High parameter immune cell quantification in a melanoma-derived tumor model by Chipcytometry

Abstract

Immune evasion is a hallmark of cancer and the presence and interaction of immune cells within a tumor and its microenvironment can have a great impact on disease progression and prognosis. Unravelling the complex interplay of neoplastic and immune cells requires both phenotypic and spatial analysis of each involved cell population in the tissue. The aim of this study is to compare 3 methods of biomarker analysis in tissues, flow cytometry, immunohistochemistry (IHC) and Chipcytometry, in their ability to detect immune cells in a tumor model. NOD-Scid tg HLA-A2.1 mice were implanted with human Ma-Mel-19 melanoma cells. After 21 days, the mice were injected with human PBMC at the tumor site. Local treatment with Tasquinimod was performed three times once a week. Tumors, including the neighbouring PBMC injection site were excised on day 48 and immune cell content was analysed by Chipcytometry, flow cytometry and IHC. All three methods were successful in detecting human immune cells in the samples consisting mostly of T-cells (CD45+CD3+). However, flow cytometry and IHC were unable to provide either accurate localization or phenotyping data, respectively. With Chipcytometry we were able to specifically quantify tumor-infiltrating immune cells. In treated samples immune cell count (110/mm^2) and composition (72% T-cells) was significantly higher than in the untreated samples (54/mm^2, 49% T-cells). We show that Chipcytometry is able to produce “flow-like” quantitative data, while also retaining spatial information. This makes Chipcytometry a powerful tool for the study of immunological processes in tumors.