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Jason Ptacek, Robert W Johnson, Joann P Palma, Jay G Tarolli, Yari Sigal, Rachel Finck, Murat Aksoy, Yi Zhang, Jessica Finn, Immune profiling of the tumor microenvironment (TME) using multiplexed ion beam imaging (MIBI), The Journal of Immunology, Volume 204, Issue 1_Supplement, May 2020, Page 242.53, https://doi.org/10.4049/jimmunol.204.Supp.242.53
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Abstract
Understanding the cell types present in the tumor microenvironment and their activation state is at the forefront of immunotherapy research. To address this, MIBI has been developed to simultaneously image more than 40 markers at single cell resolution. Staining of 10 NSCLC formalin-fixed paraffin embedded tissue sections was performed with a panel of 20 metal labeled antibodies stained together. The tissue was imaged at subcellular resolution using an ion beam and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Masses of detected species were assigned to target biomolecules given the unique label of each antibody and multi-step processing and segmentation were performed to create images of the TME. Each tumor sample was imaged across 10 regions of interest (ROIs) to assess heterogeneity of the TME. The resulting single cell segmentation enabled quantitative analyses of both marker expression and the spatial relationships between cells of different types. At the highest level, cells were classified as immune (CD45) and tumor cells (keratin) based on measured intensities of marker expression. Co-expression of markers were used to classify B cells, macrophages, and T cells subsets. Markers associated with immune suppression such as PD-L1 were also quantified. Cell types and their frequency were compared within the 10 ROIs collected per sample as well as between samples. Finally, distances between tumor and the closest immune cell were measured as a means for describing the spatial organization of the TME, which has been linked to patient survival. In conclusion, MIBI offers high-parameter capability, at a sensitivity and resolution uniquely suited to understanding the complex tumor immune landscape.
