Fig. 1

Baseline characteristics of choroid plexus (ChP) immune cells in naïve CX₃CR-1^GFPmice. First row: Immunofluorescence staining for NKCC1 (apical epithelial marker) in ChP of naïve CX₃CR-1^GFP mice. Numerous green fluorescent protein (GFP)(+) cells were evident within the ChP stroma (located beneath the epithelium, indicated by the yellow arrow), while fewer GFP(+) cells were observed on the ChP epithelium apical surface (epiplexus cells; indicated by the white arrow, scale bar = 20 μm). Second row: Immunofluorescence staining for β-catenin (epithelial marker) in ChP of naïve CX₃CR-1^GFP mice. Numerous green fluorescent protein (GFP)(+) cells were evident within the ChP stroma (located beneath the epithelium, indicated by the yellow arrow), while fewer GFP(+) cells were observed on the ChP epithelium apical surface (epiplexus cells; indicated by the white arrow, scale bar = 20 μm). Third row: Immunofluorescence staining for CD31 (blood vessel marker) in ChP of naïve CX₃CR-1^GFP mice. No GFP(+) cells were detected in the ChP blood vessel. Scale bar = 20 μm. Fourth row: Immunofluorescence staining for Iba-1 in ChP of naïve CX₃CR-1^GFP mice. The white arrow highlights epiplexus GFP(+)/Iba-1(+) cells, the red arrow indicates stromal GFP(+)/Iba-1(+) cells, and the yellow arrow signifies GFP(+)/Iba-1(-) cells (scale bar = 50 μm). Fifth row: Immunofluorescence staining for MHC II in ChP of naïve CX₃CR-1^GFP mice. The yellow arrow indicates stromal GFP(+)/MHC II(+) cells, and the red arrow signifies GFP(+)/MHC II(-) cells (scale bar = 50 μm)