title: Expansion and Protection by a Virus-Specific NK Cell Subset Lacking Expression of the Inhibitory NKR-P1B Receptor during Murine Cytomegalovirus Infection.
abstract: NK cells play a major role in immune defense against human and murine CMV (MCMV) infection. Although the MCMV genome encodes for MHC class I-homologous decoy ligands for inhibitory NK cell receptors to evade detection, some mouse strains have evolved activating receptors, such as Ly49H, to recognize these ligands and initiate an immune response. In this study, we demonstrate that approximately half of the Ly49H-expressing (Ly49H(+)) NK cells in the spleen and liver of C57BL/6 mice also express the inhibitory NKR-P1B receptor. During MCMV infection, the NKR-P1B(-)Ly49H(+) NK cell subset proliferates to constitute the bulk of the NK cell population. This NK cell subset also confers better protection against MCMV infection compared with the NKR-P1B(+)Ly49H(+) subset. The two populations are composed of cells that differ in their surface expression of receptors such as Ly49C/I and NKG2A/C/E, as well as developmental markers, CD27 and CD11b, and the high-affinity IL-2R (CD25) following infection. Although the NKR-P1B(+) NK cells can produce effector molecules such as IFNs and granzymes, their proliferation is inhibited during infection. A similar phenotype in MCMV-infected Clr-b-deficient mice, which lack the ligand for NKR-P1B, suggests the involvement of ligands other than the host Clr-b. Most interestingly, genetic deficiency of the NKR-P1B, but not Clr-b, results in accelerated virus clearance and recovery from MCMV infection. This study is particularly significant because the mouse NKR-P1B:Clr-b receptor:ligand system represents the closest homolog of the human NKR-P1A:LLT1 system and may have a direct relevance to human CMV infection.
authors: Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; munirrahimm@dal.ca james.carlyle@utoronto.ca.
authors: Mir Munir A
authors: MM
authors: Rahim
authors: Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada;
authors: Andrew
authors: A
authors: Wight
authors: Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; College of Applied Medical Sciences, Taibah University, 30001 Madinah Munawwarah, Saudi Arabia;
authors: Ahmad Bakur
authors: AB
authors: Mahmoud
authors: Department of Immunology, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario M4N 3M5, Canada; and.
authors: Oscar A
authors: OA
authors: Aguilar
authors: Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada;
authors: Seung-Hwan
authors: SH
authors: Lee
authors: Department of Human Genetics, McGill University, Montreal, Quebec H3G 0B1, Canada.
authors: Silvia M
authors: 0000-0002-4069-4276
authors: SM
authors: Vidal
authors: Department of Immunology, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario M4N 3M5, Canada; and munirrahimm@dal.ca james.carlyle@utoronto.ca.
authors: James R
authors: JR
authors: Carlyle
authors: Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada;
authors: Andrew P
authors: AP
authors: Makrigiannis
mesh_terms: D000818:Animals; D006566:Herpesviridae Infections / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D018146:Muromegalovirus / Q000276:immunology / Q000502:physiology; D055651:NK Cell Lectin-Like Receptor Subfamily B / Q000172:deficiency / Q000235:genetics / Q000276:immunology*
chemical_list: C527212:Klrb1b protein, mouse; D008024:Ligands; D055651:NK Cell Lectin-Like Receptor Subfamily B