Detection of Salivary Tryptase Levels in Children following Oral Food Challenges

Abstract

<b><i>Background:</i></b> Oral food challenge (OFC) is commonly used to diagnose food allergy. This test is time and resource intensive, and conclusions are not always unequivocal as this relies on the interpretation of symptoms. Therefore, an objective marker would improve the accuracy of the diagnostic workup of food allergy. <b><i>Objectives:</i></b> The aim of this study was to investigate whether tryptase can be detected in saliva of children following OFC. <b><i>Method:</i></b> Children from 3 to 18 years of age were eligible for inclusion if an OFC for peanut or tree nut had been recommended. Saliva samples were collected prior to the first dose and 5, 10, and 15 min following the last administered dose during OFC. Assay precision, spike-and-recovery, and assessment of lower limit of detection of the tryptase immunoassay were examined before analysis of tryptase in saliva was performed. <b><i>Results:</i></b> A total of 30 children were included (median age 8 years, 63.3% male, 53.3% positive OFC outcome). Tryptase was detected in saliva samples. The mean of the change in baseline tryptase value to each saliva collecting time point was significantly different in patients with a positive OFC outcome compared to a negative outcome (<i>p</i> < 0.01). <b><i>Conclusions:</i></b> This study showed that tryptase can be detected in saliva of children following OFC. Increased levels of tryptase compared to baseline were found if the OFC outcome was positive, suggesting that measuring tryptase in saliva may be useful in the diagnosis of food allergy. Further research is needed to evaluate the potential association between tryptase levels and symptoms.

Investigation of novel salivary biomarkers in paediatric food allergy

“…Recently, we found that tryptase could be detected in saliva samples (by chewing on a synthetic swab) of children that underwent an oral food challenge. 6 Here, we aimed to gain insight into the kinetics of this biomarker and we investigated if salivary histamine can also be detected, now using a different method of saliva collection (passive drooling) which is broadly used in research with salivary biomarkers and is better suitable for children.…”

“…1 As described previously, both challenge days consist of a maximum of seven steps with increasing dose of allergenic protein (starting dose 3 mg, total amount 4443 mg) and 30 min waiting time between each dose. 6 During the placebo day, no food allergen was administered. Symptoms were registered using the scoring system as proposed in a recent publication by Grabenhenrich et al 7 In short, symptoms were divided into five categories (skin, respiratory, gastrointestinal, cardiologic/neurologic and other) and classified as mild, moderate and/or severe.…”

“…All other samples were analyzed for tryptase with ImmunoCAP Tryptase immunoassay on the Phadia250 (Phadia, Uppsala, Sweden) using protocols described in our previous report. 6 All statistical analyses were performed using IBM SPSS Statistics version 25 (IBM, NY, USA). Paired t-test was performed if the variables were normally distributed.…”