An invariant T cell receptor alpha chain is used by a unique subset of major histocompatibility complex class I-specific CD4+ and CD4-8- T cells in mice and humans.
The mouse thymus contains a mature T cell subset that is distinguishable from the mainstream thymocytes by several characteristics. It is restricted in its usage of T cell receptor (TCR) V beta genes to V beta 8, V beta 7, and V beta 2. Its surface phenotype is that of activated/memory cells. It carries the natural killer NK1.1 surface marker. Furthermore, though it consists entirely of CD4+ and CD4-8- cells, its selection in the thymus depends solely upon major histocompatibility complex (MHC) class I expression by cells of hematopoietic origin. Forced persistence of CD8, in fact, imparts negative selection. Here, we have studied the TCR repertoire of this subset and found that, whereas the beta chain V-D-J junctions are quite variable, a single invariant alpha chain V alpha 14-J281 is used by a majority of the TCRs. This surprisingly restricted usage of the V alpha 14-J281 alpha chain is dependent on MHC class I expression, but independent of the MHC haplotype. In humans, a similar unusual population including CD4-8- cells can also be found that uses a strikingly homologous, invariant alpha chain V alpha 24-JQ. Thus, this unique V alpha-J alpha combination has been conserved in both species, conferring specificity to some shared nonpolymorphic MHC class I/peptide self-ligand(s). This implies that the T cell subset that it defines has a specialized and important role, perhaps related to its unique ability to secrete a large set of lymphokines including interleukin 4, upon primary stimulation in vitro and in vivo.
Lantz
O
O
Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Bendelac
A
A
D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000032:analysis; D000950:Antigens, Ly; D000954:Antigens, Surface; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D016827:CD8 Antigens / Q000032:analysis*; D002352:Carrier Proteins / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000502:physiology; D015395:Histocompatibility Antigens Class I / Q000502:physiology*; D006801:Humans; D018960:Hyaluronan Receptors; D037181:Lectins, C-Type; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011506:Proteins / Q000032:analysis; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D011956:Receptors, Cell Surface / Q000032:analysis; D016201:Receptors, Lymphocyte Homing / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000502:physiology
D000941:Antigens; D000950:Antigens, Ly; D000954:Antigens, Surface; D016827:CD8 Antigens; D002352:Carrier Proteins; D015395:Histocompatibility Antigens Class I; D018960:Hyaluronan Receptors; C527203:KLRB1 protein, human; C527211:Klrb1c protein, mouse; D037181:Lectins, C-Type; D008024:Ligands; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011506:Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011956:Receptors, Cell Surface; D016201:Receptors, Lymphocyte Homing