Hepatic Artery Embolization Reduces Tumor-infiltrating-CD8-positive Lymphocytes in an Orthotopic Rat Hepatocellular...

Hepatic artery embolization is a locoregional treatment for hepatocellular carcinoma that may modulate the tumor immune microenvironment. However, its effects on tumor-infiltrating cluster of differentiation 8-positive lymphocytes remain unclear. This study evaluates changes in tumor-infiltrating cluster of differentiation 8-positive lymphocytes following hepatic artery embolization in an orthotopic rat hepatocellular carcinoma model using flow cytometry and immunohistochemistry.

Orthotopic hepatocellular carcinoma was established in rats using N1S1 cells. Animals were divided into an hepatic artery embolization group (n = 11) and a control group (n = 11). One week after the procedures, liver tumor tissues were harvested, and flow cytometry and immunohistochemistry were performed to quantify total and exhausted cluster of differentiation 8-positive lymphocytes.

Tumor-infiltrating cluster of differentiation 8-positive lymphocytes significantly decreased in the hepatic artery embolization group compared to controls by both flow cytometry (0.13 ± 0.09 vs. 0.46 ± 0.27 × 10⁶/g, p < 0.01) and immunohistochemistry (14.67 ± 15.17 vs. 31.56 ± 20.98 cells/field of view, p < 0.05). However, the proportion of exhausted cluster of differentiation 8-positive lymphocytes by flow cytometry remained unchanged (8.24 ± 3.66% vs. 8.88 ± 2.60%, p = 0.72).

Hepatic artery embolization reduces the number of tumor-infiltrating cluster of differentiation 8-positive lymphocytes without altering the proportion of exhausted T cells. These findings suggest that, to increase hepatic artery embolization efficacy in combination with immunotherapy, a strategy of recruiting more cluster of differentiation 8-positive lymphocytes into the tumor tissue may be necessary.