title: Ultrastructure and cytochemical staining characteristics of canine natural killer cells.
abstract: BACKGROUND
  The purpose of this work was to describe the ultrastructure and cytochemical staining characteristics of canine peripheral blood lymphocytes with natural killer (NK) cell activity, with comparison made to non-NK lymphocytes.
  
  
  METHODS
  Canine lymphocyte populations evaluated for ultrastructure, cytochemical staining, and NK function (by 51chromium release assay) included: peripheral blood lymphocytes; lymphocytes from band 1 (NK-enriched), band 2, and the pellet of a 45/50% percoll gradient; lymphocytes from the supernatant fluid (non-conjugated lymphocytes) and pellet (lymphocytes conjugated to tumor cell targets) of a 17% percoll gradient; and null (CD4-CD8-) and CD4-CD8+ lymphocytes.
  
  
  RESULTS
  NK activity was concentrated in band 1 lymphocytes of the 45/50% percoll gradient with further enhancement of activity occurring in sorted null cells. Canine NK cells were 5.5 to 6.5 microns in diameter with a reniform (kidney bean shape) nucleus, and electron-dense cytoplasmic granules. NK cells (percoll band 1 cells and null cells) had larger cell and nuclear area, and less round nuclei when compared to non-NK lymphocytes. The overall cytochemical staining (chloracetate esterase, peroxidase, sudan black B, naphthyl acetate esterase, naphthyl butyrate esterase periodic acid-Schiff stain, and acid phosphatase with and without tartrate) pattern was similar in all the lymphocyte populations evaluated.
  
  
  CONCLUSIONS
  This work confirms the usefulness of a 45/50% percoll gradient in obtaining a NK-enriched fraction of canine lymphocytes, and shows further enhancement of NK activity in sorted CD4- CD8- cells. The ultrastructure of canine NK cells is similar to that reported for human NK cells, but is different from that of other canine peripheral blood lymphocytes. Standard cytochemical staining does not discriminate canine NK cells from other lymphocytes.
authors.affiliation: Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana 47907-1248, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Knapp
authors.forename: J J
authors.initials: JJ
authors.lastname: Turek
authors.forename: D B
authors.initials: DB
authors.lastname: DeNicola
authors.forename: T C
authors.initials: TC
authors.lastname: Chan
authors.forename: W O
authors.initials: WO
authors.lastname: Carter
authors.forename: P W
authors.initials: PW
authors.lastname: Snyder
authors.forename: J P
authors.initials: JP
authors.lastname: Robinson
mesh_terms: D000818:Animals; D004285:Dogs / Q000097:blood*; D007694:Killer Cells, Natural / Q000737:chemistry* / Q000648:ultrastructure*; D008214:Lymphocytes / Q000737:chemistry / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000662:veterinary; D013194:Staining and Labeling / Q000662:veterinary