Clinical and immunologic effects of long-term sublingual immunotherapy in asthmatic children sensitized to mites: a double-blind, placebo-controlled study

Background: Immunotherapy through local routes is thought to be a valuable therapeutic option for respiratory allergy. We investigated the clinical ef ficacy and immunologic effects of sublingual immunotherapy (SLIT) in asthma tic children with mite-induced respiratory allergy. Methods: Twenty-four patients (age range 8-15 years), suffering from mild t o moderate asthma, with single sensitization to mite allergen, were enrolle d. After a 1-year observation phase, patients were randomly allocated to on e of two groups, and were given SLIT (sublingual-spit) as drops for 2 years according to a double-blind, placebo-controlled (DBPC) design. Symptoms/me dication scores (diary card), visual analog scale, and immunologic paramete rs (house-dust-mite [HDM]-specific IgE, and total HDM-specific IgG and IgG4 ) were determined during the observation phase and during the DBPC treatmen t period. Results: Twenty-one patients completed the study. At the beginning of the t reatment, no difference in environmental allergenic pressure could be shown between the groups. After 2 years of therapy, there was a significant decr ease ill asthmatic symptoms (P = 0.0001) and medication use (P = 0.0001) in the active group compared to the placebo group. The visual analog score on overall asthma symptoms improved in the SLIT group (P = 0.0001), but not i n the placebo group. Nevertheless, the immunologic results did not show sig nificant differences in HDM-specific IgE and total HDM-specific IgG or IgG4 between the active and placebo groups (P = NS). No relevant side-effects w ere recorded throughout the study. Conclusions: Our results suggest that treatment for 2 years with SLIT is cl inically safe and effective in significantly decreasing respiratory symptom s in children with mild to moderate asthma sensitized to HDM. On the other hand, the lack of changes of the immunologic parameters calls for further i nvestigations with special reference to kinetics and mechanism(s) of action of this mode of treatment.