A preventive approach to allergen immunotherapy may help alter the course of allergy development in young children. Researchers report that house dust mite sublingual immunotherapy, or HDM-SLIT, induced protective immune responses in sensitised preschool children before the onset of allergy symptoms.
The randomised trial enrolled children aged 3 to 5 years who were sensitised to house dust mite allergens but had not yet developed clinical allergic disease. Conducted between 2017 and 2022, the study compared daily HDM-SLIT with placebo over two years. Children who received more than four months of therapy were included in the final analysis.
By the end of treatment, children treated with HDM-SLIT showed significantly increased Der p 1-specific IgG levels compared with placebo, suggesting a strong immunomodulatory effect. The treatment also increased levels of HDM-specific IgG1 and IgG4 antibodies, which are thought to block allergic reactions. Researchers found no sustained increase in allergen-specific IgE levels, indicating treatment did not worsen allergic sensitisation.
Additional analyses demonstrated reduced skin and basophil reactivity to house dust mite allergens among children receiving SLIT. The therapy also appeared to limit the development of new sensitisations during the study period. Functional testing showed that serum from treated participants could inhibit basophil activation, providing evidence that the induced antibodies had biologically relevant blocking activity.
The authors concluded that preventive HDM-SLIT can induce early immune changes associated with allergy protection before symptoms arise. They suggest early intervention in sensitised, high-risk children could potentially interrupt progression to allergic disease, although larger studies are needed to confirm long-term clinical benefit.