D3.78 - Association between lipocalin sensitization and clinical symptoms: Evidence for cross-reactivity

With over 49% of European households owning a pet and approximately 3.9 million pets in Czechia, furry animals represent a major source of indoor allergens. This widespread exposure results in high sensitization rates and an increased risk of IgE-mediated allergic diseases, including allergic rhinoconjunctivitis, urticaria, and asthma. Lipocalins constitute the largest family of mammalian allergens and include major allergens from dog, horse, cow, rat, and mouse. Despite a highly conserved three-dimensional structure, lipocalins exhibit low amino-acid sequence identity. The aim of our study was to examine the relationship between laboratory-confirmed sensitization to lipocalins and clinical manifestations, providing evidence for clinically relevant cross-reactivity among these molecules.

Molecular diagnostics was performed using the ALEX2 platform (MacroArray Diagnostics, Austria). The study included 101 patients from the Department of Immunology and Allergology, University Hospital in Pilsen, enrolled between 2019 and 2025, with laboratory-confirmed sensitization to a lipocalin (Can f 1, Can f 2, Can f 4, Can f 6, Fel d 4, Fel d 7, Mus m 1, Equ c 1, Cav p 1) or their combinations. Clinical data were retrospectively analyzed with focus on allergic rhinitis, allergic conjunctivitis, skin manifestations (urticaria, eczema), and asthma. Associations between sensitization profiles and clinical symptoms were subsequently assessed.

The most common clinical symptoms were related to exposure to both dog and cat, affecting 70.3% (71/101) of patients, though only 61/71 were laboratory-positive for both animals. Clinical reactivity to cat exposure only was reported by 12.8% (13/101) of patients, most of whom were sensitized to both dog and cat components (mainly Can f 1 and Fel d 7). Symptoms related exclusively to dog exposure were reported by 10.9% (11/101) of patients, with more than half also sensitized to cat or horse molecules, illustrating clinically relevant cross-reactivity between lipocalin allergens. Additional co-sensitizations to other lipocalins were also observed.

Our findings highlight the importance of identifying individual sensitization profiles and clinically relevant cross-reactivity among lipocalin allergens to improve diagnostic accuracy and guide therapeutic strategies. Further research is needed to elucidate the molecular mechanisms of cross-reactivity and their implications for personalized allergy management.