Early Fel d 1-specific T-cell activation was followed by full T-cell unresponsiveness to allergen after 1year in the MAT-Fel d 1 group , characterized by increased allergen-specific T regulatory cells , decreased circulating Fel d 1 tetramer-positive cells , increased IL-10 and FOXP3 expression , and change in the HR2/HR1 ratio toward HR2 .