Ionizing radiation inhibition of distant untreated tumors (abscopal effect) is immune mediated

摘要: Abstract Purpose Ionizing radiation can reduce tumor growth outside the field of radiation, known as abscopal effect. Although it has been reported in multiple malignancies, effect remains a rare and poorly understood event. generates inflammatory signals and, principle, could provide both tumor-specific antigens from dying cells maturation stimuli that are necessary for dendritic cells' activation T cells. We therefore tested hypothesis elicited by is immune mediated. This was directly enhancing number available using factor Flt3-Ligand (Flt3-L). Methods materials Mice bearing syngeneic mammary carcinoma, 67NR, flanks were treated with Flt3-L daily 10 days after local therapy (RT) to only 1 2 tumors at single dose or 6 Gy. The second nonirradiated used indicator Data analyzed repeated measures regression. Results RT alone led delay exclusively irradiated 67NR tumor, expected. Surprisingly, also impaired combination Flt3-L. As control, had no without RT. Importantly, shown be specific, because A20 lymphoma same mice containing not affected. Moreover, observed when cell deficient (nude) plus Conclusions These results demonstrate part mediated required mediate distant inhibition induced radiation.