Preventive sublingual immunotherapy in preschool children: first evidence for safety and pro-tolerogenic effects

Prevention of new IgE sensitizations has been described during allergen-specific immunotherapy. However, prospective data using a preventive approach in very young children who would benefit most are missing. We initiated a prospective pilot study investigating the safety, immunomodulatory, and sensitization-preventive effect of sublingual immunotherapy (SLIT) in mono/oligoclonally sensitized, clinically asymptomatic children 2-5 yr of age.

In this double-blinded, randomized, placebo-controlled pilot study, 31 mono-/oligosensitized children to house-dust mite or grass pollen were included. SLIT with the respective source (n = 15) or placebo (n = 16) was applied. After dose-up-phase therapy was continued for 2 yr. Parents recorded clinical events, vaccinations, and drug intake in a diary. Skin prick testing and specific IgE and IgG measurements were recorded at baseline, 12 and 24 months. At the same time, allergen-specific proliferation and IL10- and TGFβ-dependent Treg function were measured.

Preventive application of SLIT in young children was safe (no relevant side effects in 21,170 single applications). After 12 and 24 months of treatment, the rate of allergen-specific sensitization (specific IgE and SPT reactivity) was comparable in the treatment and the placebo group. However, verum-treated patients displayed a significant up-regulation of allergen-specific IgG (p < 0.05). Furthermore, IL10-dependent inhibition (p < 0.05) was observed in vitro in the treatment group but not in the placebo group.

Preventive SLIT is safe in children 2-5 yr of age and induces regulatory mechanisms involving allergen-specific IgG and IL10. Based on this pilot study, large-scale trials will need to investigate the modulation of sensitization and clinically relevant allergy.