Role of the Complementarity-Determining Region 3 (CDR3) of the TCR-β Chains Associated with the Vα14 Semi-Invariant TCR α-Chain in the Selection of CD4+ NK T Cells

Abstract

The NK1.1+TCRαβint CD4+, or double negative T cells (NK T cells) consist of a mixture of CD1d-restricted and CD1d-unrestricted cells. The relationships between CD4+NK1.1+ T cells and conventional T cells are not understood. To compare their respective TCR repertoires, NK1.1+TCRαβint, CD4+ T cells have been sorted out of the thymus, liver, spleen, and bone marrow of C57BL/6 mice. Molecular analysis showed that thymus and liver used predominantly the Vα14-Jα281 and Vβ 2, 7, and 8 segments. These cells are CD1d restricted and obey the original definition of NK T cells. The complementarity-determining region 3 (CDR3) sequences of the TCR Vβ8.2-Jβ2.5 chain of liver and thymus CD4+ NK T cells were determined and compared with those of the same rearrangements of conventional CD4+ T cells. No amino acid sequence or usage characteristic of NK T cells could be evidenced: the Vβ8.2-Jβ2.5 diversity regions being primarily the same in NK T and in T cells. No clonal expansion of the β-chains was observed in thymus and liver CD1d-restricted CD4+NK T cells, suggesting the absence of acute or chronic Ag-driven stimulation. Molecular analysis of the TCR used by Vα14-Jα281 transgenic mice on a Cα−/− background showed that the α-chain can associate with β-chains using any Vβ segment, except in NK T cells in which it paired predominately with Vβ 2, 7, and 8+ β-chains. The structure of the TCR of NK T cells thus reflects the affinity for the CD1d molecule rather than a structural constraint leading to the association of the invariant α-chain with a distinctive subset of Vβ segment.

Natural killer T cells reactive to a single glycolipid exhibit a highly diverse T cell receptor β repertoire and small clone size

“…Therefore, it remains possible that ␣-GalCer-reactive NK T cells in humans represent relatively few clones that have undergone significant expansion. On the other hand, the results here are in agreement with those from recent TcR sequence analyses (48,49). In these reports, however, either DN or CD4 ϩ cells selected for NK1.1 ϩ and TcR␤ expression were analyzed.…”

IL-15 availability conditions homeostasis of peripheral natural killer T cells

“…Mice transgenic for a functionally rearranged V␣14-J␣18 invariant TCR␣ chain on a TCR C␣ Ϫ/Ϫ background (V␣14Tg) have been extensively characterized (22,33,35,36). These mice show an increase in the frequency of NK1.1 ϩ T cells in the spleen, lymph nodes, and liver (refs.…”

Natural Killer T Cells Restricted by the Monomorphic MHC Class 1b CD1d1 Molecules Behave Like Inflammatory Cells

“…Ϫ/Ϫ mice (15) were obtained from The Jackson Laboratory (Bar Harbor, ME), and V␣14tg mice on the C␣ Ϫ/Ϫ background were previously described (7,16). All genetically modified mice were backcrossed to the C57BL/6 background at least six times, and animals were used between 6 and 12 wk of age.…”

“…Thus far, however, the CD1d molecules, do not have a known physiological ligand, although they bind glycolipids (2) in their highly hydrophobic groove and only the CD1d1 protein can properly fold in C57BL/6 mice (3); the murine structural equivalents of CD1a, -b, and -c have not been detected yet (3). In addition to some other T cell populations (4), CD1d molecules restrict populations of T cells with a distinctive TCR using a semi-invariant V␣14-J␣281 TCR ␣-chain predominantly associated with TCR V␤2, -7, and -8 ␤-chains in mice (5)(6)(7)(8) and V␣24-J␣Q/V␤ 11 in humans (9). Most of these cells also express NK markers, such as NK1.1 in C57BL/6 mice (8).…”