title: The role of natural killer cells in the defense against Listeria monocytogenes lessons from a rat model.
abstract: Ly49 receptors in rodents, like killer cell immunoglobulin-like receptors in humans, regulate natural killer (NK) cell activity. Although inhibitory Ly49 receptors clearly recognize classical major histocompatibility complex class I (MHC-I) molecules, the role for the activating Ly49 receptors has been less well understood. Here, we discuss recent data from a rat model for listeriosis. Rats depleted of NK cells, or more specifically the Ly49 receptor-bearing cells, showed increased bacterial loads in their spleen. Athymic nude rats with no functional T cells but increased numbers of Ly49-expressing NK cells were more resistant to infection, indicating a central role of NK cells in early immune defense against Listeria in this species. Listeria infection of macrophages or enteric epithelial cells led to upregulation of MHC-I, including nonclassical (Ib) molecules not regularly recognized by T cells. We have shown that activating Ly49 receptors are more efficiently stimulated when binding to upregulated class Ib antigens on infected cells. From this we postulate that activating Ly49 receptors may have a sentinel function in the early immune response against Listeria in detecting diseased cells 'flagged' by increased MHC-Ib expression.
authors: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors: Christian
authors: C
authors: Naper
authors: Hamid
authors: H
authors: Shegarfi
authors: Marit
authors: M
authors: Inngjerdingen
authors: Bent
authors: B
authors: Rolstad
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate; D007694:Killer Cells, Natural / Q000276:immunology*; D008089:Listeria monocytogenes / Q000276:immunology* / Q000472:pathogenicity; D008088:Listeriosis / Q000276:immunology*; D008212:Lymphocyte Depletion; D055650:NK Cell Lectin-Like Receptor Subfamily A / Q000276:immunology*; D051381:Rats
chemical_list: D015395:Histocompatibility Antigens Class I; D055650:NK Cell Lectin-Like Receptor Subfamily A