Ultrastructural and immunohistological evidence for dendritic-like cells within human choroid plexus epithelium.

Ultrasonic examination of human choroid plexus (CP) disclosed the presence of a possibly new type of CP cells displaying many of the features of dendritic cells and apparently expressing HLA Class II antigens. These cells bear long processes, devoid of tight junctions, inserted between CP epithelial cells, and have close contacts with CP basement membrane. They could, therefore, play a key role in immunosurveillance in the central nervous system.