Ihara F, et al. - This study was designed to clarify which Th2 cell subsets are important in house dust mite-induced allergic rhinitis (AR) [(HDM-AR)], the influence of sublingual immunotherapy (SLIT) on the pathogenic Th2 cells, and the association of Th2 cell subsets with SLIT efficacy. The possible usefulness of allergen-reactive ST2⁺CD45RO⁺CD4⁺ cells or those combined with IL-5⁺IL-13⁺CD27^-CD161⁺CD4⁺ cells as markers was suggested. This finding was indicative of the successful treatment of SLIT. Furthermore, it was suggested that these cells may play a crucial role in the pathogenesis of AR as pathogenic memory Th2 cells.