Identification of specifically reduced memory Th2 cell subsets in HDM-induced allergic rhinitis patients after sublingual immunotherapy

RATIONALE: The sublingual immunotherapy (SLIT) is expected to allow changes to the underlying pathogenesis of allergic rhinitis (AR). However, which Th2 cell subsets are affected by SLIT, the association of Th2 cell subsets with SLIT efficacy have not been fully clarified.

METHODS: The cytokine production and frequency of house dust mite (HDM)-specific T cell subsets in peripheral blood mononuclear cells (PBMCs) were evaluated using flow cytometry in 89 HDM-AR patients (HDM allergen 300 IR dose: n=46, placebo: n=43) who participated in a placebo-controlled study of SLIT with HDM tablets. All patients provided samples both before treatment as a baseline and at the end of the 52-week study. The PBMCs were stained with CellTrace™ Violet (CTV) before culture with HDM extract, and HDM-specific T cells were detected as the proliferated cells with diminished CTV.

RESULTS: HDM-specific IL-5- and IL-13-producing CD27^-CD161⁺CD4⁺ cells and HDM-specific ST2⁺CD45RO⁺CD4⁺ cells were observed in the peripheral blood from each patient with HDM-AR; these cells significantly decreased after SLIT in the group treated with active tablets, and they associated with the clinical efficacy of SLIT.

CONCLUSIONS: The results suggest that allergen-specific IL-5⁺IL-13⁺CD27⁻CD161⁺CD4⁺ cells and ST2⁺CD45RO⁺CD4⁺ cells may be useful as SLIT biomarkers; the results also support a potentially critical role for these cells in the pathogenesis of AR.