Correlation between protein data in normal lumbar CSF and morphological findings of choroid plexus epithelium: a biochemical corroboration of barrier transport via tight junction pores.

Specific "reference areas" were derived from relationships between the proteins prealbumin, albumin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, total transferrin, IgG, IgA, IgM, and the corresponding total protein in normal lumbar CSF samples. The procedure for calculating the boundary lines of these reference areas was carried out on the basis of double standard deviations in subgroups with total protein differences of 50 ml/l within the whole range of 150-400 ml/l CSF. The resulting biochemical data, hydrodynamic radii of the individual proteins investigated, and van Deurs' and Koehler's morphological findings on the existence of pores in the barrier-forming tight junctions of the choroid plexus epithelium could be surprisingly well correlated with one another, although these morphological findings were obtained in choroid plexus of the rat brain. The correlation allowed the conclusion that proteins undergo ultrafiltration via a pattern of tight junction pores with various diameters. However, the molecular mechanism seems to include an additional facilitating component.