title: Natural killer cell receptor T-lymphocytes in normal and Helicobacter pylori-infected human gastric mucosa.
abstract: BACKGROUND
  Helicobacter pylori infection is associated with development of chronic inflammation and infiltration of immune cells into the gastric mucosa. As unconventional T-lymphocytes expressing natural killer cell receptors are considered to play central roles in the immune response against infection, a study investigating their frequencies in normal and H. pylori-infected gastric mucosa was undertaken.
  
  
  METHODS
  Flow cytometry was used to quantify T-cells expressing the natural killer cell markers CD161, CD56, and CD94 in freshly isolated lymphocytes from the epithelial and lamina propria layers of gastric mucosa. Thirteen H. pylori-positive and 24 H. pylori-negative individuals were studied.
  
  
  RESULTS
  CD94(+) T-cells were the most abundant (up to 40%) natural killer receptor-positive T-cell population in epithelial and lamina propria layers of H. pylori-negative gastric mucosa. CD161(+) T-cells accounted for about one-third of all T-cells in both compartments, but the lowest proportion were of CD56(+) T-cells. Compared with H. pylori-negative mucosa, in H. pylori-infected mucosa the numbers of CD161(+) T-cells were significantly greater (p = .04) in the epithelium, whereas the numbers of CD56(+) T-cells were lower (p = .01) in the lamina propria. A minor population (< 2%) of T-cells in both mucosal layers of H. pylori-negative subjects were natural killer T-cells, and whose proportions were not significantly different (p > .05) to those in H. pylori-infected individuals.
  
  
  CONCLUSIONS
  The predominance, heterogeneity, and distribution of natural killer cell receptor-positive T-cells at different locations within the gastric mucosa reflects a potential functional role during H. pylori infection and warrants further investigation.
authors.affiliation: Department of Biochemistry, School of Natural Sciences, National University of Ireland Galway, Ireland. joan.okeeffe@nuigalway.ie
authors.forename: Joan
authors.initials: J
authors.lastname: O'Keeffe
authors.forename: Carol M
authors.initials: CM
authors.lastname: Gately
authors.forename: Yvonne
authors.initials: Y
authors.lastname: O'Donoghue
authors.forename: Syed A
authors.initials: SA
authors.lastname: Zulquernain
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Stevens
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Moran
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019002:CD56 Antigen / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D005753:Gastric Mucosa / Q000276:immunology*; D016481:Helicobacter Infections / Q000276:immunology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055651:NK Cell Lectin-Like Receptor Subfamily B / Q000032:analysis; D051920:NK Cell Lectin-Like Receptor Subfamily D / Q000032:analysis; D055607:Receptors, Natural Killer Cell / Q000096:biosynthesis*; D016176:T-Lymphocyte Subsets / Q000737:chemistry* / Q000276:immunology*
chemical_list: D019002:CD56 Antigen; D055651:NK Cell Lectin-Like Receptor Subfamily B; D051920:NK Cell Lectin-Like Receptor Subfamily D; D055607:Receptors, Natural Killer Cell