539:
Tryptase Levels Following Systemic Reactions Associated with Immunotherapy
Sunday, March 4, 2018
South Hall A2 (Convention Center)
Sofia Szari, MD, Edward Champoux, MD, Christopher A. Coop, MD, Priscilla H. Wong, MD, Tonya S. Rans, MD, Howard C. Crisp, MD FAAAAI
RATIONALE: Elevations in serum tryptase have been used to support the diagnosis of anaphylaxis, but not in the setting of promptly recognized systemic reactions (SRs) to subcutaneous immunotherapy (SCIT). We hypothesized that tryptase levels could provide data helpful for assessing the ambiguous symptoms of SRs to SCIT.

METHODS: Twenty-two adult patients with SRs while receiving SCIT were recruited from July 2014 through June 2017. The patients were in build-up or maintenance phase to aeroallergens and venom, but were excluded if the SR occurred during a cluster protocol. The severity of the reaction was graded according to the World Allergy Organization (WAO) SCIT SR Grading System. Total tryptase was obtained from stable patients between 1-2 hours post-reaction. A second baseline tryptase level was drawn 2-60 days post reaction. Tryptase was measured using an immunofluorimetric assay (ImmunoCAP, Phadia, Uppsala, Sweden).

RESULTS: Two patients had reaction: baseline tryptase ratios ≥ 1.5, with values 15.8:4.4 and 6.3:4.2. Only 1 patient had a reaction tryptase > 10ug/L, with a tryptase of 15.8ug/L. Among the 21 other patients, the reaction tryptase ranged from 1.9-6.5 ug/L. Of the 22 patients, 12 returned for baseline tryptase levels, which ranged from 2.9-5.7 ug/L. Severity ranged from 1-2 based on the WAO SCIT SR Grading System.

CONCLUSIONS: Despite elevated tryptase levels being a marker of anaphylaxis to field reactions, it does not appear to reliably rise within the 1-2hrs following the first sign of SRs in SCIT. Potentially due to these SRs being mild in nature or being treated promptly with epinephrine.