Proliferative assessment of GFAP-positive and GFAP-negative glioma cells by nucleolar organizer region staining.

The proliferative potential of two types of tumor cells that did or did not express glial fibrillary acidic protein (GFAP) in 19 cases of high-grade gliomas, including nine anaplastic astrocytomas (WHO criteria, grade 3) and 10 glioblastoma multiforme (grade 4), was investigated by a combined staining technique, one-step silver colloid method for nucleolar organizer region-associated argyrophilic protein (Ag-NOR) and immunocytochemistry for GFAP. The mean numbers of Ag-NORs in GFAP-positive cells and GFAP-negative cells of high-grade gliomas were 2.68 and 3.74, respectively. The value of GFAP-negative cells was significantly greater than that of GFAP-positive cells (p less than 0.01). Our results show that, by means of the immunocytochemistry for GFAP, tumor cells in human high-grade gliomas can be divided into two groups expressing GFAP or not, and that the mean number of Ag-NORs of GFAP-negative cells is more representative of the degree of histological malignancy than that of positive cells. It is considered that the proliferative assessment of GFAP-negative tumor cells in high-grade gliomas by combined staining of Ag-NOR silver staining and GFAP immunocytochemistry is useful for understanding the histological malignancy of high-grade gliomas.