House dust mite sensitization shapes the clinical expression of shellfish allergy

SUMMARY

Background. Cross-reactivity among phylogenetically distant invertebrates—such as mites, crustaceans, and mollusks—is mainly driven by conserved panallergens including tropomyosin, arginine kinase, and troponin C. However, the clinical impact and molecular basis of these cross-reactivities remain incompletely defined. Methods. A multicenter observational study was conducted in 3,777 patients reactive to at least one arthropod or invertebrate allergen component. Serum IgE profiles were assessed using the ALEX²® multiplex platform, including allergens from mites, crustaceans, mollusks, and related taxa. Clinical data were analyzed according to molecular sensitization patterns. Results: Mite sensitization was detected in nearly 80% of patients, 80% of whom showed co-sensitization to other invertebrates. Sensitization to mollusks and/or crustaceans occurred in 31.9% (n = 1,207), with a marked predominance of concomitant mite sensitization (79.1% for crustaceans, 60.3% for mollusks). Clinically relevant shellfish reactions were reported in > 95% of patients co-sensitized to mites and shellfish allergens but were uncommon among those mono-sensitized to decapod or mollusk components. Tropomyosin-specific IgE was detected in > 95% of symptomatic individuals and was significantly associated with moderate-to-severe reactions (p < 0.001). Conclusions. Mite–shellfish co-sensitization defines the major molecular and clinical phenotype of shellfish allergy, supporting a model in which mite-derived tropomyosin acts as the primary sensitizer enabling cross-reactivity to homologous invertebrate proteins. In contrast, isolated shellfish sensitization rarely results in symptoms. Component-resolved diagnostics are crucial to identify at-risk patients and to avoid unnecessary dietary restrictions.

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