Vascular endothelial growth factor expression correlates with tumour gradeand vascularity in gliomas

Aims: Tumour vascularity and vascular endothelial growth factor (VEGF) expr ession were studied in 41 primary brain tumours of astrocytic and oligodend roglial origin, in order to define the potential role of VEGF in the vascul arization and growth of these tumours. Methods and results: Two commercial monoclonal antibodies to the VEGF prote in (from R&D Systems and NeoMarkers), raised against different isoforms. we re utilized. Each monoclonal antibody consistently detected the expression of VEGF in different cell types. The R&D Systems antibody only produced sur face staining of endothelial cells in tumour capillaries, whereas staining with the Neomarkers antibody was largely confined to tumour cell cytoplasm. High levels of staining were seen with the R&D Systems and NeoMarkers anti bodies in 13 and 14 of 15 glioblastomas, respectively, four and three of fi ve oligodendrogliomas, four and seven of 10 anaplastic astrocytomas, one an d three of six low-grade astrocytomas and none and none of five pilocytic a strocytomas. There was a close correlation between VEGF expression. tumour vascularity and grade. Conclusions: These findings support a role for VEGF in the angiogenesis of glioblastoma, anaplastic astrocytoma and oligodendroglioma. The distinct im munoreactivities of the two commercial monoclonal antibodies indicate eithe r there is expression of different splice variants of VEGF or that the epit opes are differentially revealed during synthesis, secretion and receptor-b inding of the growth factor. This highlights the importance of using more t han one antibody in the evaluation of tissue VEGF expression.