Proliferative potentials of meningiomas from 127 patients were examined immunohistochemically using the anti-Ki-67 monoclonal antibody, MIB-1, on paraffin sections, and the correlation among MIB-1 staining index (SI), histopathological finding, and clinical course of the disease was analyzed retrospectively. The mean MIB-1 SI of 50 male patients with meningioma was 5.5%, whereas that of 77 female patients was 2.7%. Higher MIB-1 SI were observed for younger patients. These age- and sex-related differences in MIB-1 SI were statistically significant. The patients were assigned to one of three groups: those with non-recurrent meningioma (n = 73); those with recurrent meningioma in whom the specimens obtained during the initial surgery were used to calculate the MIB-1 SI (n = 21); and those with recurrent meningioma for whom the specimens obtained during the surgery for recurrent tumors were used to calculate the MIB-1 SI (n = 33). The mean MIB-1 SI in these patients were 1.6%, 3.6%, and 8.8%, respectively, and there were statistically significant differences among these three groups. Statistical analyses reveal that meningiomas with a MIB-1 SI of 3% or more have a significantly high tendency for recurrence during the clinical courses, especially within the first 10-year follow-up periods. Moreover, there is statistically significant correlation between MIB-1 SI and recurrence in each Simpson's grade. The time interval to the next recurrence for recurrent meningiomas is associated with the proliferative potential represented by the MIB-1 SI, and a correlation equation has been proposed to predict the date of the next recurrence. Analyses on cellularity of meningiomas revealed no statistically significant difference in cellularity between non-recurrent and recurrent meningiomas. There was no statistically significant relationship between cellularity and MIB-1 SI of meningiomas. In conclusion, examination on proliferative potentials of meningiomas using MIB-1 SI is very important for biological and histopathological analyses and the prediction of future recurrence.

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C o r r e l a t i o n B e t w e e n M I B -1 S t a i n i n g I n d e x a n d t h e I m m u n o r e a c t i v i t y o f p 5 3 P r o t e i n i nR e c u r r e n t a n d N o n -r e c u r r e n t M e n i n g i o m a s Wild type p53 protein has been shown by recent investigations to be involved in the negative regulation of cell proliferation, whereas aberrant p53 protein has lost this negative regulation of cell growth. Wild type pS3 protein, which has a very short half-life, has generally been considered to be undetectable using immunohistochemical methods; however, according to a recent report, wild type p53 protein may accumulate in the nuclei because of a defective ubiquitin pathway. Aberrant pS3 protein has a longer half-life, and thus is visible using immunohistochemical methods. In this study, both the proliferative potential represented by the MIB-1 staining index (SI) and the immunoreactivity of pS3 protein in 51 intracranial meningiomas were studied applying immunohistochemical staining methods to archival paraffin sections.Recurrence of meningiomas is considered to be affected by a variety of clinical, biologic, and histopathologic factors, including the patient's age, sex, tumor location, extent of surgical removal, histopathologic findings, estrogen and progesterone receptors, and receptors for other growth factors. Among these factors, the proliferative potential of meningioma is considered by several investigators to be one of the most important. 1 "" In a previous report, we used an anti-Ki-67 monoclonal antibody, MIB-1, that can detect all proliferative cells in routinely processed paraffin sections, 3,612 and have shown that there is a statistically significant correlation between the MIB-1 staining index (SI) and recurrence of meningi-