MIB-1 immunostaining and DNA flow cytometry in meningiomas

The correlation between S- and G2/M-phase fractions and MIB-1 index in meningiomas was investigated. Flow cytometric analyses were performed on cell suspensions from 81 samples of paraffin-embedded tissue from 29 patients with a total of 28 meningiomas and 1 hemangiopericytoma using the modified Hedley's method. Sections from the paraffin-embedded tissues were stained with anti-MIB-1 monoclonal antibody after microwave oven processing. Five hundreds cells were scored. Correlations between data were estimated using linear regression. DNA aneuploidy was present in 4/29 tumors. Mean S- and G2/M-phase fractions in the 25 nonrecurrent tumors were 1.77 and 4.76%, and in the recurrent tumors were 2.41 and 5.81%, respectively. The proliferative index (PI = S + G2/M fraction) was 6.52% in the nonrecurrent tumors and 8.29% in the recurrent tumors. The mean MIB-1 score in the nonrecurrent tumors was 1.25% and in the recurrent tumors was 2.69%. There was a linear correlation between percentage of S-phase fraction or PI and the MIB-1 score. Both methods are useful to assess the proliferative activity in meningioma.