Thirty-eight children completed the study. At T1 all had rhinitis and 34 also had asthma. At T3, 30 patients had improved, six experienced no changes and two worsened. Improvement was associated to FEV1/FVC and VAS improvement; to a reduction in D. pteronyssinus skin prick test; to a progressive increase in serum levels of D. pteronyssinus IgE, and D. pteronyssinus, Der p1 and Der p2 IgG4. IL-10 levels showed an early increase at T2f (the end of initial build-up immunotherapy phase), and then a reduction at T3 (the end of a year of immunotherapy). Improvement associated to an early increase in IL-10 and was correlated with VAS and specific IgG4 evolution.