The Identification of Proliferating Cells in Nervous System Neoplasms by Use of the Monoclonal Antibody Ki-67

In an estimate of the proliferative potential of nervous system neoplasms in 100 adult patients, the proliferating cells (G1, S, G2, and M phases) were demonstrated immunohistochemically by means of the monoclonal antibody Ki-67. The percentage of cycling cells was calculated in immunostained frozen sections by the peroxidase-antiperoxidase method. The histologic grade and known biologic behavior of gliomas were reflected in the percentages of stained cells, which ranged from 0.3% in a pilocytic astrocytoma to 17.2% in a glioblastoma multiforme. All three cases in which stained cells constituted over 20% were metastatic carcinoma. The percentage of stained cells in pituitary adenomas showed a wider range (0.2-3.7%) than that of the S-phase fraction obtained by Nagashima et al. (0.1-1.5%). These results indicate that Ki-67 staining is technically suitable as a routine method of estimating the proliferating cell fraction of nervous system neoplasms, and this information may be useful in predicting their biologic behavior.