test and a consistent and clear-cut history of food-related symptoms or positive open provocation test. Egg (57.8%), cow's milk (55.9%), hazelnut (21.9%), peanut (11.7%), walnut (7.6%), lentil (7.0%), wheat (5.7%), and beef (5.7%) were the most common food allergies in children with food allergy. The respiratory symptoms and pollen sensitization were more frequent in children with isolated tree nuts-peanut allergy compared with those with egg or milk allergy (p < 0.001); whereas atopic dermatitis was more frequent in children with isolated egg allergy compared with those with isolated cow's milk and tree nuts-peanut allergy (p < 0.001). Children with food allergy were 3.1 (p = 0.003) and 2.3 (p = 0.003) times more likely to have asthma in the presence of allergic rhinitis and tree nuts-peanut allergy, respectively. Interestingly, children with atopic dermatitis were 0.5 (p = 0.005) times less likely to have asthma. Asthma (odds ratio [OR], 2.3; p = 0.002) and having multiple food allergies (OR, 5.4; p < 0.001) were significant risk factors for anaphylaxis. The phenotypes of IgE-mediated food allergy are highly heterogeneous and some clinical phenotypes may be associated with the specific type of food and the number of food allergies.