IL6 and neoplasm: Interleukins (ILs), a class of signaling proteins produced by immune cells, transmit signals between cells and mediate multiple immune effects.479 Several interleukin family members activate JAK/STAT signaling to regulate immune responses,452 with IL-6 thought to be involved in tumor immunity.480 IL-6 is highly expressed in the tumor microenvironment and is a major mediator of inflammation.