T lineage commitment occurs in a discrete, stage-specific manner during thymic ontogeny. Intrathymic precursor transfer experiments and the identification of CD4(+)8+ double-positive (DP), V alpha 14J alpha 18 natural T (iNKT) cells suggest that commitment to this lineage might occur at the DP stage. Nevertheless, this matter remains contentious because others failed to detect V alpha 14J alpha 18-positive iNKT cells that are CD4(+)8+. In resolution to this issue, we demonstrate that retinoic acid receptor-related orphan receptor gamma (ROR gamma)0/0 thymi, which accumulate immature single-positive (ISP) thymocytes that precede the DP stage, do not rearrange V alpha 14-to-J alpha 18 gene segments, suggesting that this event occurs at a post-ISP stage. Mixed radiation bone marrow chimeras revealed that RORgamma functions in an iNKT cell lineage-specific manner. Further, introgression of a Bcl-x(L) transgene into ROR gamma(0/0) mice, which promotes survival and permits secondary rearrangements of distal V alpha and J alpha gene segments at the DP stage, rescues V alpha 14-to-J alpha 18 recombination. Similarly, introgression of a rearranged V alpha 14J alpha 18 transgene into ROR gamma(0/0) mice results in functional iNKT cells. Thus, our data support the "T cell receptor-instructive (mainstream precursor) model" of iNKT cell lineage specification where V alpha 14-to-J alpha 18 rearrangement, positive selection, and iNKT cell lineage commitment occur at or after the DP stage of ontogeny.
Proc natl acad sci u s a
5114 - 5119
Animals, Base Sequence, CD4-Positive T-Lymphocytes, CD8-Positive T-Lymphocytes, Cell Differentiation, DNA, Complementary, Gene Rearrangement, T-Lymphocyte, Immunity, Innate, Killer Cells, Natural, Lymphopoiesis, Mice, Mice, Inbred C57BL, Mice, Knockout, Mice, Transgenic, Models, Immunological, Nuclear Receptor Subfamily 1, Group F, Member 3, Radiation Chimera, Receptors, Retinoic Acid, Receptors, Thyroid Hormone, T-Lymphocyte Subsets