Expression of BCL-2 oncoprotein on tumor cells and tumor-infiltrating lymphocytes (TIL) in meningiomas

The Expression of the antiapoptotic oncoprotein BCL-2 and its correlation t o tumor grade in 62 meningiomas (48 classic, 9 atypical, and 5 anaplastic) using single and double immunohistochemistry was investigated. BCL-2 expres sion was found in two different cell populations identified as lymphocytes (BCL-2+CD3+) and tumor cells (BCL+/CD3-). Tumor-infiltrating lymphocytes (T IL) (CD3+) were found within classic (9.5% of cells), atypical (2.4% of cel ls), and anaplastic (1.8% of cells) meningiomas. In classic meningiomas, 66 .5% of TIL were BCL-2 positive, in atypical meningiomas 79.2%, and in anapl astic meningiomas 37.9%. In 33 (68.8%) of the classic meningiomas, medium t o high counts of BCL-2+ tumor cells were detected. Atypical meningiomas sho wed nearly equal percentages of high (two patients), medium (five patients) , and low (two patients) BCL-2+ tumor cell counts, whereas anaplastic menin giomas showed only medium (two patients) and low (three patients) BCL-2 tum or cell counts or were BCL-2-negative (one patient). In summary, a signific ant inverse correlation between the number of BCL-2-positive tumor cells an d tumor grade in meningiomas was found. These findings support the hypothes is of cell survival prolongation by the antiapoptotic ability of BCL-2 prot ooncogenes and demonstrate the prognostic relevance of BCL-2 immunoreactivi ty in meningiomas.