Because NK cell cytotoxicity is mediated by releasing perforin and granulocytase rather than cytokines such as IL-1, IL-2, IL-6, TNF-α, IL-8, IL-10, and IL-15 released by CAR-T cells, or expressing the apoptosis-inducing ligands including Fas Ligand (FasL) and (TNF)-related apoptosis-inducing ligand (TRAIL), they rarely cause CRS and neurotoxicity (125). This evidence concerns the gene FASLG and congenital rubella syndrome.