Li transplanted NKT cells lacking IFN-γ, IL-4, IL-21, perforin or granzyme B into NKT cell-deficient apoE -/- Jα18 -/- mice and found that only the mice lacking perforin and granzyme B showed a reduction in atherosclerosis, which demonstrates that CD4+NKT cells promote atherosclerosis mainly by expressing perforin and granzyme [85]. The gene discussed is IL21; the disease is atherosclerosis.