Prognostic significance of microvessel density determined by an anti-CD105/endoglin monoclonal antibody in astrocytic tumors: Comparison with an anti-CD31 monoclonal antibody

There are conflicting reports as to whether the degree of angiogenesis as measured by microvessel density (MVD) has a prognostic value in astrocytic tumors. This may be due to the use of different antibodies against endothelial cells to highlight microvessels. It has been reported that unlike pan-endothelial antibodies, such as CD31, anti-CD105 antibodies preferentially react with endothelial cells in angiogenic tissues. To clarify the validity of anti-CD105 antibody in the evaluation of angiogenesis, we assessed MVD using an anti-CD105 monoclonal antibody (mAb) (CD105-MVD) and an anti-CD31 mAb (CD31-MVD) in a series of 50 astrocytic tumors, and correlated MVD with expression of the key angiogenic factor vascular endothelial growth factor (VEGF) and prognosis. The mean CD31-MVD and CD105-MVD was 36.7 and 24.8 for low-grade astrocytoma (LGA), 48.0 and 42.7 for anaplastic astrocytoma, 55.3 and 51.9 for glioblastoma multiforme (GBM), respectively. CD105-MVD was more closely correlated with VEGF expression than CD31-MVD. Patients with LGA and GBM showing higher CD105-MVD had a significantly shorter mean survival time (MST) than those with lower CD105-MVD tumors (P = 0.0381 and 0.0131, respectively). Whereas the MST of patients with higher CD31-MVD tumors seemed to be shorter than that of lower CD31-MVD patients within each tumor grade, the differences were not statistically significant. These findings suggest that anti-CD105 mAb may be a better marker than anti-CD31 mAb in evaluation of angiogenesis and prediction of prognosis in astrocytic tumors.