Introduction
Allergic rhinitis (AR) is one of the most common chronic respiratory diseases in children worldwide, with a prevalence of 10.80–21.09% in China.1–3 Over the past decade, the prevalence of AR has been rising steadily in Chinese children, making it a significant public health concern.4 House dust mite (HDM), primarily Dermatophagoides pteronyssinus (Der p) and D. farinae (Der f), is the most important indoor aeroallergen, with reported sensitization rates reaching 74.90% and 74.30%, respectively, in AR-affected children across multi-center studies.5
The pathogenesis of AR involves complex interactions among genetic predisposition, environmental exposures, and immune regulation. Male predominance in AR prevalence has been consistently reported, potentially linked to the modulatory effects of sex hormones on Th2-type immune responses and sex-related differences in outdoor exposure patterns.6 The “allergic march” phenomenon is well-recognized in pediatric populations: food allergens (eg, milk, egg white) dominate in early childhood, whereas aeroallergens (eg, HDM, pollens) gradually become the primary sensitizing agents as children grow older.7 Additionally, seasonal variations play an important role in allergen exposure: grass pollens and molds exhibit markedly higher positivity rates during spring and early summer (April to August), whereas HDM acts as a perennial allergen, contributing to year-round symptom persistence with seasonal exacerbations.8
Conventional serum specific IgE (sIgE) testing typically reports mixed or total HDM positivity based on a single cutoff value, which cannot discriminate genuine sensitization to individual HDM components-a critical gap for precision allergen immunotherapy (AIT) selection.9–11 Moreover, the binary reporting of sIgE results obscures the continuous nature of sIgE concentrations, which carry substantially different clinical implications across the sensitization spectrum. Low-grade sensitization (grades 1–3) may represent transient or clinically insignificant sensitization, whereas high-grade sensitization (grades ≥4) is more strongly associated with persistent symptoms, disease severity, and responsiveness to AIT. Despite this, large-scale studies examining the detailed distribution of HDM sIgE sensitization grades across age and sex in pediatric AR populations remain scarce.
In recent years, component-resolved diagnostics (CRD) has become increasingly available in clinical practice, enabling precise identification of major sensitizing molecules and cross-reactive components. Der p 23 has been established as a major HDM allergen,12,13 with positivity rates ranging widely across populations-from 17.20% in some Beijing cohorts14 to over 57.00% in other East Chinese studies.15,16 Importantly, most commercially available HDM AIT extracts are deficient in Der p 23, raising the hypothesis that standard Der p 1/2-based AIT formulations may yield suboptimal efficacy in patients sensitized exclusively to Der p 23;17–19 this hypothesis, however, requires prospective clinical evaluation and does not by itself demonstrate clinical superiority of component-specific or recombinant AIT over conventional extract-based therapy. Meanwhile, Der p 10 (tropomyosin) serves as a cross-reactive allergen between HDM and crustaceans (eg, shrimp, crab), although its positivity rate in HDM-sensitized populations is generally reported below 10.00%.20,21 In the present study, six components were selected to cover the major group 1 and group 2 allergens of both Dermatophagoides species, the chitin-binding major allergen Der p 23 that is underrepresented in commercial extracts, and the cross-reactive allergen Der p 10.
Despite the rapid progress in CRD research, large-scale integrated studies combining comprehensive allergen screening with HDM component-resolved profiling and detailed sIgE grade stratification in Chinese children with AR remain limited. Regional differences, age-specific sensitization patterns, and the clinical implications of unique sensitization profiles (eg, exclusive D. farinae sensitization, exclusive Der p 23 sensitization) are still incompletely understood.22,23 Hangzhou, located in the Yangtze River Delta with a subtropical monsoon climate and high year-round humidity, provides a favorable environment for HDM proliferation and is therefore a suitable setting for studying HDM sensitization in pediatric AR. The two-stage design of this study allowed a large-scale description of the overall allergen spectrum and its demographic distribution (Stage 1), followed by detailed component profiling in a representative random subsample (Stage 2), thereby integrating population-level and molecular-level information at acceptable cost.
This two-stage study was therefore designed to: (1) delineate the overall allergen spectrum in a large cohort of pediatric AR; (2) perform detailed 0–6 grade stratification of D. pteronyssinus sIgE to characterize age- and sex-specific patterns of sensitization intensity; and (3) perform CRD to identify HDM component sensitization profiles, co-sensitization patterns, and their demographic associations, thereby providing a descriptive evidence base for diagnosis and for generating hypotheses on individualized AIT in children with AR.
Methods
Study Design and Participants
This two-stage retrospective cross-sectional study was conducted at the Allergy Clinic of a tertiary children’s hospital in Hangzhou, East China, between January 2025 and December 2025. In Stage 1, a total of 2036 children diagnosed with AR were consecutively enrolled. Inclusion criteria were: (1) diagnosis of AR according to the 2022 Chinese Guidelines for Diagnosis and Treatment of Pediatric Allergic Rhinitis;24 (2) age 1–15 years; (3) no prior allergen immunotherapy; and (4) availability of serum samples for allergen testing.
Exclusion criteria were: (1) use of antihistamines or glucocorticoids within the preceding 2 weeks; and (2) presence of severe autoimmune diseases.
The Stage 1 cohort comprised 1312 boys (64.44%) and 724 girls (35.56%), with a median age of 6.8 years (range 1–15). For age-stratified analyses, children were categorized into four groups: 1–3 years (n=323), 4–6 years (n=725), 7–10 years (n=750), and 11–15 years (n=238). For per-year analyses, data were examined at each year of age from 1 to 15 years.
In Stage 2, from the 894 HDM-positive children identified in Stage 1, 110 were randomly selected using a random number table All 110 children underwent CRD for six HDM components. The Stage 2 cohort comprised 73 boys (66.36%) and 37 girls (33.64%), with a mean age of 7.4±2.8 years (range 1–15). To assess the representativeness of the Stage 2 subsample, we compared the 110 randomly selected children with the remaining 784 HDM-positive children from Stage 1 who were not selected.
No significant differences were observed in sex distribution (66.36% vs 68.24% male, χ2=0.14, P=0.710), age distribution (mean 7.4±2.8 vs 7.2±3.1 years, t=0.62, P=0.535), or the proportion of high-grade sensitization (≥grade 4: 69.09% vs 67.98%, χ2=0.05, P=0.823), confirming that the Stage 2 subsample was representative of the overall HDM-positive population.
The study protocol was approved by the Institutional Review Board of Hangzhou Children’s Hospital (Approval No.: IRB-2026-023 (IIT)). Given the retrospective nature of serum sample analysis and the anonymization of all patient data, the requirement for written informed consent was waived by the ethics committee. All procedures complied with the ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration of 1975, as revised in 2000.
Allergen sIgE Detection (Stage 1)
Serum sIgE levels against 19 allergens-D. pteronyssinus, house dust, cockroach, cat dander, dog dander, Amaranthus, mixed grass pollen, mulberry pollen, mold mix, tree pollen mix, egg white, cow’s milk, beef, shrimp, crab, shellfish, cashew nut, mango, and pineapple-were measured by immunoblot (commercial kit, Zhejiang Diagreat Biotechnology Co., Ltd). The assay was performed according to the manufacturer’s instructions. A cutoff value of ≥0.35 kU/L was considered positive for all allergens.
For D. pteronyssinus-positive samples (sIgE ≥0.35 kU/L), sensitization was further stratified into six grades according to the manufacturer’s standardized classification: grade 1 (0.35–0.69 kU/L), grade 2 (0.70–3.49 kU/L), grade 3 (3.50–17.49 kU/L), grade 4 (17.50–49.99 kU/L), grade 5 (50.00–100.00 kU/L), and grade 6 (>100.00 kU/L). High-grade sensitization was defined a priori as grade ≥4 (≥17.50 kU/L), corresponding to moderate-to-severe sensitization with established clinical relevance. Low-grade sensitization was defined as grades 1–3 (0.35–17.49 kU/L).
Of note, sensitization grades reflect allergen-specific IgE concentrations and should not be equated with clinical disease severity; the relationship between sIgE grade and symptom severity or quality of life was not evaluated in this study, and a positive sIgE test indicates sensitization rather than clinically confirmed allergy.
HDM Component Detection (Stage 2)
Serum sIgE levels against six HDM components-Der p 1, Der p 2, Der f 1, Der f 2, Der p 23, and Der p 10-were measured by immunoblot (commercial kit, Zhejiang Diagreat Biotechnology Co., Ltd). All six component assays used the same cutoff (≥0.35 kU/L) as the primary allergen panel, in accordance with the manufacturer’s specifications. Demographic data (age, sex) and sampling month were recorded for all participants.
All assays were performed and interpreted strictly according to the manufacturer’s instructions, including calibration and internal quality-control procedures. Because this was a retrospective analysis of clinical samples, cross-platform validation against reference methods (eg, ImmunoCAP or ISAC) was not performed; this should be considered when comparing our component positivity rates with studies using other platforms.
Statistical Analysis
Statistical analyses were performed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation (SD). Categorical variables were presented as frequencies and percentages.
Group comparisons were performed using the chi-square (χ2) test or Fisher’s exact test (when expected frequencies in contingency tables were <5). Age trends were analyzed using the Cochran–Armitage test for trend. For multiple comparisons, Bonferroni correction was applied to the ten pre-specified sex comparisons in the sex-difference analysis (α′ = 0.005); all other comparisons (component positivity, age distribution, and sensitization-pattern analyses) were considered exploratory and their results should be interpreted as hypothesis-generating.
Odds ratios (OR) with 95% confidence intervals (CI) were calculated for binary outcomes where applicable, and 95% CIs for prevalence estimates (Table 1 and Table 2) were calculated using the Wilson method. No formal a priori sample size calculation was performed; the precision of subgroup estimates is reflected in the reported CIs (Sample Size Considerations). A two-tailed P value <0.05 was considered statistically significant.
All percentages were reported to two decimal places.Table 1Positivity Rates of 19 Allergens in 2036 Children with ARAllergenPositive CasesPositivity Rate (%)95% CI (%)D. pteronyssinus89443.9141.77–46.07House dust713.492.77–4.38Cockroach401.961.45–2.66Cat dander25412.4811.11–13.98Dog dander24211.8910.55–13.36Amaranthus502.461.87–3.22Mixed grass pollen1738.507.36–9.79Mulberry pollen321.571.12–2.21Mold mix1225.995.04–7.11Tree pollen mix824.033.26–4.97Egg white532.602.00–3.39Cow’s milk53126.0824.22–28.03Beef1366.685.67–7.85Shrimp1296.345.36–7.48Crab1155.654.73–6.74Shellfish231.130.75–1.69Cashew nut472.311.74–3.06Mango150.740.45–1.21Pineapple20.100.03–0.36Table 2Positivity Rates and Sex Distribution of Six HDM ComponentsComponentOverallMale (n=73)Female (n=37)χ2P95% CI (%)Der f 172.73% (80/110)83.56% (61)51.35% (19)12.84<0.00163.74–80.18Der p 170.91% (78/110)80.82% (59)51.35% (19)10.340.00161.83–78.58Der f 264.55% (71/110)72.60% (53)48.65% (18)6.160.01355.25–72.86Der p 262.73% (69/110)71.23% (52)45.95% (17)6.720.00953.41–71.19Der p 2341.82% (46/110)46.58% (34)32.43% (12)2.020.15533.03–51.16Der p 1011.82% (13/110)10.96% (8)13.51% (5)0.150.6987.04–19.18
Sample Size Considerations
No formal a priori sample size calculation was performed for this retrospective study. Stage 1 included all consecutive eligible children (n=2036), providing adequate precision for overall prevalence and age-/sex-stratified estimates. Stage 2 (n=110) was a random subsample of HDM-positive children, selected to enable component-resolved testing within a feasible budget; its representativeness was verified against the remaining Stage 1 HDM-positive population (sex, age, and grade distribution; see Study Design and Participants).
For component positivity rates of 40%–75%, n=110 provides 95% confidence intervals of approximately ±8-9 percentage points. However, small subgroups (eg, the 1–3 years group, n=9) yield wide confidence intervals, and estimates for these subgroups should be interpreted with caution.
Results
Overall Allergen Sensitization Spectrum (Stage 1)
Among the 2036 children with AR, the most prevalent allergen was D. pteronyssinus (43.91%, 894/2036; 95% CI 41.77–46.07%), followed by cow’s milk (26.08%, 531/2036; 95% CI 24.22–28.03%), cat dander (12.48%, 254/2036; 95% CI 11.11–13.98%), dog dander (11.89%, 242/2036; 95% CI 10.55–13.36%), and mixed grass pollen (8.50%, 173/2036; 95% CI 7.36–9.79%). Among food allergens, positivity rates for beef (6.68%, 136/2036), shrimp (6.34%, 129/2036), and crab (5.65%, 115/2036) each exceeded 5.00%. Mold mix showed a positivity rate of 5.99% (122/2036).
All other allergens had positivity rates below 5.00% (Table 1). The detailed age-stratified positivity rates for all 19 allergens are presented in Supplementary Table S1.
Sex Differences in Allergen Sensitization
Among the 2036 children, boys had significantly higher positivity rates than girls for D. pteronyssinus (46.34% vs 39.50%, χ2=9.26, P=0.002), shrimp (7.85% vs 3.59%, χ2=14.68, P<0.001), and crab (6.94% vs 3.31%, χ2=11.56, P<0.001). Cow’s milk (27.90% vs 22.79%, P=0.009) and beef (7.77% vs 4.70%, P=0.008) showed nominally higher rates in boys but did not survive correction. After Bonferroni correction for 10 pre-specified comparisons (α′=0.005), D. pteronyssinus, shrimp, and crab remained statistically significant (Table 3; bolded values).Table 3Sex Differences in Major Allergen Positivity RatesAllergenMale (n=1312)Female (n=724)χ2PP_adj*D. pteronyssinus608 (46.34%)286 (39.50%)9.260.0020.020House dust50 (3.81%)21 (2.90%)1.170.2791.000Cat dander165 (12.58%)89 (12.29%)0.040.8521.000Dog dander168 (12.80%)74 (10.22%)3.120.0770.770Mixed grass pollen119 (9.07%)54 (7.46%)1.580.2081.000Tree pollen61 (4.65%)21 (2.90%)3.630.0570.570Cow’s milk366 (27.90%)165 (22.79%)6.750.0090.090Beef102 (7.77%)34 (4.70%)7.070.0080.080Shrimp103 (7.85%)26 (3.59%)14.68<0.001<0.010Crab91 (6.94%)24 (3.31%)11.56<0.001<0.010Notes: *P_adj: Bonferroni-adjusted P value. *P_adj<0.05 indicates statistical significance after correction for 10 comparisons.
Significant values are shown in bold.
Age Distribution of Allergen Sensitization
Cow’s milk sensitization was most prominent in children aged 1–3 years (1 year: 29.17%, 2 years: 30.85%, 3 years: 27.32%). Egg white sensitization similarly clustered predominantly in the 1–3 years age group. In contrast, aeroallergen sensitization (HDM, pollen, mold) became increasingly evident during the school-age years.
D. pteronyssinus positivity increased progressively with age: from 23.84% in 1–3 years to 53.78% in 11–15 years (P<0.001 for trend). Mixed grass pollen and tree pollen positivity also increased significantly with age (P<0.001 for trend) (Table 4 and Figure 1).Table 4Age-Stratified Positivity Rates of Major Allergens (%)Allergen1–3 Yrs (n=323)4–6 Yrs (n=725)7–10 Yrs (n=750)11–15 Yrs (n=238)P (Trend)D. pteronyssinus23.8440.0053.2053.78<0.001Cow’s milk28.4827.1726.9316.81<0.001Egg white4.334.001.070.84<0.001Mixed grass pollen4.957.599.7312.18<0.001Tree pollen0.934.284.535.88<0.001Figure 1Sensitization rates for selected allergens by age group. D. pteronyssinus (HDM) sensitization progressively increased with age (from 23.84% in 1–3 years to 53.78% in 11–15 years), illustrating the “allergic march”.
Milk and egg white dominated in early childhood, while aeroallergen sensitization rose steadily in school-age children.A line graph showing allergen positivity rate by age group for five allergens.
HDM Sensitization Grade Distribution by Sex and Age
Among the 894 D. pteronyssinus-positive children, boys accounted for 608 cases (68.01%) and girls for 286 cases (31.99%). The proportion of high-grade sensitization (grade ≥4) was 69.08% (420/608; 95% CI 65.30–72.62%) in boys and 66.43% (190/286; 95% CI 60.77–71.66%) in girls, with no statistically significant difference (χ2=0.63, P=0.427). The proportion of grade 6 sensitization (>100 kU/L) was 28.45% (173/608; 95% CI 25.01–32.17%) in boys and 30.07% (86/286; 95% CI 25.05–35.62%) in girls (Table 5).Table 5Distribution of D. pteronyssinus sIgE Grades by SexGradeConcentration (kU/L)Male (n=608)Female (n=286)Total (n=894)10.35–0.6926 (4.28%)9 (3.15%)35 (3.91%)20.70–3.4970 (11.51%)39 (13.64%)109 (12.19%)33.50–17.4992 (15.13%)48 (16.78%)140 (15.66%)417.50–49.99125 (20.56%)54 (18.88%)179 (20.02%)550.00–100.00122 (20.07%)50 (17.48%)172 (19.24%)6>100.00173 (28.45%)86 (30.07%)259 (28.97%)High-grade (≥4)420 (69.08%)190 (66.43%)610 (68.23%)
Age-stratified analysis revealed that in the youngest children (1–3 years), low-grade sensitization (grades 1–3) predominated (53.25%), with only 46.75% (36/77; 95% CI 36.03–57.79%) showing high-grade sensitization. This pattern reversed in the 4–6 years group, where high-grade sensitization rose to 61.38% (178/290; 95% CI 55.66–66.80%). The proportion of high-grade sensitization peaked in the 7–10 years group at 76.94% (307/399; 95% CI 72.56–80.81%), before declining slightly to 69.53% (89/128; 95% CI 61.08–76.84%) in the 11–15 years group (Table 6).Table 6Distribution of D. pteronyssinus sIgE Grades by Age GroupAge GroupnGrade 1Grade 2Grade 3Grade 4Grade 5Grade 6High-Grade (≥4)1-3 yrs778 (10.39%)16 (20.78%)17 (22.08%)15 (19.48%)11 (14.29%)10 (12.99%)36 (46.75%)4-6 yrs29013 (4.48%)44 (15.17%)55 (18.97%)55 (18.97%)47 (16.21%)76 (26.21%)178 (61.38%)7-10 yrs3998 (2.01%)35 (8.77%)49 (12.28%)83 (20.80%)87 (21.80%)137 (34.34%)307 (76.94%)11-15 yrs1286 (4.69%)14 (10.94%)19 (14.84%)26 (20.31%)27 (21.09%)36 (28.13%)89 (69.53%)
Per-year analysis revealed that the proportion of grade 6 sensitization (>100 kU/L) increased from 15.00% at age 3 to 25.51% at age 5 and 34.58% at age 6, representing a relative increase of 130.53% over this 3-year period. The most pronounced single-year increase occurred between ages 5 and 6 (from 25.51% to 34.58%) (Figure 2). These per-year comparisons are cross-sectional; they do not demonstrate that individual children undergo an accelerated increase in sensitization grade during this period (see Discussion).
The detailed distribution of D. pteronyssinus sIgE grades by individual age is presented in Supplementary Table S2. Figure 2Proportion of Grade 6 sensitization (>100 kU/L) by individual age among HDM-positive children. Percentage = (Grade 6 count at that age/HDM-positive count at that age) × 100%.
Data based on 2036 children; positivity defined as sIgE ≥0.35 kU/L. The number of HDM-positive children at each age (denominator) is shown in the revised figure and in Supplementary Table S2. Key transition: Grade 6 proportion increased from 15.00% at age 3 to 25.51% at age 5 and 34.58% at age 6, identifying 5–6 years as a candidate window for high-grade sensitization escalation in cross-sectional analyses.A line graph showing Grade 6 percent among HDM plus children by age in years.
Seasonal Variation of Aeroallergens
Positivity for mixed grass pollen, mold mix, and tree pollen mix exhibited marked increases from April through August. Mixed grass pollen peaked in April (33 cases, 15.49%), May (21 cases, 9.86%), July (26 cases, 12.38%), and August (22 cases, 10.33%). Mold mix formed a modest peak during May–August, with the highest monthly positivity in June (12.05%).
Tree pollen mix was primarily concentrated in April (20 cases, 9.39%) and May (8 cases, 3.76%) (Figure 3). Seasonal differences were statistically significant (P<0.001). Figure 3Seasonal distribution of pollen and mold positivity.
Monthly positivity rates for mixed grass pollen, mold mix, and tree pollen mix among 2036 children with AR. Monthly positivity rate = positive cases in that month/number of children tested in that month × 100%. Mixed grass pollen peaked in April (15.49%) and showed a secondary peak in July (12.38%).
Mold mix peaked in June (12.05%) and remained elevated through September–November. Tree pollen concentrated in April–May (peak 9.39% in April). Seasonal differences were statistically significant (P<0.001).
Hangzhou’s subtropical monsoon climate contributes to perennial HDM exposure with superimposed seasonal aeroallergen peaks.A line graph showing monthly positivity rates for mixed grass pollen, mold mix and tree pollen mix.
HDM Component-Resolved Diagnostics (Stage 2, n=110)
Component Positivity Rates
Among the 110 HDM-positive children, the positivity rates for the six HDM components were: Der f 1 72.73% (80/110; 95% CI 63.74–80.18%), Der p 1 70.91% (78/110; 95% CI 61.83–78.58%), Der f 2 64.55% (71/110; 95% CI 55.25–72.86%), Der p 2 62.73% (69/110; 95% CI 53.41–71.19%), Der p 23 41.82% (46/110; 95% CI 33.03–51.16%), and Der p 10 11.82% (13/110; 95% CI 7.04–19.18%). sIgE levels (positive samples only) showed wide variability, with the highest individual values reaching 948.60 kU/L (Der p 23) and 414.34 kU/L (Der p 1). Component-specific medians and interquartile ranges are presented in Supplementary Table S3.
Gender Distribution
Boys had significantly higher positivity rates for Der f 1 (83.56% vs 51.35%, χ2=12.84, P<0.001; OR 4.82, 95% CI 1.97–11.77), Der p 1 (80.82% vs 51.35%, χ2=10.34, P=0.001; OR 3.99, 95% CI 1.67–9.52), Der p 2 (71.23% vs 45.95%, χ2=6.72, P=0.010; OR 2.91, 95% CI 1.28–6.62), and Der f 2 (72.60% vs 48.65%, χ2=6.16, P=0.013; OR 2.80, 95% CI 1.23–6.38). No statistically significant sex differences were observed for Der p 23 (46.58% vs 32.43%, χ2=2.02, P=0.155) or Der p 10 (10.96% vs 13.51%, χ2=0.15, P=0.698) (Table 2).
Age Distribution
Der p 23 positivity increased markedly with age: 11.11% (1/9) in 1–3 years, 27.50% (11/40) in 4–6 years, 52.38% (22/42) in 7–10 years, and 63.16% (12/19) in 11–15 years (P for trend <0.001). Major components (Der p 1, Der p 2, Der f 1, Der f 2) reached their highest positivity in the 7–10 and 11–15 years groups (80.95–84.21%) (Table 7).Table 7Age-Stratified Positivity Rates of Six HDM ComponentsComponent1–3 Yrs (n=9)4–6 Yrs (n=40)7–10 Yrs (n=42)11–15 Yrs (n=19)P (Trend)Der p 133.33% (3)60.00% (24)83.33% (35)84.21% (16)0.002Der p 233.33% (3)42.50% (17)80.95% (34)78.95% (15)<0.001Der f 133.33% (3)65.00% (26)83.33% (35)84.21% (16)0.004Der f 233.33% (3)47.50% (19)80.95% (34)78.95% (15)<0.001Der p 2311.11% (1)27.50% (11)52.38% (22)63.16% (12)<0.001Der p 1011.11% (1)10.00% (4)14.29% (6)10.53% (2)0.865Note: The 1–3 years group contained only 9 children; age trends for this subgroup should be interpreted with caution.
Co-Sensitization Patterns
Der p 1 and Der f 1 were simultaneously positive in 77 children, accounting for 98.72% (77/78) of Der p 1-positive children and 70.00% (77/110) of the full cohort. Der p 2 and Der f 2 were simultaneously positive in 68 children, accounting for 98.55% (68/69) of Der p 2-positive children and 61.82% of the full cohort. In contrast, Der p 1 and Der p 23 were simultaneously positive in only 42 children (53.85% of Der p 1-positive children; 38.18% overall).
To formally examine whether Der p 23 sensitization was independent of group 1 allergens, we performed a 2×2 association analysis: Der p 1 and Der p 23 positivity were positively associated (Fisher’s exact test P<0.001; OR 8.17, 95% CI 2.62–25.49), indicating partially shared sensitization risk. Nevertheless, 46.15% of Der p 1-positive children were not co-sensitized to Der p 23, and 4 of 46 (8.70%) Der p 23-positive children were Der p 1-negative; thus, Der p 23 sensitization frequently occurs independently of group 1 allergens and would be missed by Der p 1/2-only testing.12,13,25 The overlap among Der p 23, Der p 1, and Der p 2 sensitization is detailed in Supplementary Table S4.
Based on the six-component profiles, the 110 children were categorized into seven sensitization patterns plus a no-component-sensitization group (Table 8). The most common pattern was “classic four-component” (Der f1/2 + Der p1/2 positive, p23 and p10 negative) in 24.55% (27/110), followed by “major components without p10” in 25.45% (28/110). Extensive sensitization (all six components positive) was observed in 6.36% (7/110; 95% CI 3.12–12.56%).
Exclusive D. farinae sensitization occurred in 1 child (0.91%; 95% CI 0.16–4.97%), and exclusive Der p 23 sensitization in 1 child (0.91%; 95% CI 0.16–4.97%). No component sensitization was detected in 21.82% (24/110). The detailed distribution of children across the eight sensitization patterns is summarized in Supplementary Table S5.Table 8Distribution of HDM Component Sensitization PatternsPattern TypeDefinitionCasesProportionExtensive sensitizationAll 6 components positive76.36%Major components (except p10)Der f1/2 + Der p1/2 + p23 positive, p10 negative2825.45%Classic four-componentDer f1/2 + Der p1/2 positive, p23 and p10 negative2724.55%D. farinae-dominantDer f1/2 positive, Der p1/2 partially positive32.73%Exclusive D. farinaeDer f1/2 positive, Der p1/2 negative10.91%Exclusive Der p 23Only p23 positive, major components negative10.91%Other atypical combinationsMixed profiles not fitting above1917.27%No component sensitization detectedAll six components negative2421.82%
Discussion
In this large two-stage study of 2036 children with AR from East China, we confirmed D. pteronyssinus as the predominant aeroallergen, with a positivity rate of 43.91%, consistent with previous reports from China.14,22,23 Beyond confirming this expected finding, our study provides three findings with potential clinical relevance.
Sex Differences: Susceptibility versus Intensity
Detailed 0–6 grade stratification of D. pteronyssinus sIgE revealed that sex differences in HDM sensitization reflect differential susceptibility rather than differential intensity. Boys had significantly higher D. pteronyssinus positivity than girls (46.34% vs 39.50%), consistent with previous epidemiological surveys.6 However, among sensitized children, the proportion of high-grade sensitization (≥4) was virtually identical (69.08% vs 66.43%, P=0.427). This finding refines the conventional understanding of male predominance in AR.
The higher sensitization rates observed in boys may reflect sex-dependent differences in Th2-skewed immune responses modulated by sex hormones, as well as potential differences in outdoor allergen exposure patterns. However, once sensitization is established, the sIgE burden, and thus the potential clinical impact, is comparable between sexes. Clinicians should not assume that HDM-sensitized girls have milder disease simply because they are less likely to be sensitized.
Quantitative sIgE grading should guide risk stratification regardless of sex.
An Age-Associated Pattern of Increasing Sensitization Intensity Around 5–6 Years
We identified a cross-sectional age-associated shift at 5–6 years for the transition from low- to high-grade D. pteronyssinus sensitization. The age-dependent transition from food allergen dominance in early childhood to aeroallergen dominance in later childhood is consistent with the well-established “allergic march”.7 More importantly, the grade-stratified analysis revealed that the age-associated shift from low- to high-grade sensitization was not evenly distributed across age groups but rather clustered around the 5–6 year period. The proportion of grade 6 sensitization (>100 kU/L) increased from 15.00% at age 3 to 25.51% at age 5 and 34.58% at age 6, representing a relative increase of 130.53% over this 3-year period.
These comparisons are cross-sectional and age-associated; they do not demonstrate that individual children undergo accelerated sensitization during this specific period, and longitudinal trajectories may differ across cohorts.
Several hypotheses may explain this population-level pattern. First, this age coincides with a period of immune maturation during which Th2-type responses to aeroallergens may become more readily established. Second, kindergarten or school entry typically increases indoor environmental exposure to HDM.
Third, this period aligns with the well-described transition from food allergen dominance to aeroallergen dominance in the allergic march. However, these mechanistic interpretations remain speculative, as our cross-sectional design cannot distinguish age effects from cohort effects. Longitudinal follow-up studies are needed to confirm whether individual children indeed experience an accelerated increase in sIgE during this age window.26,27
The identification of an age-associated pattern of increasing HDM sensitization intensity has potential clinical implications. It suggests that children who present with AR symptoms at 4–5 years of age may benefit from monitoring of quantitative HDM sIgE levels. If sIgE levels are found to be rising, early environmental control interventions (eg, mite-impermeable bedding covers, air purification, humidity control) may be considered, as this could represent a candidate window for secondary prevention.
For children already confirmed to have high-grade HDM sensitization at this age, earlier evaluation for AIT eligibility may be warranted;18,19 however, prospective studies are needed to determine whether monitoring or earlier AIT evaluation improves long-term outcomes.
Der p 23: A Major Sensitizing Component with Potential Implications for AIT
Component-resolved diagnostics revealed Der p 23 as a major sensitizing molecule (41.82%) with a sensitization profile that was frequently independent of group 1 allergens. The positivity rates for Der f 1 (72.73%) and Der p 1 (70.91%) in our cohort are broadly consistent with previous regional data22,23 but lower than the >90.00% rates reported in some studies,25 which may reflect differences in detection platforms (immunoblot vs protein chip) or population selection. Most notably, our Der p 23 positivity rate (41.82%) is lower than the 55.50–62.50% range cited in some recent studies,15,16 suggesting that Der p 23 prevalence may be more geographically variable than previously appreciated.
Data from Shenzhen and other East Asian populations also show variability in component sensitization rates,16,28 underscoring the importance of regional CRD data. In addition to geographic variability, the lower positivity rate observed in our study may partly reflect methodological differences. Our assay employed an immunoblot platform, whereas many studies reporting higher Der p 23 rates used protein microarray platforms (eg, ImmunoCAP ISAC) or different ELISA formats, which may have higher analytical sensitivity for certain components.29 Therefore, direct comparisons of component positivity rates across studies should account for methodological heterogeneity.
Nonetheless, the extremely high sIgE levels observed for Der p 23 (up to 948.60 kU/L) confirm its importance as a major sensitizing molecule in a substantial subset of patients.
Der p 23, a chitin-binding protein independent of group 1 and group 2 allergens,12,13 showed a positivity rate of 41.82% in our cohort. Our co-sensitization analysis revealed that 46.15% of Der p 1-positive children were not co-sensitized to Der p 23; although Der p 1 and Der p 23 positivity were positively associated overall (OR 8.17, 95% CI 2.62–25.49), this substantial proportion of non-overlap indicates that Der p 23 sensitization is frequently independent of group 1 allergens. Exclusive Der p 23 sensitization was observed in only 0.91% (1/110) of our cohort-lower than the ~5.00% reported in some European real-life studies30-but potentially relevant because most commercial AIT extracts are deficient in Der p 23;17–19 whether this translates into suboptimal AIT responses requires prospective evaluation.
Previous studies have demonstrated that Der p 23-specific IgE responses evolve throughout childhood and are significantly associated with the development of allergic airway disease.27 Additionally, Der p 23 sensitization has been linked to more severe clinical phenotypes and poorer asthma control in pediatric populations.31 These findings suggest that Der p 23 testing may be considered prior to AIT, particularly in regions where Der p 23 sensitization is prevalent; prospective studies are required to determine whether such testing improves AIT outcomes.17–19
Exclusive D. farinae sensitization was identified in only 0.91% (1/110) of children. This suggests that for the vast majority of our cohort, dual-mite or Der p-dominant AIT formulations would be appropriate. However, the existence of even these rare cases underscores the value of CRD in identifying patients who may require species-specific immunotherapy.22 Given the widespread availability of dual-mite products in China, the clinical impact of exclusive D. farinae sensitization may be limited, but CRD remains useful for precision matching in regions where single-species extracts are still used.
Contrary to our initial hypothesis and some prior reports, we found no significant sex difference in Der p 23 sensitization (46.58% vs 32.43%, P=0.155). Instead, we observed significant male predominance for Der p 2, Der f 1, and Der f 2. This novel finding suggests that sex-related immune modulation may differentially affect group 1 and group 2 allergen responses, but not Der p 23.
The biological basis for this component-specific sex disparity warrants further mechanistic investigation.
Beyond the classical Th2 paradigm, non-type 2 inflammatory mediators contribute to allergic airway disease. Interleukin-8 (IL-8/CXCL8), a potent neutrophil chemoattractant, has been implicated in the molecular interplay between allergic rhinitis and chronic rhinosinusitis with nasal polyps,32 indicating that allergen-driven nasal inflammation extends beyond Th2-type responses. Whether HDM component-specific sensitization profiles are associated with IL-8-mediated neutrophilic inflammation in children with AR warrants further investigation.32
Importantly, component-resolved sensitization should not be equated with differential clinical efficacy of component-specific AIT. The present study did not evaluate allergen immunotherapy, treatment response, symptom scores, medication use, or quality of life. Therefore, the observed component sensitization patterns do not demonstrate that recombinant Der p 23 or other single-allergen preparations are clinically superior to standardized whole-mite extracts.
At present, CRD may identify sensitization profiles and generate hypotheses regarding AIT selection; comparative prospective clinical trials are required to establish whether component-based or recombinant AIT provides additional clinical benefit over established extract-based AIT.
Study Limitations
Several limitations of this study should be acknowledged. First, the sample size for component-resolved diagnostics was relatively modest (n=110), and the study was conducted at a single center in East China, which may limit generalizability. Second, we did not perform basophil activation tests or nasal provocation tests to validate the clinical relevance of the identified component sensitization patterns or sIgE grade thresholds.
Third, we did not follow AIT outcomes, so the predictive value of the unique sensitization profiles for AIT response remains to be determined in prospective studies.33,34 Fourth, the 1–3 years group in Stage 2 contained only 9 children, so the trends observed in this age subgroup should be interpreted with caution. Fifth, our cross-sectional design precludes assessment of individual sensitization trajectories. Sixth, we were unable to perform individual-level matching between Der p 10 results and shrimp/crab sIgE data, precluding a formal assessment of tropomyosin-mediated cross-reactivity.
Seventh, sex and age were analyzed separately, and no multivariable regression was performed; unmeasured confounding cannot be excluded. Eighth, no formal a priori sample size calculation was performed, and several subgroup estimates (particularly in Stage 2) have wide confidence intervals. Finally, sIgE positivity indicates sensitization rather than clinically confirmed allergy or disease severity; functional testing (eg, nasal provocation or basophil activation) was not performed, and the clinical significance of the identified sensitization patterns should therefore be interpreted with caution.
Despite these limitations, this study provides regional baseline data on the HDM sensitization profile in Chinese children with AR, integrates grade-stratified intensity analysis with component-resolved profiling, identifies a candidate age-associated window for intervention, and describes the prevalence of Der p 23 sensitization and its frequently independent relationship with group 1 allergens.
Conclusion
House dust mite, with D. pteronyssinus as its predominant representative, is the leading aeroallergen in children with AR in East China. Grade-stratified analysis reveals that boys are more susceptible to D. pteronyssinus sensitization, but sensitization intensity is comparable between sexes once established. Cross-sectional data identified an age-associated increase in the proportion of high-grade sensitization that was most evident around 5–6 years of age.
Component-resolved diagnostics reveals that Der f 1 (72.73%), Der p 1 (70.91%), and Der p 23 (41.82%) are the major sensitizing molecules in our population, with Der p 23 positivity lower than previously estimated in some studies. Co-sensitization between Der p 1 and Der p 23 occurs in about half of Der p 1-positive children, indicating that Der p 23 sensitization is frequently independent of group 1 allergens. Exclusive sensitization to D. farinae (0.91%) or Der p 23 (0.91%) is rare but potentially relevant, as most commercial AIT extracts are deficient in these components.
Given the cross-sectional design and the absence of clinical outcome data, quantitative sIgE grading and CRD may be considered in the clinical evaluation of children with HDM sensitization, but prospective studies are needed to determine whether their use improves AIT selection and treatment outcomes.