SCIT Demonstrates Superior IgG4 and Treg Induction Versus SLIT in House Dust Mite Allergy, Study Finds
核心洞察
A prospective cohort study found that subcutaneous immunotherapy (SCIT) induced significantly higher serum IgG4 (搜索) levels than sublingual immunotherapy (SLIT) after nine months in HDM-allergic patients.
Both SCIT and SLIT led to significant expansion of regulatory T cells (Tregs) and clinical improvement, with no significant difference in symptom scores between the two routes.
Responders exhibited higher IgG4 (搜索) (median 1050 vs 620 ng/mL) and Treg percentages (7.0% vs 4.8%) compared to non-responders, supporting their utility as biomarkers for treatment response.
A prospective cohort pilot study conducted at Ain Shams University in Cairo, Egypt, has revealed that subcutaneous immunotherapy (SCIT) produces a more robust humoral immune response than sublingual immunotherapy (SLIT) in patients with house dust mite (HDM)-sensitized respiratory allergic disease, despite comparable clinical outcomes between the two routes.
The study, which followed 43 adult patients over nine months, found that SCIT recipients exhibited significantly higher serum total IgG4 (搜索) levels compared with SLIT recipients (p = 0.005). Meanwhile, both treatment modalities led to significant expansion of CD4⁺CD25⁺FoxP3⁺ regulatory T cells (Tregs) and meaningful improvements in asthma and rhinitis control scores.
Immunological modulation across both routes
Investigators measured serum total IgG4 (搜索), total IgE (搜索), and Treg percentages before and after nine months of allergen-specific immunotherapy (AIT). Across the entire cohort, median IgG4 concentrations rose significantly from 320 ng/mL (IQR: 150–600) at baseline to 920 ng/mL (IQR: 540–1400) after treatment (p < 0.001). Total IgE levels showed a mild reduction that did not reach statistical significance (p = 0.112).
On the cellular side, the proportion of CD4⁺CD25⁺FoxP3⁺ T cells increased from a median of 3.4% (IQR: 2.5–4.2) before therapy to 6.3% (IQR: 5.1–7.4) after nine months (p < 0.001), while total CD4⁺ T helper lymphocyte percentages remained stable.
"The lack of significant change in total CD4⁺ T-cell percentages suggests that AIT selectively modulates regulatory subsets rather than inducing broad alterations in T-helper populations," the authors noted, supporting the utility of Treg quantification as a sensitive cellular biomarker for immune tolerance assessment.
SCIT versus SLIT: immunological distinctions
After nine months of treatment, the head-to-head comparison revealed that SCIT induced significantly higher IgG4 (搜索) levels than SLIT (p = 0.005). Treg percentages were also higher in the SCIT group, although this difference approached but did not reach statistical significance (p = 0.058). Total IgE (搜索) concentrations and CD4⁺ T helper cell percentages were comparable between the two groups.
Clinical outcomes, assessed using the Asthma Control Test (ACT) and Rhinitis Control Assessment Test (RCAT), improved in both groups with no significant difference between SCIT and SLIT recipients.
The authors suggested that SCIT may deliver allergen directly to subcutaneous dendritic cells in deep lymphoid compartments, promoting robust T-cell tolerance and humoral isotype switching toward IgG4 (搜索), whereas SLIT primarily engages mucosal dendritic cells and induces local tolerance with slightly weaker systemic responses.
Responder analysis and biomarker performance
Of the 43 patients, 28 (65%) were classified as responders based on at least 20% improvement in ACT or RCAT scores, while 15 (35%) were non-responders. The distribution of SCIT versus SLIT was comparable between the two groups (p = 0.72).
Responders demonstrated significantly higher total IgG4 (搜索) levels (median 1050 ng/mL, IQR 720–1400) compared with non-responders (median 620 ng/mL, IQR 400–910; p = 0.002). Treg percentages were also greater in responders (median 7.0%, IQR 5.5–8.0) than in non-responders (median 4.8%, IQR 3.9–5.5; p < 0.001). Total IgE (搜索) levels were lower in responders (median 145 IU/mL, IQR 110–240) versus non-responders (median 220 IU/mL, IQR 150–350; p = 0.045).
Receiver operating characteristic (ROC) curve analysis demonstrated that serum IgG4 (搜索) levels had good predictive performance for treatment response, with an area under the curve (AUC) of 0.82 (95% CI: 0.69–0.94, p < 0.001). An optimal cutoff of 850 ng/mL yielded a sensitivity of 78% and specificity of 73%. Treg percentages showed an AUC of 0.79 (95% CI: 0.65–0.92, p = 0.002), with a cutoff of 6.0% providing 75% sensitivity and 70% specificity.
Correlations between humoral and cellular markers
Significant positive correlations were observed between total IgG4 (搜索) levels and both ACT scores (r = 0.62, p < 0.001) and RCAT scores (r = 0.58, p = 0.002). Tregs demonstrated a significant positive correlation with IgG4 levels (r = 0.55, p = 0.003) and a significant inverse correlation with total IgE (搜索) levels (r = −0.48, p = 0.010).
These findings reinforce the concept that humoral and cellular biomarkers can serve as objective measures to monitor response and potentially guide personalized immunotherapy strategies.
Study limitations
The authors acknowledged several limitations, including the small sample size, single-center design, and assessment of only total IgG4 (搜索) rather than allergen-specific IgG4. "The observed increase in total IgG4 may not fully represent allergen-specific immunological responses," they cautioned. Additionally, only peripheral blood was assessed, meaning tissue-specific immune responses in the airway mucosa were not captured. The classification of responders based on at least 20% improvement in ACT or RCAT scores was described as an operational definition used for exploratory purposes.
The study was approved by the Institutional Research Ethics Committee of the Faculty of Medicine, Ain Shams University (approval number FMASU MS 665/2023), and all participants provided written informed consent.