<prompt> All of the following are pyrogenic cytokines, except:Interleukin 18 IL-18Interleukin 6 IL-6Tumor Necrosis Factor TNFInterferon a IFN a  <response>: Interleukin 18 is not a pyrogenic cytokine. IL-18, a member of the Il-1 family doesnot appear to be a pyrogenic cytokine- harrison. Pyrogenic Cytokines: Cytokines are small protein that regulate immune, inflammatory and hematopoietic processes Those cytokines that cause fever ;are called as pyrogenic cytokines formerly called Endogenous pyrogens The pyrogenic cytokines include IL-1, IL-6, TNF, CNTF and IFNa IL-18, a member of the IL-1 family doesnot appear to be a pyrogenic cytokine IL-1 and TNF appear to be the most potent pyrogenic cytokines and induce fever at low doses while higher dose is required to induce fever with IL-6. Other pyrogenic cytokines probably exist but the above constitute the major pyrogenic cytokines Pyrogenic Cytokines: Interleukin-I IL-1 Interleukin-6 IL-6 Tumor necrosis Factor TNF Interferon-a IFN- a Ref: Ananthanarayana 10th edition Pgno: 156 