IL6 and hand, foot and mouth disease: Elevated serum levels of inflammatory cytokines, including IL-3, IL-6, IL-12p40, and TNF-α, and decreased levels of serum biomarkers, including IL-1Ra, IL-8, IL-16, soluble ICAM-1, CXCL-1, and CCL27, were found in HFMD cases, which suggests that systemic inflammation is involved in the etiology of HFMD.