Antibodies to neurofilament, glial filament, and fibroblast intermediate filament proteins bind to different cell types of the nervous system.

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Abstract
Antisera were raised to the 210,000 dalton and the 49,000 dalton proteins of a fraction enriched in intermediate (10 nm) filaments from human brain. Proteins of the filament preparation were separated by SDS[sodium dodecyl sulfate]-polyacrylamide gel electrophoresis and used for immunization and subsequent analysis of the reactions of the sera by rocket immunoelectrophoresis. Anti-210,000 dalton serum precipitated proteins of MW 210,000, 160,000 and 68,000 and reacted with all the neurofilament triplet components. Anti-49,000 dalton serum did not react with the triplet proteins but precipitated the 49,000 dalton protein. By immunofluorescence on tissue sections, anti-210,000 dalton serum bound to neuronal axons in sciatic nerve and cerebellum. In dissociated cell cultures, rat dorsal root ganglion cells and their processes bound the serum, whereas nonneuronal cells did not. Some cultured cerebellar neurons were also positive, whereas astrocytes were not. At the ultrastructural level, anti-210,000 dalton serum bound to intermediate filaments inside axonal processes. Anti-49,000 dalton serum bound to astrocytes in sections of the cerebellum and cultured astrocytes had filaments that stained, whereas other cell types did not. In sciatic nerve sections, elements stained with this serum, but cultured cells from newborn sciatic nerve were negative. An antiserum against the 58,000 dalton protein of the cytoskeleton of NIL-8 fibroblasts strongly stained sciatic nerve sections, binding to Schwann cells but not to axons or to myelin. In cerebellar sections, astrocytes were positive, as were blood vessels and cells in the pia. In cell cultures, anti-58,000 dalton serum stained filaments inside Schwann cells, fibroblasts and astrocytes, but neurons were negative. Cells in the cultures and tissue sections of the nervous system failed to react with antiserum to the 58,000 dalton protein of skin intermediate filaments. In these studies, astrocytes in vivo and in culture were the only cells which had antigens related to 2 classes of intermediate filaments.