Background: Cytokines are important for signaling between cells and tissues and constitute a humoral component of the response of cells and tissues to radiotherapy. Although several cytokines have been implicated in mediating radiation-induced reactions of normal tissues, the mechanisms are only beginning to be elucidated.
Methods: Published data on radiation-induced cytokine expression from cell culture, experimental and clinical studies are reviewed. Current models of cytokine-mediated multicellular interactions in radiation-induced reactions of the lung, skin and intestinal mucosa are presented.
Results and conclusion: The major cytokines in the radiation response of non-hemopoietic tissues include IL-6, IL-1, INF alpha and TGF beta. Different cell types interact via cytokines in a complex network of effector and receptor cells, including inflammatory cells, tissue-specific functional cells and fibroblasts. TGF beta appears to be of particular importance in the development of late reactions such as fibrosis.