Natural killer T cells (NKT cells) are a unique subset of the mature T lymphocytes, and can recognize glycolipids presented by CDld molecules expressed on antigen-presenting cells through cell recognition pathway. After activation, NKT cells can secrete large mounts of cytokines which involve in innate immune and acquired immune response. NKT cells can also act as direct effector cells via cytolysis or granulysin. Studies have shown that NKT cells play an important role in anti-intracellular bacterial infection.