Scope
LTP‐syndrome is characterized by sensitization (IgE) to multiple non‐specific lipid transfer proteins (nsLTPs) with a variable clinical outcome. The treatment is primarily based on offending ...food avoidance. However, the determination of Pru p 3‐specific IgE is currently the main diagnostic tool to assess sensitization to nsLTPs. Herein, the study evaluates improvement of LTP‐syndrome diagnosis and clinical management using a new IgE multiplex‐immunoblot assay with a high diversity of food nsLTPs.
Methods and results
An EUROLINE‐LTP strip with 28 recombinant nsLTPs from 18 allergenic sources is designed. In total the study investigates 38 patients with LTP‐syndrome and compares results from the nsLTPs (LTP‐strip) with the respective food extracts of Prick‐by‐prick (PbP) testing. The agreement exceeds 70% for most nsLTPs, e.g., Pru p 3 (100%), Mal d 3 (97%), Pru av 3 (89%), Pha v 3 isoforms (87%/84%), Ara h 9 (82%), Cor a 8 (82%), and Jug r 3 (82%). The functionality and allergenic relevance of nine recombinant nsLTPs are proven by Basophil activation testing (BAT).
Conclusions
The new IgE multiplex‐immunoblot nsLTP assay shows a good diagnostic performance allowing culprit food assessment. Negative results from LTP‐strip may indicate potentially tolerable foods, improving diet intervention and patients’ quality of life.
The multiparameter‐immunoblot assay containing a high diversity of plant‐food‐nsLTPs shows a good diagnostic performance compared to Prick‐by‐Prick, representing an opportunity to improve the LTP‐syndrome allergological work‐up and clinical management. True positive tests allow culprit food assessment while true negatives may provide potentially tolerable foods, improving diet intervention and patient quality of life.
Many clinical lab settings still use 0.35 KU
A
/L as the cut-off for serum specific-IgE (sIgE) immunoassays, while the detection limit is 0.1 KU
A
/L. The clinical relevance of -low-level sIgE ...(0.1–0.35 KU
A
/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
A
/L (grLOW), the rest ≥ 0.35 KU
A
/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 (
p
= 0.0286), and on those having systemic vs. local symptoms (
p
= 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.
