RESUMEN
Glial fibrillary acidic protein (GFAP), vimentin (Vi) and cytokeratin (CK) intermediate filament (IF) proteins were studied in glioblastoma cell line GL-15. The immunofluorescence staining revealed strong positive staining for vimentin in all cultured cells. Approximately 20% of analyzed cells showed strong and 50% moderate intensity of staining for GFAP. About 3% of all cells were positively stained with a mixture of anti-CK monoclonal antibodies. The expression of all IF was not in relation to the cell density or days in vitro after passage. The double immunofluoresce revealed that all CK-positive cells express GFAP and vimentin. This study demonstrates the heterogeneity of the clonal GL-15 glioma cell line which consists in three immunocytochemically distinct cell types: Vi+/GFAP-/CK-, Vi+/GFAP+/CK-, and Vi+/GFAP+/CK+. These findings give further evidence about the expression of non-glial IF in cultured glioma cells.