<p>Radiotherapy serves as a crucial therapeutic modality for esophageal squamous cell carcinoma (ESCC). Beyond its role in tumor growth control, radiotherapy also exerts immunomodulatory effects on tumors and their microenvironment. This study investigates the potential impact of radiation on human leukocyte antigen class I (HLA-I) and the underlying mechanisms of tumor immunity. Changes in peripheral blood β2-microglobulin (β2M) levels were assessed pre- and post-radiotherapy. ESCC cells were subjected to radiation, and the expression of HLA-I was evaluated using reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. Differential gene expression analysis was conducted utilizing The Cancer Genome Atlas (TCGA) and transcriptome sequencing to explore the molecular mechanisms by which radiation may influence HLA-I expression. Interferon-gamma (IFN-γ) was identified as a central regulator of HLA-I expression by STRING database. ESCC cell lines were co-cultured with immune cells, following radiation exposure, the levels of secreted IFN-γ in the culture medium were quantified. Changes in T cells and dendritic cells (DCs) were detected via immunofluorescence. The study found that elevated β2M expression in peripheral blood cells of patients with ESCC was significantly associated with improved Disease-Free Survival (DFS). Radiation treatment was observed to enhance the expression of HLA-I in ESCC cells. Analysis of TCGA data and gene transcriptome sequencing identified the cytokine-cytokine receptor interaction as the most enriched pathway. IFN-γ was identified as the central cytokine in regulating HLA-I expression, with the capability to induce its expression. When ESCC cells were co-cultured with immune cells and treated with radiation, there was an increase in IFN-γ concentration in the medium, accompanied by altered distributions of DCs and T cells. These findings suggest that radiation may influence immune cells through the modulation of IFN-γ.</p>