Radiation from frequent whole-body CT scans induces systemic immunosuppression and immune activation of tumor tissue.

OBJECTIVE

This study aims to elucidate the impact of repeated whole-body computed tomography (CT) scans on systemic immunity, the tumor immune microenvironment, and tumor control. This inquiry was prompted by clinical observations indicating a decrease in the levels of IFN-β and IFN-γ in patients' blood following whole-body CT scans.

METHODS

A Lewis lung carcinoma (LLC) mouse model was established and divided into two groups: a control group and a group subjected to multiple whole-body CT scanning radiation (WBCTSs). The study monitored tumor growth trends across both groups and employed a comprehensive set of analytical techniques-including enzyme-linked immunosorbent assay (ELISA), flow cytometry analysis, immunohistochemistry, RNA sequencing, and single-cell sequencing-to assess differences in cytokine profiles (IFN-β and IFN-γ), proportions of key immune cells, and gene expression variations between the groups.

RESULTS

Repeated CT scan radiation does not promote tumor progression. In tumor tissues subjected to multiple CT scans, an increase in the proportion of CD8+ T cells, elevated interferon levels, and up-regulation of genes associated with killing in CD8+ T cells and genes associated with Ifnb in macrophages were observed. In contrast, radiation from multiple whole-body CT scans resulted in a decrease in the proportion of CD8+ T cells in the blood and spleen, a decrease in serum interferon levels, and down-regulation of killing-related genes in CD8+ T cells.

CONCLUSION

Our results suggest that repeated whole-body CT scanning radiation induces systemic immunosuppression and immune activation in tumor tissues. Multiple repeated CT scans do not promote tumor progression.