Macrophages in experimental and human brain tumors

Abstract

The authors have analyzed 47 tumors of the central nervous system (11 glioblastomas, nine meningiomas, three medulloblastomas, 12 assorted primary neural tumors, and 12 brain metastases) for their content of macrophages. Cell suspensions were prepared by enzymatic digestion and macrophages were quantitated by IgGEAC rosette formation. Adsorption of sensitized indicator cells (EA) to sections of tumor was used as a measure to determine the distribution of IgGFc receptor-positive cells within the tumors and to serve as a control for selective release of IgGFc receptor-positive cells by enzyme digestion. The 11 glioblastomas had a mean macrophage content of 45% (range: 8% to 78%), the nine meningiomas had a mean of 44% (range: 5% to 81%), the three medulloblastomas a mean of 6% (range 2% to 15%), and the metastatic tumors a mean of 24% (range: 4% to 70%). Adsorption of EA demonstrated that IgGFc receptor-positive cells were distributed throughout the tumor mass, although different types of patterns were observed. There was an excellent correlation between the percent of IgGEAC positive cells in suspensions and the extent of EA adsorption to the tumor sections. Compared to systemic neoplasms, most nervous system tumors have a high macrophage content. It is possible that the high macrophage content of brain tumors is related to their immunogenicity, and may be a partial explanation for tha rarity of brain-tumor metastases.

The Impact of Macrophage- and Microglia-Secreted TNFα on Oncolytic HSV-1 Therapy in the Glioblastoma Tumor Microenvironment

“…Similar ranges are seen in human tumors, and these observations underscore the importance of this cell type in the context of oHSV therapy (26, 27). The ability of microglia in the tumor microenvironment to switch from a glioma supportive role to an anti-viral state following oHSV treatment has not been well studied.…”

Lymphoreticular cells in human brain tumours and in normal brain

“…Macrophages have been recently described in both human brain tumours and in chemically induced brain tumours in rats (Lantos, 1975;Morantz et al, 1979). using enzyme-dispersed glioma-cell preparations, found a range of values comparable to those in our series, suggesting that the macrophage numbers in our study were not due to selective release of the macrophages by the dispersal technique.…”

Antibody-Mediated Tumor Cytotoxicity of Microglia

“…In glioblastomas up to 80% of the cells were described to be macrophages [2] derived either from peripheral monocytes or from brain macrophages. A multitude of functions have been as cribed to the residential macrophages of the brain -the microglia -from 'synapse stripping' during central ner vous system (CNS) development to a mediatory role in nerve regeneration and accessory functions in neuroimmune interaction [3].…”