Background: Vascular endothelial growth factor (VEGF)-A and VEGF receptor expression in the peritumoral brain zone (PBZ) differs from that in the tumor core (TC) of glioblastoma. To date, no comparative study has investigated the expression of immunosuppressive cells in the PBZ and TC of glioblastoma. Methods: In 10 patients with newly diagnosed glioblastoma, we used immunohistochemistry to analyze the expression of VEGF-A, hypoxia-inducible factor-1α, programmed cell death-1 (PD-1), Foxp3, CD163, CD4, and CD8 to assess the immunosuppressive microenvironment. Results: The number of Foxp3+ and CD163+ cells was significantly greater in the TC than in the PBZ and correlated with greater expression of hypoxia-inducible factor-1α and VEGF-A in the TC than in the PBZ. The number of CD8+ T cells was lower in the TC than in the PBZ, and the TC had more PD-1+CD8+ T cells compared with the PBZ. These results suggest that the hypoxic condition could be associated with PD-1 expression on lymphocytes, the distribution of Foxp3+ regulatory T cells and CD163+ tumor-associated macrophages. Conclusions: The present study reports the first clinicopathologic features of the differences in immunosuppressive cells and the expression of immune checkpoint molecules between the TC and PBZ of glioblastoma.
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