AUTHOR=Balsells-Vives Sara , San Bartolomé Clara , Casas-Saucedo Rocío , Ruano-Zaragoza María , Rius Josefina , Torradeflot Maria , Bartra Joan , Munoz-Cano Rosa , Pascal Mariona 

TITLE=Low Levels Matter: Clinical Relevance of Low Pru p 3 sIgE in Patients With Peach Allergy

JOURNAL=Frontiers in Allergy

VOLUME=3

YEAR=2022

URL=https://www.frontiersin.org/journals/allergy/articles/10.3389/falgy.2022.868267

DOI=10.3389/falgy.2022.868267

ISSN=2673-6101

ABSTRACT=<p>Many clinical lab settings still use 0.35 KU<sub>A</sub>/L as the cut-off for serum specific-IgE (sIgE) immunoassays, while the detection limit is 0.1 KU<sub>A</sub>/L. The clinical relevance of -low-level sIgE (0.1–0.35 KU<sub>A</sub>/L) remains controversial. Pru p 3 sIgE is considered to be the main routine tool for assessing lipid transfer protein (LTP) sensitization. We aimed to evaluate the clinical relevance of Pru p 3 sIgE low levels in a population diagnosed with LTP allergy. Adults diagnosed with LTP allergy and Pru p 3 sIgE ≥ 0.1 KUA/L between 2012 and 2019 were included. Clinical data were reviewed. nPru p 3 basophil activation test (BAT) was performed and basophil reactivity (BR) and sensitivity (BS) correlated with the peach allergy symptoms. Pru p 3 sIgE from 496 subjects was recorded, 114 (23.0%) between 0.1 and 0.34 KU<sub>A</sub>/L (grLOW), the rest ≥ 0.35 KU<sub>A</sub>/L (grB). A total of 44.7% in grLOW and 59.9% in grB were allergic. Urticaria was more frequent in grLOW. In grLOW, Pru p 3 sIgE was higher in patients with local compared with systemic symptoms. In grB, Pru p 3 sIgE was higher in allergic patients. Pru p 3/Total IgE ratios were higher in allergic vs. tolerant in both groups. In BAT, BR was similar in both groups. In grLOW, it was higher on allergic compared with tolerant (<italic>p</italic> = 0.0286), and on those having systemic vs. local symptoms (<italic>p</italic> = 0.0286). BS showed no significant difference between groups. Patients with low levels represent a non-negligible fraction and around 45% are peach allergic. BAT showed functional sIgE in them. Pru p 3 sensitizations should be carefully evaluated even when sIgE levels are low.</p>