Sublingual immunotherapy (SLI) is effective for treating patients with respiratory allergies but the underlying immunological mechanisms remain unknown. We evaluated the immunological changes induced by subcutaneous immunotherapy (SCI) and SLI in children with allergic respiratory disease sensitized to Dermatophagoides pteronyssinus.

Group 1 (N=15) was treated with SCI and Group 2 (N=13) with SLI (ALK Abello) before (T0), one month (T1) and one year (T2) after starting immunotherapy. Total and specific IgE were determined by immunoassay and lymphocyte subsets, activation markers and intracellular cytokines by flow-cytometry.

At T1 a significant increase in the CD4 subpopulation and monocytes, with a decrease in B lymphocytes was detected in Group 1. In both groups there was a significant increase in activated CD4, a decrease in activated CD8 cells, and a decrease in cytokine production (IFN-γ, TNF-⍺, IL-2, IL-4, IL-10 and IL-13), although only significant for IL-2 and TNF-⍺ in the CD4 subpopulation. Although these changes were maintained at T2, there was also a significant decrease in IL-10, IL-13 and IL-4. No changes in total or specific IgE antibodies were found in either group.

Both types of immunotherapy induce very similar immunological changes, even immediately after administration. The relationship between these changes and the clinical symptoms needs to be established.