Mechanisms of CAR-T-related HLH/MAS include (a) Lysis of tumor cells result in release of large quantities of inflammatory cytokines and pro-inflammatory cytokines (22, 117); (b) Induction of CD8+ T-cells by pro-inflammatory factors results in production of high amounts of Th1 cytokines, such as IFN-γ, TNF-α, and IL-6, which forms a positive feedback loop of inflammation (117); (c) Activated CAR-T cells can release numerous cytokines (23, 24); (d) IFN-γ is correlated with MAS, high levels of IFN-γ are correlated with severe MAS (118). This evidence concerns the gene IL6 and macrophage activation syndrome.