Potential of targeting natural killer T cells for the treatment of autoimmune diseases

Natural killer (NK) T cells emerge as unique lymphocytes subsets implicated in the regulation of autoimmunity. Abnormalities in the numbers and functions of NKT cells have been observed in patients with diverse autoimmune diseases as well as in a variety of mouse strains that are genetically predisposed for the development of autoimmune diseases. Unlike conventional T cells that recognize peptides in association with major histocompatibility complex (MHC), NKT cells recognize glycolipid antigens presented by the nonpolymorphic MHC class I-like protein, CD1d. Recently, vigorous activation of NKT cells by synthetic glycolipids such as α-galactosylceramide (α-GC) or its sphingosine truncated derivative OCH have been shown to suppress autoimmune diseases such as experimental auto-immune encephalomyelitis (EAE), diabetes in nonobese diabetic (NOD) mice, and collagen-induced arthritis (CIA) by inducing T helper (Th) 2 bias of autoimmune T cells. In this review, we examine the potential roles of NKT cells in the pathogenesis of autoimmune disease regulation, and the recent advances in glycolipid therapy for autoimmune disease models. In addition, we summarize studies suggesting a role for NKT cells in human autoimmune disease, and discuss the potential of targeting NKT cells for the treatment of autoimmunity.