Phagocytic properties in tumor astrocytes.

In glioblastoma multiforme (GBM), the pathophysiological events preceding and promoting an uncontrolled and remarkable growth is largely unknown. Studies on gliomas and macrophage expression have shown high levels of phagocytic cells, that is, microglial cells. It has also been demonstrated that human astrocytic cells and rat glioma cells are capable of phagocytosis. The purpose of this study was to investigate a potential phagocytic property in human GBM cells in tumor biopsies from surgery. With an immunhistochemical double staining using macrophage markers (CD68 and CD163) and human telomerase reverse transcriptase (hTERT) as a marker for neoplastic cells, we found high levels of double positive cells in human GBM. In hematoxylin-erythrosin stained sections, we also identified fragmented cell components in the cytoplasm of tumor cells. In our judgement, many neoplastic cells in GBM are also positive for macrophage markers. We suggest that human astroglial tumor cells may have phagocytic properties or phagocyte-like properties. This may represent a latent capacity of self-defence, evoked under certain circumstances. It is likely that these properties substantially help the tumors thrive and expand.