Non-contact co-culture of confluent endothelial monolayers with rat astrocytes for 5 days reduced monolayer permeability to albumin compared to the permeability of monolayers cultured alone (P<0.0001, n=4). Non-contact co-culture with monocyte-derived dendritic cells (MoDC) for 5 days also reduced permeability (P=0.0002, n=7) but non-contact co-culture with undifferentiated monocytes was without effect (P = 0.7552; n=7). Exposure of monolayers to MoDC-conditioned medium for 5 days reduced permeability compared to exposure to cytokine-supplemented medium (P<0.0001, n=3). *P <0.05, **P<0.01, ***P<0.001.