IL6 and hemophagocytic syndrome: Numerous cytokines and chemokines linked to HLH in patients with CAR HLH, including IFN-γ, IL-6, IL-1β, IL-18, IL-18 binding protein (IL18bp), IL-8, MIP-1α, CXCL 9, and CXCL 10, were consistently and significantly elevated in comparison to patients without CAR HLH.