Allergen immunotherapy (AIT) is the only etiological treatment for allergic rhinitis (AR) patients, yet the impact of allergen sensitization patterns on AIT efficacy remains unclear. This study aimed to assess the effectiveness of subcutaneous immunotherapy (SCIT) using a native house dust mite (HDM) allergen extract in Chinese AR patients with diverse HDM sensitization patterns. This prospective multicenter study across three allergy centers in China enrolled patients aged 5-65 diagnosed with HDM-induced AR. Serum-specific IgE testing for nine HDM components (Der p1, Der p2, Der p23, Der f1, Der f2, Der p5, Der p7, Der p10, Der p21) categorized patients into two groups: Group A with sensitization limited to major allergen components and Group B with sensitization to minor components with or without major components. Both groups underwent 1 year of HDM SCIT (Allergopharma, Germany), whose efficacy was assessed using the visual analogue scale (VAS) and combined symptom medication scores (CSMS). Serum IgE and IgG4 levels against the nine HDM components were measured pre- and post-treatment, and SCIT-related adverse reactions were recorded. The study enrolled 168 patients, with 75 in Group A and 93 in Group B. Group B patients had higher asthma prevalence and elevated baseline HDM sIgE and total IgE levels. After 1 year, Group B showed significantly greater CSMS reduction (67.70% vs. 59.09%, p = 0.03) and VAS improvement (66.67% vs. 50.00%, p = 0.01) compared to Group A. Group A had increased new sensitization risk to minor allergens (Der p5, Der p7, Der p21). No significant difference in SCIT efficacy was observed between patients with and without new sensitization. Both groups exhibited increased sIgG4 levels against all nine HDM allergens, with a more pronounced elevation of sIgG4 levels to Der p21 observed in Group B compared to Group A (p = 0.02). SCIT-related adverse reactions were comparable (p > 0.05). The native HDM allergen extract demonstrates efficacy in Chinese AR patients with varying sensitization patterns. It offers enhanced benefits for patients sensitized to minor allergens with or without major allergens of HDM, positioning it as the preferred option for individuals with AR. Chinese Clinical Trial Registry identifier: ChiCTR2300078642.

Occurrence characteristics and potential associations of mites and microbes in home textile dust across different regional environments in China

Background Allergen immunotherapy (AIT) and biologics such as omalizumab are established treatments for allergic asthma, but long-term data on their combined use are limited. Objective To compare long-term clinical and immunological outcomes of omalizumab, subcutaneous AIT for house dust mite (SCIT-HDM), and their combination in mild-to-moderate allergic asthma. Methods In this prospective, randomized, controlled study, 79 patients with HDM-driven allergic asthma were assigned to omalizumab (A), omalizumab plus SCIT-HDM (B), SCIT-HDM (C), or standard therapy (D). Patients were followed for 36 months. Primary outcomes were changes in inhaled corticosteroid (ICS) dose and annual exacerbations. Secondary outcomes included symptom and medication scores, Asthma Control Test (ACT), asthma quality of life (AQLQ), lung function, remission rates, and biomarkers. Results All groups showed significant reductions in ICS use, with greater reductions in groups A and B than in C and D (p < 0.05). Combination therapy (B) resulted in lower exacerbation rates and reduced oral corticosteroid use compared to other groups. Improvements in ACT, FEV1, and AQLQ were observed across all groups, with more consistent benefits in A and B. Clinical remission occurred most often in group B (47%), followed by A (31%), C (29%), and D (14%). Biomarker changes indicated reduced type 2 inflammation and immunological responses to therapy. No serious adverse events or systemic hypersensitivity reactions were observed. Conclusions Omalizumab, SCIT-HDM, and their combination improved outcomes over 36 months. Combination therapy showed the most consistent benefits, but results should be interpreted cautiously due to the small sample size. Further studies are needed.

House dust mite allergens Der p 1, Der p 2, and Der p 23 are recognized as major clinically relevant allergens worldwide; however, it is difficult to obtain these proteins in purified form from a natural source, which limits their use in molecular targeted immunotherapy and in vivo diagnosis. In this study, we developed and validated robust methodologies for the large-scale purification and individual characterization of native nDer p 1, nDer p 2, and nDer p 23 allergens from the natural sensitization source, Dermatophagoides pteronyssinus. Each allergen was isolated through an independent downstream process based on successive chromatographic steps, achieving high purity and preserving the structural integrity. Molecular standardization was performed in vivo in 27 mite-allergic patients by skin prick testing (SPT), enabling the separate determination of histamine equivalent potency (HEP) values: 7.43 µg/mL for nDer p 1, 8.11 µg/mL for nDer p 2, and 1.55 µg/mL for nDer p 23. These data establish a direct relationship between the protein concentration and biological activity for each major allergen. In conclusion, the successful production and biological standardization of native nDer p 1, nDer p 2, and nDer p 23 proteins provide well-defined reagents for in vivo molecular diagnosis and enable more precise and reproducible standardization compared with complex allergen extracts.

House dust mites (HDM) allergy possesses great clinical and social significance. It is extremely heterogeneous on a molecular level, which poses various difficulties for allergen extract manufacturers, in terms of their composition. Great attention is paid to the concentration of the so-called major allergens, to which most patients are sensitized and due to which, in large, the biological activity of these extracts is expressed. The aim of our study was to conduct a pilot measurement of concentration of three of the most clinically significant major allergens – Der p 1, Der p 2, Der p 23, within 8 series of HDM extracts, produced by the Laboratory of Allergy at Bul Bio – NCIPD using monoclonal antibody ELISA. Results showed the presence of all three major allergens within the extracts, but no statistically proven correlation was found between their concentration, and the reported biological activity of the same extracts from skin prick testing (ρ &lt; 0.20 and p ≥ 0.05).

Pediatric food allergy is a growing health concern, with hen's egg, cow's milk, and wheat being the most common allergens in Japan. The dual allergen exposure hypothesis proposes that early oral intake induces immune tolerance but that cutaneous exposure may promote sensitization. However, little is known about environmental exposure to food allergens before the introduction of complementary foods. This study investigated the presence and concentration of food allergens in the home environments of 3- to 4-month-old infants who had not yet started complementary feeding. Dust samples were collected from 26 households participating in the C-MACH birth cohort study. Allergen concentrations for hen's egg, cow's milk, wheat, peanut, walnut, and house dust mites (Der f 1, Der p 1) were measured using ELISA. Statistical analyses were performed using the Kruskal-Wallis and Steel-Dwass tests. Hen's egg, cow's milk, wheat, and Der f 1 were detected in all samples. Peanut, Der p 1, and walnut occurred in 88%, 81%, and 35% of samples, respectively. Hen's egg, cow's milk, wheat, and peanut allergens were present at significantly higher concentrations than house dust mite allergens. These findings suggest that environmental exposure to food allergens begins prior to oral intake and may contribute to sensitization via the skin. This underscores the importance of considering both dietary and environmental sources in strategies for food allergy prevention. The study provides preliminary evidence of allergen exposure in early infancy and highlights the need for longitudinal research to examine its role in the development of allergic diseases.

House dust mites (HDM) are one of the significant indoor allergen sources which cause IgE-mediated responses in most of the allergic individuals. HDMs are found in human habitats worldwide and Der p 2 is one of the major clinically relevant HDM allergens involved in triggering allergic diseases. The recombinant production of Der p 2 in plant systems provides a cost-effective and viable platform for developing diagnostic kits and allergen-specific immunotherapy. The D. pteronyssinus Der p 2 allergen was transiently expressed in Nicotiana benthamiana and its immunogenicity was evaluated in mice. The Der p 2 coding sequence was cloned into a geminiviral plant expression vector and introduced into N. benthamiana leaves via Agrobacterium tumefaciens-mediated infiltration. Recombinant Der p 2 proteins were purified from the crude extracts and confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot. The immunogenicity of the plant-produced Der p 2 proteins was further evaluated by immunizing mice following a prime-boost immunization regimen, and Der p 2-specific antibody responses were assessed by ELISA. Recombinant Der p 2 was successfully expressed and purified from N. benthamiana, and immunized mice developed high levels of Der p 2-specific IgG antibodies, with antibody titers increased after booster immunization. The results demonstrate that the transient expression of Der p 2 in plants is a feasible and effective strategy for producing immunologically active recombinant allergen proteins for diagnostic and potential clinical applications.

Sensitization to pet dander allergens has been increasing globally, however, its clinical relevance to allergic disease exacerbation remains underexplored. We aimed to determine the prevalence of serum-specific IgE (SSIgE) response to the major dog allergen Canis familiaris 1 (Can f 1), and to evaluate its association with asthma-related symptom severity and exacerbation in a Singapore/Malaysia population. A comprehensive serological profiling of specific IgE responses to 38 common inhalant and seafood allergen sources was performed in 736 young adults from the Singapore/Malaysia Cross-sequential Genetics and Epidemiology Study (SMCGES) sub-cohort. SSIgE levels were analyzed in relation to asthma diagnosis, symptom frequency, and exacerbation history. Detectable Can f 1-specific IgE was present in 13.5% of participants, predominantly at low-grade Class 1-2 levels (0.35-3.49 IU/mL). Individuals with pre-existing sensitization to common inhalant and seafood allergen sources, including house dust mites (HDM), cat dander (Felis domesticus 1, Fel d 1), pollen, fungi, crustaceans, mollusks, and fish, showed a significantly higher rate of Can f 1-specific IgE response. Among asthmatic subjects, elevated Can f 1 SSIgE levels were significantly associated with recent (past 12 months) wheezing (p=0.005), daytime (p=0.019) and nighttime asthma attacks (p=0.033), and asthma exacerbations (p=0.001). These associations remained to be significant and consistent in trend among asthmatic patients sensitized to HDM allergen sources. Sensitization to Can f 1 is associated with increased asthma-related symptom burden and exacerbation risk, particularly in individuals with pre-existing atopy among young adults in Singapore and Malaysia. These findings highlight Can f 1-specific IgE as a potential molecular marker for identifying higher-risk asthma phenotypes in the tropical environment.

Recently, the role of vitamin D in the pathogenesis of asthma and its potential therapeutic value has attracted the attention of researchers. The relationship between vitamin D levels and asthma in children, its clinical manifestations has not been fully studied and some studies have not revealed a clear relationship. Objective. To establish the vitamin D supplementation in children with bronchial asthma. Materials and methods. The cross-sectional study included 80 children aged 6-18 years: 70 with bronchial asthma, 10 apparently healthy (comparison group). All patients underwent a general clinical examination, a study of the function of external respiration using spirometry. Serum concentration of 25(OH)D was determined by ELISA using the «25OH Vitamin D Total ELISA Kit». The study period is May 2024 – February 2025. Results. Deficiency of 25(OH)D was found in 71.4% (CI: 59.2-81.28) of children with bronchial asthma, and in 30% (CI: 8.09-64.63) of cases in the comparison group (p=0.03, χ2=4.99), while vitamin D deficiency was observed only in children with bronchial asthma. The average level of 25(OH)D in the blood serum of patients with bronchial asthma was statistically significantly lower than in children in the comparison group: 21.7 (15.13; 31.43) ng/ml versus 31.95 (26.63; 38.74) ng/ml, p&lt;0.01. In the analyzed cohort, the level of 25(OH)D did not depend on gender, disease duration, age of asthma manifestation and diagnosis, body mass index, family history of allergies and bronchial asthma (p&gt;0.05). Also, the level of 25(OH)D did not depend on the severity of bronchial asthma (p&gt;0.05), but in severe asthma it was statistically significantly lower than in mild asthma (p=0.04). In mild bronchial asthma, the level of 25(OH)D did not differ from the comparison group (p&gt;0.05), while in moderate and severe asthma it was statistically significantly lower than in the comparison group (p&lt;0.01). In patients with controlled bronchial asthma the level of 25(OH)D in the blood serum was higher than in children with uncontrolled asthma (p&lt;0.0001). In children with bronchial asthma and deficiency of 25(OH)D (&lt;30 ng/ml) compared to its sufficient level (&gt;30 ng/ml), there is an increase in the frequency of allergic rhinitis (p&lt;0.001), the frequency of sensitization to allergens of house dust mite (p=0.01), plant pollen (p=0.01), and hairy animals (p=0.04). In patients with bronchial asthma, a significant positive correlation was established between the level of 25(OH)D in the blood serum and spirometry parameters such as vital capacity of the lungs (p&lt;0.0001), FVC (p&lt;0.001), FEV1 (p&lt;0.001); negative – with the level of asthma control (rs=-0.39, p=0.013). Conclusions. This study confirms the relationship between vitamin D deficiency and bronchial asthma, which coincides with global trends. It is advisable to monitor the level of 25(OH)D in the blood serum of children suffering from bronchial asthma. Normalization of vitamin D status as part of complex therapy for bronchial asthma will allow the treatment of 25(OH)D deficiency to be transferred to a qualitatively new, patient-oriented level and to increase the level of control over the disease.

BackgroundHouse dust mite (HDM) allergy involves IgE and TH2 responses to major and minor allergens. Less is known about the involvement of other immune pathways and the potential role of other HDM proteins in allergic disease. In this study, the association between HDM allergy and immune responses to the HDM proteome was investigated.MethodsThe HDM proteome was represented by 40 purified recombinant HDM proteins (19 known allergens and 21 novel proteins). T-cell responses to HDM proteins were determined ex vivo and antibody responses (IgA, IgE, IgG and IgG4) were measured using micro arrays and basophil activation in 21 HDM allergic donors and 16 non-allergic controls. Changes in specific IgE, IgG and IgG4 during SQ HDM SLIT-Tablet immunotherapy was assessed in 38 subjects with allergic asthma.ResultsHDM proteins were broadly immunogenic inducing comparable IgG, IgA, and non-TH2 cytokine responses in both allergic and non-allergic individuals. Specific IgE, IgG4 and TH2 cytokine responses were largely restricted to the allergic donors. IgE and IgG4 were primarily directed to known major allergens and overlapping in specificity whereas cellular TH2 responses extended beyond the known HDM allergens. Individual proteins displayed distinct immunological profiles. HDM sublingual immunotherapy increased the levels of specific IgE and IgG4 but did not change the overall pattern of recognition.ConclusionHDM proteins are highly immunogenic and give rise to complex patterns of immune recognition also in the absence of allergy. This has potential implications for the pathogenesis of HDM allergy and the mode of action of allergy immunotherapy.

Allergic asthma, often triggered by house dust mites (HDMs), is characterized by airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. Among the major HDM allergens, Der pII plays a significant role in promoting inflammation. This study investigates the role of epidermal growth factor receptor (EGFR) inhibitors in modulating Der pII-induced cytokine production and inflammation in human immune cells. Recombinant GST-Der pII protein was expressed and purified for subsequent studies. Human peripheral blood mononuclear cells (HPBMC), THP-1 monocytes, THP-1-derived macrophages, and pulmonary alveolar macrophages (NR8383) were exposed to Der pII, followed by treatment with EGFR inhibitors AZD-9291 and Tarceva. Enzyme-linked immunosorbent assay (ELISA) was used to detect the expressions of IL-6 and IL-8. Nitric oxide (NO) levels were determined using the Griess Reagent System. Der pII significantly induced pro-inflammatory cytokines, including IL-6, IL-8, and TNF-α in HPBMC and THP-1 cells. Both EGFR inhibitors reduced the secretion of IL-6 and IL-8 in these cell types. In THP-1 macrophages, AZD-9291 suppressed IL-6 expression and CD14/CD36 macrophage markers. Moreover, AZD-9291 significantly inhibited NO production in alveolar macrophages. These findings suggest that EGFR plays a critical role in mediating Der pII-induced inflammation, and EGFR inhibitors may represent a potential therapeutic approach for controlling HDM-induced allergic inflammation.

Our previous study demonstrated that laundry detergents induce group 2 innate lymphoid cell-driven eosinophilic airway inflammation by disrupting airway epithelial barriers and promoting IL-33 release, and that detergent residues are present in nearly all household dust. However, their impact on allergen-induced airway inflammation remains unclear. C57BL/6 background mice were intranasally primed four times with ovalbumin (OVA) or house dust mite (HDM) allergens in the presence or absence of a commercial laundry detergent. Following priming, mice were challenged with the same antigen for 3 consecutive days and sacrificed the day after the final challenge. Bronchoalveolar lavage fluid (BALF) and sera were analyzed by ELISA. Lungs were evaluated histologically and analyzed by qPCR. Mice intranasally primed with antigen in the presence of detergent exhibited eosinophilic airway inflammation upon antigen challenge, accompanied by increased IL-5 and IL-13 levels in the BALF. Intranasal administration of detergent and antigen also stimulated antigen-specific IgE production. These detergent- and allergen-induced type 2 responses were significantly suppressed in Il33-/- and Il13-/- mice. Administration of an anti-IL-4 receptor α chain antibody during the challenge phase reduced eosinophil counts in the BALF and antigen-specific IgE levels in the serum. By contrast, anti-IL-33 antibody treatment during the challenge phase did not affect eosinophilic airway inflammation or antigen-specific IgE production. Laundry detergents promote sensitization to co-inhaled allergens and exacerbate eosinophilic airway inflammation and antigen-specific IgE responses via IL-33 and IL-13. These findings suggest that detergents can act as adjuvants that facilitate airway sensitization.

In China, therapeutic options are limited by the narrow availability of allergen preparations, with house dust mite (HDM) allergen immunotherapy (AIT) as the main choice for most patients. However, polysensitization is highly prevalent, and the benefit of HDM AIT in such patients remains uncertain. The study aims to evaluate the effectiveness of single-allergen HDM AIT on both perennial and coexisting allergen-specific symptoms in polysensitised allergic rhinitis (AR) patients and to explore predictors of treatment response. We performed a multicenter retrospective cohort study including 81 patients with AR who were polysensitised to HDM and at least one other inhalant allergen (e.g., pollens, mould or animal dander). All participants received HDM subcutaneous immunotherapy (SCIT) for 12 to 36 months. Baseline characteristics, including serum allergen-specific IgE (sIgE) levels and comorbidities, were collected. Symptom severity was assessed using the Visual Analog Scale (VAS), and treatment response was defined as a ≥ 30% reduction in VAS scores from baseline. Statistical comparisons between responders and non-responders were conducted using Fisher's exact test for categorical variables and Mann-Whitney U tests for continuous data. Firth logistic regression was used to identify predictors of treatment response. The overall response rate for perennial symptoms was 68.8%, and varied in patients with co-existing allergies: 72.7% for moulds, 70.0% for animal dander, 65.5% for tree pollen, 70.2% for weed pollens. Allergen-specific symptom response rates varied across allergens: 68.2% for moulds, 30.0% for animal dander, 56.7% for tree pollens, 74.5% for weed pollens. Higher sIgE levels to HDM and mould were significantly associated with lower response rates in patients co-sensitised to both. A predictive model incorporating both sIgEs showed good specificity. Single-allergen HDM AIT is effective in many polysensitised AR patients; however, its efficacy varies by coexisting allergen type and sIgE level. Patients co-sensitised to mould with high HDM and mould sIgE appeared to have poorer outcomes. These preliminary findings require confirmation in larger prospective studies to guide tailored AIT strategies.

Ginsenoside Rg3 alleviates allergic rhinitis by regulating NLRP3-mediated inflammatory response and pyroptosis through SIRT6.

Atopic dermatitis (AD) in infants is associated with increased risk of developing other allergic diseases, including asthma. This progression is known as atopic march (AM). We established a murine AM model by first inducing AD-like skin inflammation to house dust mite (HDM) allergen. Mice were subsequently challenged with HDM delivered to the lung. Our data show that epicutaneous sensitization with HDM increased serum IgE, ear thickness, and immune cell infiltration into the skin, accompanied by an increase in CD4+ tissue-resident memory T cells (Trm) in the lung. Following pulmonary HDM challenge, eosinophil influx and T2 inflammation were increased in the lung. Together, our data suggest communication between the skin and lung, where allergen sensitization on the skin increases lung Trm and amplifies the T2 allergic response to lung allergen challenge. This clinically relevant model could help identify novel targets for local interventions to reduce the progression of AD to asthma.

The mechanisms of airway allergen sensing and type 2 immune response initiation remain poorly understood. Using a mouse house dust mite (HDM)-induced allergic airway model, we identify a population of lung macrophages located close to alveolar capillaries that express Ly6G and the nuclear receptor Nr4a1/Nur77. These atypical Ly6G+Nur77+ macrophages preferentially capture airway-delivered allergens and play an important role in initiating HDM-driven T helper type 2 (Th2) responses. They sense the major HDM allergen, the cysteine protease Der p 1, via protease-activated receptor 2 (PAR2), and their activation and accumulation require both PAR2 and Nr4a1/Nur77. These Ly6G+Nur77+ macrophages regulate the migration of conventional migratory dendritic cells (mDCs) to draining mediastinal lymph nodes (mLNs) through cysteinyl leukotriene (CysLT) production, which enhances mDC migration toward CCL21 for T cell priming. Inhibiting CysLT biosynthesis reduces mDC migration and dampens Th2 allergic responses, highlighting possible therapeutic avenues in type 2 immunity.

Allergic diseases are increasingly recognized as a worldwide public health problem, affecting countries at all levels of economic growth. In recent years, it has been proposed that allergic diseases result from excessive type 2 inflammation, which is driven by cooperative interactions between the innate and acquired immune systems. In this model, allergens, pathogen-associated molecular patterns (PAMPs), and proteases would all be considered allergen-associated substances. In this study, the Japanese ceder allergen Cry j1 and the house dust mite (HDM) allergen Der f1 were selected as representative allergens; lipoteichoic acid (LTA) from Staphylococcus aureus as a PAMP; and V8 protease (V8) from S. aureus, fungal Alternaria extract (Alt), and HDM fecal extract Dff as proteases. The effects of ozone gas on these substances were investigated in terms of allergenicity, proinflammatory activity via innate immunity, and protease activity. Ozone gas inactivated the allergenicity of both Cry j1 and Der f1, and the protease activities of V8, Alt, and Dff, in a CT value (the product of concentration [C] and exposure time [T])-dependent manner. The proinflammatory activity of LTA via innate immunity was significantly inactivated after ozone exposure (301 ppm·min). Although this study was carried out in a small chamber at the basic research level, the results suggest that ozone gas can inactivate indoor allergy-related substances and may help alleviate allergic symptoms. With appropriate safety measures, such as using it in a closed system, this technology has great potential for practical application to allergy management.

Allergen-specific immunotherapy with Der p 1/2 mRNA vaccines relieves house-dust-mite-induced allergic airway inflammation in a mouse model.

89 children, median age 6.76±3.7 of three different regions of residence (the Siberian Region, the South Region and the Central Moscow Region) were included in the study. All ENT-specialists of the research had otolaryngic allergy training. All patients had otolaryngic examination and nasal endoscopy. The atopic status was confirmed either by means of blood sIgE >0.35 kU/l or by skin prick testing. The sensitizations to 6 group of aeroallergens such as tree pollen, grass pollen, weed pollen, molds, house dust mite and epidermal allergens were analyzed and compared among regional ENT-groups. Statistical analysis was performed using SPSS Statistics v.23.0. Among all regions ENT-visits in Siberia were statistically significant in case of grass pollen sensitization (χ2 Pearson=5.159, p=0.023). In the South Region sensitization to house dust mite (χ2 Pearson=5.463, p=0.019) and to tree pollen (χ2 Pearson=6.016, p=0.014) were statistically significant for ENT-visits. ENT-visits in the Central Moscow Region were significant in case of house dust mite sensitization (χ2 Pearson=7.875, p=0.005). The children with such ENT-pathology as otitis media were more often sensitized to weed pollen (χ2 Pearson=3.949, p=0.047). Throat pathology i.e. tonsillar hypertrophy according to the ENT examination was more often in patients with tree pollen sensitization (χ2 Pearson=6.075, p=0.014). ENT-pathology in patients with pediatric allergic rhinitis could be different and needs further investigation.

House dust mite (HDM) allergy significantly impacts quality of life. Allergen immunotherapy (AIT), specifically sublingual immunotherapy (SLIT), is an effective treatment for HDM allergy, but adherence to SLIT remains a challenge. This study aimed to evaluate the impact of adherence to SLIT on the use of allergy medications, including antihistamines, nasal corticosteroids, and inhaled corticosteroids (ICS) in a real-world setting. We conducted a nationwide cohort study using data from Denmark's comprehensive registries. Patients who initiated HDM SLIT between 2015 and 2020 were included, with follow-up through 2022. Adherent patients, defined as those obtaining at least 80% of the prescribed Defined Daily Dose (DDD) of SLIT, were compared to non-adherent patients. Medication use was tracked for antihistamines, nasal corticosteroids, and ICS. Statistical analyses, including Probit and generalised linear models, assessed the likelihood of obtaining medications and the quantity dispensed, adjusted for age and sex. Of 950 patients, 456 (48%) were classified as adherent. Adherent patients showed significantly reduced usage of antihistamines (p < 0.001) and nasal corticosteroids (p < 0.001) compared to non-adherent patients. No significant differences were found in ICS use or dosage. Additionally, adherent patients were more likely to have higher education levels and be married or cohabiting. Adherence to SLIT for HDM allergy is associated with reduced use of antihistamines and nasal corticosteroids. These findings emphasise the importance of SLIT adherence in managing HDM allergy and suggest that improving adherence could further reduce medication usage, improving patient outcomes in real-world settings.