IL6 and hand, foot and mouth disease: Previous studies had examined features of the expression of cytokines and chemokines in severe HFMD patients and found that interleukin 1β (IL-1β), IL-6, IL-10, chemokine (C-X-C motif) ligand 10 (CXCL10), and tumor necrosis factor (TNF) in peripheral fluids were significantly increased compared with their levels in mildly ill patients (10, 11).