Dermatophagoides farinae‐specific immunoglobulin epsilon reactivity in an immunoglobulin epsilon‐selected subset of self‐reported allergic participants from Ilocos Norte, Philippines: An exploratory study

Background: Dermatophagoides farinae (Df ) is a major source of over 30 allergens that elicit allergic sensitization in atopic individuals. Despite its global significance, limited data exist on its allergenic relevance among a subset of Filipinos. Objectives: This study aimed to characterize the sensitization profile of a subset of Filipino allergic participants with elevated total immunoglobulin epsilon (IgE) (≥100 IU/mL) and to evaluate the associations between Df -specific IgE levels and demographic variables. An exploratory assessment of recombinant Der f 1 (rDer f 1) was also performed in a subset of samples. Methods: Plasma samples were obtained from participants with self-reported allergic asthma (AA), allergic rhinitis (AR), and/or atopic dermatitis (AD) (n = 690) and participants without self-reported allergies (n = 270), totaling 960 participants. Cases included participants with self-reported AA, AR, and/or AD and a total IgE level of ≥100 IU/mL, which served as a secondary screening criterion, resulting in 169 cases. Controls included participants without self-reported allergies and with a total IgE level of <100 IU/mL, resulting in 77 controls. Selected samples were analyzed for Df -specific IgE. rDer f 1-specific IgE enzyme-linked immunosorbent assay (ELISA) was performed in a subset (n = 90; 45 cases and 45 controls), while inhibition ELISA was conducted in 5 selected samples. Associations between Df -specific IgE positivity and demographic variables were assessed using Pearson correlation. Results: Allergic cases exhibited significantly higher mean total IgE levels (220.36 IU) than nonallergic controls (38.95 IU; P < 0.0001). Among allergic samples, 78.70% (133/169) were sensitized to Df , and all Df -positive samples (45/45) reacted to the rDer f 1 allergen. Df -specific IgE levels correlated significantly with allergy diagnosis ( P = 0.002), smoking status ( P = 0.004), and family history of atopy ( P = 0.040). Pre-absorption with rDer f 1 resulted in mean inhibition of 17% and maximum inhibition of 47% of IgE reactivity to Df extract. Conclusion: Df represents a clinically relevant allergen source within the subset of Filipino allergic patients, with rDer f 1 contributing to IgE reactivity among samples tested. These results suggest potential value in incorporating Df into diagnostic evaluation and future therapeutic considerations. Moreover, the findings remain exploratory and are constrained by limited sample size and study design.