Dendritic cells (DCs) uptake soluble antigens and large volumes of fluid through macropinocytosis and migrate for antigen presentation. Aquaporin 3 (AQP3), a water and glycerol transporting protein, is highly expressed in immature DCs. To elucidate the role of AQP3 in DC function, we investigated subtype and activation of DCs in AQP3 knock-out (AQP3(-/-)) mice. Depletion of AQP3 did not affect the development of bone marrow-derived DCs (BM-DCs) by GM-CSF or the Flt3 ligand and the level of expression of CD86 on unstimulated and LPS-stimulated BM-DCs. In addition, the percentage of CD86(+) cells among splenic cDCs after LPS treatment in both in vitro and in vivo conditions was similar in wild type and AQP3(-/-) mice. However, the frequency of CD4(+) cDCs in the spleen of AQP3(-/-) mice was significantly lower than that of wild type mice. There was higher expression of CD103 in the CD8(+) subpopulation of splenic cDCs from AQP3(-/-) mice than wild type mice. In the dermis, more CD103-expressing cells were detected in AQP3(-/-) mice than in wild type mice and the LPS-induced decrease of CD103(+) dermal DCs was impaired in AQP3(-/-) mice. AQP3 depletion did not affect the uptake of either albumin or dextran by CD11c(+) splenic DCs. However, HgCl(2), which is an AQP inhibitor, significantly inhibited the uptake of albumin but not dextran by CD11c(+) splenic DCs. These results suggest that AQP3 may play a role in modulating DC population and migration.