Correlation between IMMULITE-measured grass panel specific immunoglobulin E levels and grass pollen skin-prick test...

Background: Grass pollen represents one of the most common and clinically important groups of aeroallergens. Objective: This study evaluated the correlation between grass panel (GP) specific immunoglobulin E (sIgE) levels measured using the IMMULITE system and skin-prick test (SPT) reactivity in children with asthma or seasonal allergic rhinitis (SAR) and aimed to determine a clinically meaningful optimal cutoff value. Methods: In this single-center retrospective study, children with SAR and/or asthma who had positive GP sIgE results and underwent grass pollen SPT were included. Demographic, clinical, and laboratory data were extracted from medical records, and diagnoses were established according to the GINA and ARIA guidelines. Serum sIgE levels were measured using the IMMULITE 2000 system. The GP sIgE assay includes orchard grass, meadow fescue, perennial ryegrass, timothy grass, and June grass. SPT was performed using Phleum pratense and/or Graminaceae mix-5 extracts, the latter containing orchard grass, meadow fescue, Italian ryegrass, timothy grass, and Kentucky bluegrass. SPT results were classified as reactive or nonreactive, and the optimal cutoff value for GP sIgE was determined. Results: A total of 888 children with positive GP sIgE results who underwent grass pollen SPT were included; 89.3% (n = 793) were SPT-reactive. Of all patients, 649 (73.1%) had SAR alone, whereas 239 (26.9%) had concomitant SAR and asthma. GP sIgE levels were significantly correlated with eosinophil parameters, total IgE levels, and SPT wheal diameters for both extracts. Receiver operating characteristic analysis identified optimal GP sIgE cutoff values of 15.05 kUA/L for overall grass pollen SPT reactivity, 28.2 kUA/L for Phleum pratense, and 20.5 kUA/L for Graminaceae mix-5, each demonstrating clinically useful discriminatory performance. Conclusion: IMMULITE-measured GP sIgE levels were significantly associated with grass pollen SPT reactivity and provided clinically useful information for the assessment of sensitization. Although Graminaceae mix-5 demonstrated greater discriminatory performance than Phleum pratense, both extracts were informative. Mixed extracts may better reflect cross-reactivity, whereas single extracts may complement species-specific assessment and immunotherapy planning. These cutoff values may aid interpretation when SPT cannot be performed.