TNF and neoplasm: Furthermore, part of the high PSA response observed in our series may be due to the abscopal effect, attributed to irradiation-induced immune mechanisms such as exposure to tumor antigen, increased maturation of antigen-presenting cells taking up antigen released by dying cells, and production of interleukin-6 and tumor necrosis factor-α, as well as changes in the tumor microenvironment for improved recruitment of effector T cells (31).