title: Natural killer cells as biomarkers of hyperbaric stress during a dry heliox saturation dive.
abstract: BACKGROUND
  Diving, hyperbaric oxygen, and decompression have been described as inducers of alterations in various components of the human immune system, such as the distribution of circulating lymphocytes. Hypothetically, the monitoring of specific lymphocyte subsets during hyperbaric exposure, including T- and NK-cell subsets, can serve as biomarkers of hyperbaric stress.
  
  
  METHODS
  Eight experienced saturation divers and eight reference subjects, naive to deep saturation diving, were examined. Peripheral blood mononuclear cells were isolated before and at different points during a 19.3-d dry heliox saturation dive to 2.64 MPa (254 msw). The NK cell cytotoxicity was estimated in a 4-h 51Cr-release assay using the NK cell sensitive tumor cell-line K562 as target cells. The major lymphocyte subpopulations, with special emphasis on the NK cell subsets, were phenotypically delineated by the use of 4-color flow cytometry.
  
  
  RESULTS
  Although NK cell cytotoxicity increased significantly in the divers during the compression phase and the reference subjects who remained in normoxic conditions outside the chamber, the NK cell cytotoxicity was significantly higher in the divers.
  
  
  CONCLUSIONS
  This finding, together with augmentation in the absolute number of circulating NK cells in the divers due to a possible activation of specific parts of the innate cellular immune system during hyperbaric exposure, suggests the monitoring of specific immune functions can be useful as biomarkers of hyperbaric-induced inflammatory stress.
authors.affiliation: Department of Anesthesiology and Intensive Care, Randers Regionshospital, Randers, Denmark. Jan.Krog@ki.au.dk
authors.forename: Jan
authors.initials: J
authors.lastname: Krog
authors.forename: Else K
authors.initials: EK
authors.lastname: Tønnesen
authors.forename: Claus F
authors.initials: CF
authors.lastname: Jepsen
authors.forename: Erik
authors.initials: E
authors.lastname: Parner
authors.forename: Kåre
authors.initials: K
authors.lastname: Segadal
authors.forename: Arvid
authors.initials: A
authors.lastname: Hope
authors.forename: Rune J
authors.initials: RJ
authors.lastname: Ulvik
authors.forename: Marianne E
authors.initials: ME
authors.lastname: Hokland
mesh_terms: D000328:Adult; D001469:Barotrauma / Q000276:immunology*; D015415:Biomarkers; D004242:Diving / Q000009:adverse effects*; D005434:Flow Cytometry; D006371:Helium; D006801:Humans; D007694:Killer Cells, Natural / Q000378:metabolism*; D016014:Linear Models; D016131:Lymphocyte Subsets / Q000378:metabolism*; D008297:Male; D015999:Multivariate Analysis; D010100:Oxygen
chemical_list: D015415:Biomarkers; D006371:Helium; C038949:heliox; D010100:Oxygen