We next examined DC phenotypes in the recipient mice. It was noted that a significant increase in the number of pDCs in mice treated with Flt3L or Flt3L with low-dose of Rapa as compared with that of control mice ( Fig. 2A) . Similarly, we also detected a significantly higher proportion of splenic CD8a + DCs in Flt3L or Flt3L/Rapa treated mice ( Fig. 2A) . Since both CD8a + DCs and pDCs have regulatory functions [14] , Our data suggest that Flt3Lcombined with Rapa could induce the expansion of regulatory DCs in the recipient mice.