The upregulation of the cytokine IL-1β in exposed individuals with higher PCB plasma levels warrants further investigation in order to examine its role in the pathophysiology of autoimmune disorders and tumor promotion.
Finally, the inflammatory cytokines tumor necrosis factor-alpha and interleukin-1 beta, which are involved in tumor promotion and development, were found to act synergistically to up-regulate GDNF expression in both fibroblasts and tumor cells.