IgE Sensitization to House Dust Mite and Cockroach Allergens in Asthmatic and Allergic Patients in the Tropics

Randy Reina¹Nathalie Acevedo^1,2*Miguel Ángel Caballero¹Isabel Gil²Ramón López Salgueiro^3,4Luis Caraballo¹

• ¹Institute for Immunological Research, University of Cartagena, Cartagena, Colombia
• ²Clinica Respiratoria y de Alergias, Cartagena, Colombia, Cartagena, Colombia
• ³Laboratorio de Diagnóstico Biológico del Servicio de Alergia del Hospital Universitari i Politècnic La Fe, Valencia, Spain
• ⁴Universidad Cardenal Herrera CEU, Valencia, Spain

Introduction: House dust mite (HDM) allergens are major triggers of IgE-mediated asthma in tropical regions, yet the role of cockroach allergens and their cross-reactivity with HDM remains unclear. Cross reactivity among invertebrate allergens is a common challenge in daily practice specially to define primary sensitizers and reactions of clinical relevance. Multiplexed arrays for molecular allergology constitute a useful tool for better detection and interpretation of cross-reactions. Methods: We assessed specific IgE levels and skin prick test reactivity to American cockroach and HDM allergens in cohorts of allergic and asthmatic patients from Cartagena, Colombia, using ImmunoCAP™, skin testing, and multiplex molecular allergology (ALEX2). Results: Cockroach sensitization was present in 29–40% of patients but elicited significantly lower IgE responses and smaller skin test wheals compared to HDM. Most cockroach-sensitized individuals were co-sensitized to HDM, with limited recognition of cockroach molecular components. Mean specific IgE levels to cockroach were 2.1 kU/L ranging from 0.1 to 25.8 kU/L. The majority of patients had IgE levels in class 1 (0.35-0.70 kU/L) or class 2 (0.70-3.5 kU/L). In the ALEX2 array, most cockroach sensitized patients (by skin tests) did not recognize the Periplaneta americana extract (Per a) or other cockroach allergens in the array, and instead they recognized HDM allergens and the extracts of crustaceans and mollusks. Only one patient recognized the Per a extract, cockroach tropomyosin (Per a 7), and tropomyosins in HDM (Blo t 10, Der p 10), shrimp (Pen m 1), and Anisakis simplex (Ani s 3) together with other allergens in crustaceans and mollusks. Interestingly, IgE reactivity to cross-reactive allergens like arginine kinase, myosin light chain, sarcoplasmic calcium-binding protein was not detected. Cockroach sensitization was not associated with worsened asthma control or lung function but correlated with higher shrimp-specific IgE in patients reporting shellfish allergy. Discussion: HDM allergens induce stronger IgE responses than cockroach in this tropical population, indicating HDM as the primary sensitizers. Cockroach sensitization often reflects cross-reactivity and requires careful clinical evaluation to determine its relevance.