Studies of the choroid plexus and its associated epiplexus cells in the lateral ventricles of rats following an exposure to a single non-penetrative blast.

The choroid plexus in rats exhibited ultrastructural changes following a non-penetrative blast. The immunophenotypic features of epiplexus cells associated with the choroid plexus epithelium were also altered. In rats killed at 1 and 7 days after the blast, the intercellular spaces between the epithelial cells were greatly widened, coupled with the massive eruption and possible extrusion of the apical cytoplasm into the ventricular lumen. Associated with these changes was the passage of some monocytes/lymphocytes across the epithelium. The incidence of such a migratory phenomenon was more frequent in rats killed 7 days after the blast. In rats killed 14 days after the blast, the ultrastructural changes of the epithelial cells became less pronounced. At 21 and 28 days after the blast, the ultrastructure of the choroid plexus was comparable to that of normal specimens. The immunoreactivity of epiplexus cells in terms of their cell number and staining intensity with the monoclonal antibodies OX-42, OX-18, OX-6 and ED1 was noticeably augmented at 7 and 14 days after the blast; this, however subsided at 21 and 28 days. It is concluded that the choroid plexus is extremely sensitive to a blast wave as manifested by its structural alterations and the vigorous expression of CR3 receptors and MHC antigens by the epiplexus cells. It is suggested that a possible immune response might have been triggered in the cerebrospinal fluid ventricular system following the blast.