EXPRESSION OF 300-KILODALTON INTERMEDIATE FILAMENT-ASSOCIATED PROTEINDISTINGUISHES HUMAN GLIOMA-CELLS FROM NORMAL ASTROCYTES

The availability of biochemical markers to distinguish glioma cells fr om normal astrocytes would have enormous diagnostic value. Such marker s also may be of value in studying the basic biology of human astrocyt omas. The vimentin-binding, 300-kDa intermediate filament (IF)-associa ted protein (IFAP-300kDa) has recently been shown to be developmentall y expressed in radial glia of the central nervous system of the rat. I t is not detected in the normal or reactive astrocytes of the adult ra t nor in neonatal rat brain astrocytes in primary culture. In the pres ent study, double-label immunofluorescence microscopy using antibodies to IFAP-300kDa and glial fibrillary acidic protein (GFAP, an astrocyt e-specific IF structural protein) identifies this IFAP in GFAP-contain ing tumor cells from examples of all three major types of human astroc ytomas (i.e., well-differentiated, anaplastic, and glioblastoma multif orme). Astrocytoma cells in primary cultures prepared from all three a strocytomas also express this protein. It is not detectable in normal adult brain tissue. Immunoblot analyses using the IFAP-300kDa antibody confirm the presence of a 300-kDa polypeptide in fresh astrocytoma pr eparations enriched for IF proteins. These results suggest the utility of IFAP-300kDa as a marker for identification of human glioma cells b oth in vitro and in situ.