[M2 macrophages inhibit CD8⁺ T cells and facilitate the malignant biological behavior of esophageal cancer cells].

Objective To explore the impact of M2 macrophages on the malignant biological behavior of esophageal cancer by inhibiting the anti-tumor ability of CD8⁺ T cells. Methods Using phorbol myristate acetate (PMA) combined with interleukin 4 (IL-4)/IL-13, we induced human monocytic leukemia cells (THP-1) to become M2 macrophages and the detected related inflammatory factors by real-time quantitative PCR. We used magnetic bead sorting to isolate CD8⁺ T cells from healthy volunteers' peripheral blood, and verified the purity of the sorted cells by flow cytometry. We established a non-contact co-culture system between CD8⁺ T cells and esophageal squamous carcinoma cells (CD8⁺ T cell), and established a non-contact co-culture system between M2 macrophages, CD8⁺ T cells, and esophageal squamous carcinoma cells (M2 macrophages combined with CD8⁺ T cell). The plate clone formation assay and CCK-8 cell toxicity assay were used to detect the proliferation ability of tumor cells in each group. The Transwell^TM assay was used to detect the invasive and migratory abilities of tumor cells in each group. Flow cytometry was used to detect and analyze the apoptosis of tumor cells in each group. GraphPadPrism9.5 software was used for statistical analysis and graphing. Results After induction, the expression of IL-10 and arginase 1 (Arg1) in macrophages was upregulated, while the expression of IL-12 and tumor necrosis factor-alpha (TNF-α) was downregulated, showing the characteristics of M2 macrophages. Peripheral blood CD8⁺ T cells were successfully selected by magnetic bead sorting, with a positive rate of over 90%. The proliferation, invasion, migration and anti-apoptosis ability of esophageal squamous carcinoma cells co-cultured with CD8⁺ T cells in the non-contact manner were significantly lower than those of the single cancer cell group; while the proliferation, invasion, migration and the anti-apoptosis ability of esophageal squamous carcinoma cells co-cultured with CD8⁺ T cells pretreated with M2 macrophage conditioned medium were significantly enhanced compared with those of esophageal squamous carcinoma and CD8⁺ T cells co-cultured group. Conclusion M2 macrophages promote the proliferation, invasion, migration, and anti-apoptosis of esophageal cancer cells by inhibiting the anti-tumor ability of CD8⁺ T cells.