Mast Cell Activation Alterations of Salivary Tryptase (MAAST) Pilot Study

Background: Limited, mostly pediatric, European studies have found salivary tryptase to be consistently undetectable < 0.34 ng/mL at baseline and increased 4-5 minutes after oral food challenges provoking oral symptoms. Objective: The primary aim was to identify if salivary tryptase is present in an asymptomatic North American adult cohort and has diurnal and mastication variation. The secondary aim was to see if salivary tryptase correlates to serum tryptase. Methods: From November 2024 to January 2025, we recruited patients ages 18-64 years and without a carrot allergy, mastocytosis, hereditary alpha tryptasemia, chronic kidney disease, and/or myeloid disorders. Patients underwent nonallergic oral food challenge (NAOFC), chewing ≤ 90 g of carrots in a customary manner for 3 minutes. For each NAOFC, salivary and serum samples were obtained before NAOFC and 4 minutes after NAOFC. Samples were centrifuged and the supernatants were analyzed for tryptase by using a blood test. Results: Nine patients were recruited, with a mean age of 39 years, 88.9% had allergic rhinitis, and 11.1% had a food allergy. All NAOFCs performed did not produce allergic symptoms. Tryptase was detectable in all 36 saliva samples and 36 serum samples. The mean salivary tryptase was 0.52 ng/mL and the mean serum tryptase was 4.80 ng/mL. Diurnal (p = 0.6018) and mastication (p = 0.4964) effects were not associated with salivary tryptase variance. There was no correlation between salivary and serum tryptase (p = 0.0588). Conclusion: Salivary tryptase was detectable at baseline in our adult cohort but had wider variance and discordance compared with serum tryptase. Our study lays the foundation to understand tryptase in saliva as a potential biomarker for local mast cell activation.