title: External and internal calibration of the MHC class I-specific receptor Ly49A on murine natural killer cells.
abstract: Expression of the H-2Dd-specific inhibitory receptor Ly49A on murine NK cells is subject to MHC class I-dependent modulation in vivo. As a result, NK cells in H-2Dd-transgenic mice express low cell surface levels of Ly49A, whereas NK cells from nontransgenic C57BL/6 (B6) mice express high levels. The purpose of this study was to assess the role of MHC class I molecules on the NK cell itself vs those on surrounding cells in this calibration and to test whether the Ly49A levels are subject to regulation in mature NK cells also. Analysis of transgenic mice with mosaic expression of an H-2Dd/Ld transgene showed that MHC class I molecules on surrounding cells (external ligands) and on the NK cell itself (internal ligands) played distinct roles in the determination of Ly49A levels. External ligands were involved in down-regulation of Ly49A levels in vivo, whereas internal ligands kept the down-regulated levels of Ly49A low upon NK cell activation in vitro. Furthermore, in an experimental system based on adoptive transfer of spleen cells, receptor down-regulation of Ly49A occurred as a rapid adaptation process in mature NK cells after interaction with the H-2Dd ligand in vivo. This suggests that Ly49 levels are not fixed but can be changed in mature NK cells when they are exposed to a changed MHC class I environment.
authors.affiliation: Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Kåse
authors.forename: M H
authors.initials: MH
authors.lastname: Johansson
authors.forename: M Y
authors.initials: MY
authors.lastname: Olsson-Alheim
authors.forename: K
authors.initials: K
authors.lastname: Kärre
authors.forename: P
authors.initials: P
authors.lastname: Höglund
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000950:Antigens, Ly; D000954:Antigens, Surface / Q000378:metabolism; D002138:Calibration; D002352:Carrier Proteins / Q000378:metabolism*; D002450:Cell Communication / Q000276:immunology; D002478:Cells, Cultured; D018920:Coculture Techniques; D015536:Down-Regulation / Q000276:immunology; D006183:H-2 Antigens / Q000096:biosynthesis / Q000378:metabolism*; D007376:Interleukin-2 / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism* / Q000637:transplantation; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009030:Mosaicism / Q000276:immunology; D055650:NK Cell Lectin-Like Receptor Subfamily A; D011971:Receptors, Immunologic / Q000378:metabolism*; D055630:Receptors, NK Cell Lectin-Like
chemical_list: D000950:Antigens, Ly; D000954:Antigens, Surface; D002352:Carrier Proteins; D006183:H-2 Antigens; D007376:Interleukin-2; C527088:Klra1 protein, mouse; D037181:Lectins, C-Type; D008565:Membrane Proteins; D055650:NK Cell Lectin-Like Receptor Subfamily A; D011971:Receptors, Immunologic; D055630:Receptors, NK Cell Lectin-Like