D1.55 - Monosensitization to Der p 23 in house dust mite allergy in daily clinical practice in a county of Gipuzkoa, Basque Country, Spain: a retrospective and descriptive analysis

House dust mite (HDM) allergy is a leading cause of allergic rhinoconjunctivitis and asthma. Der p 23 has been recognized among the major HDM allergens clinically relevant, with monosensitization reported in 4%-5% of HDM–allergic patients. Our aim was to describe the epidemiological, demographic and clinical characteristics, and sensitization profile in patients with HDM allergy and Der p 23 monosensitization in Tolosaldea. 

We conducted a retrospective and descriptive study of 365 patients with HDM allergy at the Allergy Department, between 2023 and 2025. The inclusion criteria were: history of perennial allergic symptoms; positive skin prick test (SPT) to D pteronyssinus (wheal ≥3 mm); sIgE to total extract of D pteronyssinus ≥0.35 kUA/L; and sIgE to Der p 1 and Der p 2 ≤0.35 kUA/L and to Der p 23 ≥0.35 kUA/L (ImmunoCAP, Thermo Fisher Scientific). Sensitization to minor allergens was not available. Statistical tests were used for the association of variables. 

A total of 16 patients were monosensitized to Der p 23, representing a prevalence of 4.38% (16/365). The median age was 43 years (23-57 years) and 56,3% were females.  All patients had allergic rhinitis which was moderate in 60% (9/16) of the sample. Additionally, 25% (4/16) had asthma, which was mild-persistent in all cases. As cosensitizations detected by SPT or sIgE; 60% corresponded to L destructor, 44% to dog dander, 25% to cat dander and 10% to A alternata. None cosensitizations were detected in 18.8% (3/16).

Laboratory test are shown in the Table. The sIgE Der p 23/sIgE D pteronyssinus ratio was 60%. Allergen-specific immunotherapy with D pteronyssinus was prescribed in 31% of patients (5/16) with no adverse reactions.

Our prevalence of monosensitization to Der p 23 in HDM allergy is similar to other Spanish series, as is the prevalence of asthma. The study needs to be expanded to determine sensitization to minor allergens in order to avoid a possible misclassification of monosensitization status based on ImmunoCAP alone.