Generation and characterisation of CD1d tetramer produced by a lentiviral expression system

The alpha-galactosylceramide (alphaGalCer)-loaded CD1d tetramer remains the most powerful tool in identifying natural killer T (NKT) cells, a subpopulation of T cells that express an unusual semi-invariant T cell antigen receptor, and mediate a variety of proinflammatory and immunoregulatory functions. The difficulty of generating large amounts of the alphaGalCer-CD1d tetramer has limited its availability and consequently hampered the study of NKT cells. In this report, we used a lentiviral system to generate stable cell lines producing beta2m-CD1d single chain protein in large quantities and in a relatively short period of time. When the protein was loaded with alphaGalCer and tetramerised with fluorescence-labelled streptavidin, its ability to efficiently bind to NKT cells was confirmed both by phenotype analysis and functional study. The CD1d tetramer generated from these stable cell lines should facilitate a wide range of studies on the biology and clinical applications of CD1d-restricted NKT cells.