Abstract 3323:In situmultiplex analysis of resident microglia and infiltrating macrophages in glioblastoma

Glioblastoma mutliforme (GBM) is the most malignant primary brain tumor. Resident microglia and peripheral infiltrating macrophages account for up to half of the non-neoplastic cells in a GBM. These tumor-associated macrophages have been implicated in proliferation, angiogenesis, and immunosuppression in GBM and can influence the efficacy of chemo-, radio-, and immunotherapies. However, certain cancer specific interactions have been associated with either microglia or macrophages, necessitating an approach that can delineate the two populations. Multiplex immunofluorescence offers a technical advantage that allows for the profound phenotyping of cells in the tumor microenvironment as well as their spatial organization. We have designed a multiplex immunofluorescence protocol to differentiate microglia and infiltrating M1/M2 macrophages in GBM in situ. Human GBM tissues were investigated with a multiplex panel consisting of GFAP, TMEM119, CD68, c-maf, and CD163. After multi-spectral acquisition, the microglia and macrophage populations could be easily phenotyped and localized in all of the tissues examined. Microglia and peripherally recruited M1 and M2 macrophages were quantified. The spatial distribution of the populations within the tumor core, edge, or margin was evaluated. The approach presented here demonstrates the power of multiplex immunohistochemistry in the phenotyping and spatial analysis of resident and recruited immune cell populations on a single tissue section and the potential application of this method in clinical studies. Citation Format: Nicolas Goulange, Amanda Finan-Marchi, Maroua Tliba, Manon Motte, Fanny Estermann, Alexandre Vernay, Jean-Philippe Coton, Renaud Burrer. In situ multiplex analysis of resident microglia and infiltrating macrophages in glioblastoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3323.