Cd1d-specific NK1.1⁺ T cells with a transgenic variant TCR

The majority of T lymphocytes carrying the NK cell marker NK1.1 (NKT cells) depend on the CD1d molecule for their development and are distinguished by their potent capacity to rapidly secrete cytokines upon activation. A substantial fraction of NKT cells express a restricted TCR repertiore using an invariant TCR Vα14-Jα281 rearrangement and a limited set of TCR Vβ segments, implying recognition of a limited set of CD1d- associated ligands. A second group of CD1d-reactive T cells use diverse TCR potentially recognizing a larger diversity of ligands presented on CD1d. In TCR-transgenic mice carrying rearranged TCR genes from a CD1d-reactive T cell with the diverse type receptor (using Vα3.2/Vβ9 rearrangements), the majority of T cells expressing the transgenic TCR had the typical phenotype of NKT cells. They expressed NK1.1, CD122, intermediate TCR levels, and markers indicating previous activation and were CD4/CD8 double negative or CD4⁺. Upon activation in vitro, the cells secreted large amounts of IL-4 and IFN-γ, a characteristic of NKT cells. In mice lacking CD1d, TCR-transgenic cells with the NKT phenotype were absent. This demonstrates that a CD1d- reactive TCR of the 'non-Vα 14' diverse type can, in a ligand-dependent way, direct development of NK1.1⁺ T cells expressing expected functional and cell-surface phenotype characteristics.