Immunohistological localization of the anti-encephalitogenic bovine spinal cord protein (BSCP) in axons

The localization of the anti-encephalitogenic bovine spinal cord protein (BSCP) in sections of bovine peripheral nerve was studied by the indirect immunofluorescence technique using the globulin fraction of a rabbit anti-BSCP serum and fluorescein isothiocyanate-conjugated goat anti-rabbit IgG. BSCP was clearly demonstrated in axons and in the endoneurial space surrounding the myelinated nerve fibres but was not detected in myelin or in the perineurial connective tissue. The precise localization of BSCP in the spaces encompassing the myelin sheaths is hindered by the inadequate visualization of the unstained sites by immunofluorescence. However, since anti-BSCP antibodies do not react with collagen or blood vessels, the major components of the endoneurial space, it is highly probable that BSCP is localized in Schwann cells. Myelin-free axons prepared from bovine midbrain stained evenly throughout their entire lengths indicating that BSCP was also a component of CNS axons.