Severe food allergy reactions are associated with α-tryptase

Background: Increased TPSAB1 copy numbers encoding ⍺-tryptase are associated with severe reactions in adults with Hymenoptera venom allergy, systemic mastocytosis, and idiopathic anaphylaxis. Objective: The primary objective was to assess the association between ⍺-tryptase and severity of food allergy. Methods: A total of 119 subjects underwent tryptase genotyping; 82 of them were from an observational food allergy cohort at the National Institute of Allergy and Infectious Disease (NIAID), and 37 were from a cohort of children who reacted to peanut oral food challenge (OFC) at Lurie Children's Hospital of Chicago. The primary predictor was presence or absence of ⍺-tryptase. The primary outcomes for both cohorts were measures of severity of food allergy reaction. Secondary outcomes included OFC symptom scores (Bock/Practical Allergy [PRACTALL] and Severity Grading Score for Acute Reactions [SGSAR]). Correlation between total α-tryptase isoforms and OFC scores was also assessed to account for gene dosage effects. Results: Among the subjects in the NIAID cohort, the presence of ⍺-tryptase was associated with a higher prevalence of food-triggered anaphylaxis than in those with only β-tryptase (P =.026). Similarly, only 1 of 6 subjects in the OFC cohort with only β-tryptase (17%) had a severe reaction, whereas 20 of 31 of subjects with α-tryptase (65%) had a severe reaction (P =.066). Subjects with ⍺-tryptase also had higher total SGSAR scores than did the subjects with no ⍺-tryptase (P =.003). In addition, there were also significant positive correlations between ⍺-tryptase isoform copy numbers and both higher total SGSAR and Bock/PRACTALL OFC scores (P =.008 and P =.003, respectively). Conclusion: The presence of α-tryptase in subjects is correlated with a higher prevalence of anaphylaxis or severe reaction to food than in subjects without any α-tryptase.