Expression of Bcl-2 and Bax in oligodendrogliomas and their relationship to apoptosis

Apoptotic bodies are frequently found in oligodendrogliomas, particularly i n the anaplastic subtype. A range of proteins, such as those of the Ed fami ly, are implicated in the control of apoptosis. The ratio of antagonists of apoptosis, such as Bcl-2, to agonists, such as Bax, is thought to determin e the outcome for a particular cell. This study aimed to determine the expr ession of Bcl-2 and Bar proteins in a series of oligodendrogliomas and to r elate the expression of these to measures of apoptosis. Immunohistochemistr y was used to detect the expression of Bcl-2 and Bar in an archival series of 32 oligodendrogliomas. The results were scored semiquantitatively for th e extent and intensity of tumour staining. Apoptosis indices were determine d by counting apoptotic bodies on haematoxylin and eosin staining and the p ercentage of cells showing a positive reaction with the TdT-mediated dUTP-b iotin nick end-labelling technique (TUNEL). Granular cytoplasmic staining f or Bcl-2 was seen in tumour cells in 81.% of cases. Cases with a strong int ensity (but not extent) of staining showed a lower TUNEL index (P=0.038), B cl-2 expression was identified in the walls of intratumoural blood vessels in 55% of cases and in peri-tumoural neurones (where present) in 87%. Bar e xpression was detected in tumour cells in 69% of cases but no relationship to TI was detected. Bar positivity was seen in blood vessels in 44% of case s and peri-tumoural neurones in 60%. Bcl-2 and Bar were concluded to be exp ressed in a high proportion of oligodendrogliomas, suggesting that they may exert a regulatory role in cell death in these tumours.