Repeated exposure of human fibroblasts to ionizing radiation reveals an adaptive response that is not mediated by interleukin-6 or TGF-β

► Priming with ionizing radiation induced an adaptive response in human fibroblasts. ► Primed fibroblasts have an altered γH2AX spot size distributions and repair kinetics. ► Priming significantly altered cytokine secretion in the cell culture medium. ► IL6 nor TGF-β primed cells could mimic the IR-induced adaptive response.