Activation of human Valpha24NKT cells by alpha-glycosylceramide in a CD1d-restricted and Valpha24TCR-mediated manner.

Vact14NK(natural killer) T cells play an important role in controlling tumors or in preventing autoimmunity in the murine system. Valpha24NKT cells, the human counterpart of Valpha14NKT cells, may contribute to controlling the progression of autoimmune diseases in humans. These findings show the possibility that ligand(s) for these NKT cells can control the above-mentioned pathological conditions. Specific glycolipids such as alpha-galactosylceramide (alpha-GalCer) and alpha-glucosylceramide (alpha-GlcCer) have been identified as ligand(s) recognized by murine Valpha14NKT cells in a CD1d-restricted manner, but it remains unclear whether these glycolipids are ligand(s) for Valpha24NKT cells in humans. To determine whether alpha-glycosylceramide is presented by CD1d molecules in humans, we initially established a Valpha24NKT cell line specific for alpha-glycosylceramide using dendritic cell (DC) like cells from normal peripheral blood mononuclear cells (PBMC) in an autologous mixed leukocyte reaction (auto-MLR) system, and characterized the Valpha24NKT cell line. The Valpha24NKT cells were CD3+ CD4-CD8-Valpha24+Vbeta11+NKRP1A+ and specifically proliferated in response to alpha-glycosylceramide in CD1d-restricted and Valpha24TCR-mediated manner. The phenotypic and functional similarities between murine Valpha14NKT cells and human Valpha24NKT cells suggest that Valpha24NKT cells may play an important role in controlling tumors or in preventing autoimmunity as observed with Valpha14NKT cells.