D3.107 - Comparison of Cupressaceae sensitization allergens in a large Spanish cohort

Cupressaceae pollen is a major allergen source in Southern Europe, yet different extract-based specific IgE (sIgE) assays may vary in the allergenic material they contain and in their susceptibility to cross-reactivity. To better understand real-world performance, we compared several commonly used allergens for Cupressaceae sensitization (T222 - Cupressus arizonica, T23 - Cupressus sempervirens, T6 - Juniperus sabinoides, and T226 - nCup a 1) in a large Spanish cohort.

We retrospectively analyzed sIgE results for >28 000 subjects. Agreement among allergens was examined using standard analytical comparisons and categorical concordance at two commonly used clinical thresholds (0.1 kU/l and 0.35 kU/l). We also evaluated how these assays behaved across different geographic regions and explored whether a single test could provide similar diagnostic information to current multi-step reflex strategies employing component-resolved diagnostics.

Across the cohort, the three extract assays (T222, T23, T6) showed high qualitative agreement, particularly at the higher clinical cutoff, where overall concordance exceeded 90% in most comparisons. Regional patterns were largely consistent, with only minor variations attributable to sample size or local exposure profiles. T226 demonstrated consistently high concordance and only modest incremental detection as second-line to all three extract assays, indicating limited added clinical value as a reflex test. Importantly, the extract assay T23 aligned closely with the combination of T222 and T226 results, matching their joint classification in the large majority of samples, while the proportion of T222-only signals unsupported by the component test was small. This suggests that T23 may capture the clinically relevant sensitization pattern typically revealed through multi-step testing, but in a single measurement.

In this large real-world dataset, the allergen extract assays demonstrated strong concordance, and the component test added limited incremental information. Although additional clinical evaluation may be warranted, these findings suggest that T23 Cupressus sempervirens may offer a practical and streamlined alternative to multi-step testing algorithms for assessing Cupressaceae sensitization in the Mediterranean regions.