title: Differential regulation of Ly49 expression on CD4+ and CD4-CD8- (double negative) NK1.1+ T cells.
abstract: The pan-NK cell marker NK1.1, present in some mouse strains, is also found on a subset of TCRalphabeta+ lymphocytes termed NKT cells. These cells are primarily CD4+ or CD4-CD8- (double negative, DN), and both NKT subpopulations contain cells reactive with the MHC class I-like molecule CD1d. Murine NK cells express clonally distributed inhibitory receptors of the Ly49 family that bind to different alleles of MHC class I molecules and transmit negative signals regulating NK cell function. Ly49 receptors are also found on TCRalphabeta+ NK1.1+ T cells. To investigate the potential role of inhibitory Ly49 markers in the regulation of NKT cells, we have done a thorough analysis of their expression on different NKT populations. The CD4+ and DN NK1.1+ T cell subsets have traditionally been dealt with as one NK1.1+ T cell population, but we found dramatic differences between these two NKT cell subsets. We demonstrate here expression of Ly49 receptors on DN, but not on CD4+, NK1.1+ T cells in spleen and liver. Absence of the specific MHC class I ligand in the host was associated with elevated levels of expression and, to a greater extent than has been found for NK cells, increased the frequencies of Ly49-positive cells within the DN subset, while CD4+ NK1.1+ cells remained negative. In the thymus and bone marrow both NK1.1+ T cell subsets contained high frequencies of Ly49-positive cells. Results from in vitro stimulation of DN NKT cells further suggest that activation and expansion of NKT cell subsets are regulated by the Ly49 receptors.
authors.affiliation: Department of Cell and Molecular Biology, Lund University, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Sköld
authors.forename: S
authors.initials: S
authors.lastname: Cardell
mesh_terms: D000818:Animals; D000941:Antigens / Q000032:analysis*; D000950:Antigens, Ly; D000954:Antigens, Surface; D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D008822:Mice, Transgenic; D055651:NK Cell Lectin-Like Receptor Subfamily B; D009928:Organ Specificity; D011506:Proteins / Q000032:analysis*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D055630:Receptors, NK Cell Lectin-Like; D016176:T-Lymphocyte Subsets / Q000378:metabolism*
chemical_list: D000941:Antigens; D000950:Antigens, Ly; D000954:Antigens, Surface; D015704:CD4 Antigens; D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I; C527211:Klrb1c protein, mouse; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011506:Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D055630:Receptors, NK Cell Lectin-Like