Frontiers in Bioscience-Elite (FBE) is published by IMR Press from Volume 13 Issue 2 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
*Author to whom correspondence should be addressed.
Academic Editor: Charanjit Kaur
Tumour associated macrophages (TAMs) are increasingly recognized as supporters of tumour growth. The present study was undertaken to examine benign pilocytic astrocytomas (PAs) for the presence of M2 macrophages. We have asked the question whether TAMs in PAs share the predominant CD163 immunophenotype with tumour-associated microglia/macrophages of malignant gliomas. In addition, we were interested in the question whether there is evidence that the macrophages in PAs derive from resident microglia in surrounding normal brain or whether cells expressing a macrophage phenotype may invade PAs from the vasculature. The latter question is of great interest with regard to so-called "bone marrow-derived microglia" (BMDM) which may provide a physiological route of entry into the CNS that could be used for novel cell-based treatments of brain cancer. In fact, we have found strong morphological evidence for such macrophage recruitment into PAs. We propose therefore that PAs may be used as a model for the study of macrophage recruitment into gliomas. Importantly, our results also confirm that microglia/macrophage infiltration per se is not associated with malignant glioma behaviour.