Luteolin exerts anti-tumour immunity in hepatocellular carcinoma by accelerating CD8⁺ T lymphocyte infiltration

Luteolin, a commonly used traditional Chinese medicine, has been utilized for several decades in the treatment of hepatocellular carcinoma (HCC). Previous research has demonstrated its anti-tumour efficacy, but its underlying mechanism remains unclear. This study aimed to assess the therapeutic effects of luteolin in H22 tumour-bearing mice. luteolin effectively inhibited the growth of solid tumours in a well-established mouse model of HCC. High-throughput sequencing revealed that luteolin treatment could enhance T-cell activation, cell chemotaxis and cytokine production. In addition, luteolin helped sustain a high ratio of CD8⁺ T lymphocytes in the spleen, peripheral blood and tumour tissues. The effects of luteolin on the phenotypic and functional changes in tumour-infiltrating CD8⁺ T lymphocytes were also investigated. Luteolin restored the cytotoxicity of tumour-infiltrating CD8⁺ T lymphocytes in H22 tumour-bearing mice. The CD8⁺ T lymphocytes exhibited intensified phenotype activation and increased production of granzyme B, IFN-γ and TNF-α in serum. The combined administration of luteolin and the PD-1 inhibitor enhanced the anti-tumour effects in H22 tumour-bearing mice. Luteolin could exert an anti-tumour immune response by inducing CD8⁺ T lymphocyte infiltration and enhance the anti-tumour effects of the PD-1 inhibitor on H22 tumour-bearing mice.