Grass and Tree Allergen Components Specific IgE Assay on the NOVEOS™ Immunoanalyzer:
Evaluation of Inter-method Comparison
Liao, C., Sinson, E., Raymundo, M., Blay, M., Rodems, K.
Research and Development, Hycor Biomedical, Garden Grove, CA
Background: IgE sensitization to pollen allergens affect up to 30% of the industrialized
population and continues to increase due to the intensifying pollen season. The current in vitro
diagnostic method for pollen sensitization involves the utilization of crude allergen extracts.
These extracts contain extensive pollen cross-sensitization, cross-reactive carbohydrate
determinants (CCD), and other non-allergenic molecules that may deter from accurately
determining the symptom-eliciting pollen source. However, molecular-based testing, which
utilizes recombinant allergen components, can address the issues of crude extracts and provide
more effective immunotherapy strategies. This study evaluates the performance of grass and
tree components on the NOVEOS™ Immunoanalyzer assessing inter-method comparison.
Methods: A total of 107 patients sensitized to at least one of the components found in grasses
and trees were tested on the NOVEOS Immunoanalyzer and Phadia 1000 System against grass
(rPhl p 1, rPhl p 5b, rPhl p 7, rPhl p 12), birch (rBet v 1, rBet v 2), and olive (rOle e 1)
components. In addition, a panel of 10 negatives patients for each component were also tested.
Results: The overall agreement between the two systems was 95% (Cohen’s kappa = 0.89; 95%
confidence interval [CI] 0.80 – 0.99) with positive linear correlation (r2 from 0.72 to 0.99, and
Spearman’s rho from 0.79 to 0.97) across all components. With the exception of rPhl p 12,
Passing-Bablock regression analysis resulted slopes from 0.74 (95% [CI] 0.61 – 1.05) to 1.16
(95% [CI] 0.88 – 1.52). rPhl p 12 resulted a slope of 1.94 (95% [CI] 1.47 – 3.12), indicating a
higher sensitivity with the NOVEOS sIgE assay. 10 discordant patients (ImmunoCAP positive,
NOVEOS negative) were observed, of which 6 had sufficient volume to test for anti-CCD IgE
reactivity. All 6 patients were confirmed to be positive for anti-CCD IgE. Patients with anti-CCD
IgE antibody may show falsely elevated results on the ImmunoCAP sIgE assays, which employs a
cellulose-based matrix that can contain CCD epitopes, despite using recombinant components.
Disregarding CCD positive patients, the overall agreement between the two systems improves
to 98% (Cohen’s kappa = 0.96; 95% [CI] 0.89 to 1.02).
Conclusion: The NOVEOS Immunoanalyzer capably detects sIgE to grass and tree allergen
components and provides a strong agreement with ImmunoCAP sIgE assays not demonstrating
CCD interference.
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