The role of peripheral inflammatory cells in predicting radiation pneumonitis

Background: Radiation pneumonitis (RP) is a common complication of thoracic radiation which affects patients’ ability to breathe, limits the deliverable intensity of radiotherapy and impairs clinical outcomes, indicating the need for timely diagnosis and management. The purpose of this study was to determine the predictive capability of two peripheral inflammatory cells for RP. Materials and Methods: A murine RP model was established using SD rats that received a single dose of 20 Gy thoracic radiation. At 2 and 4 weeks post-radiation, mice were processed to harvest lungs for hematoxylin -eosin (HE) staining and collect blood for flow cytometry analysis. Results: By 2 weeks post-radiation, histopathological changes had occurred in the lungs indicating the onset of RP. Peripheral CD45+HIS48+ granulocytes were significantly increased by the radiation treatment at both the early and later time points (P<0.05). However, we did not observe a statistically significant increase of CD45+CD11b/c+HIS48- monocytes/macrophages. Conclusion: Our study highlights the possibility that increased levels of peripheral CD45+HIS48+ granulocytes could serve as a predictive indicator of RP. Early detection provides the opportunity for early intervention and therefore, a reduction in the rate and extent of RP.